Applying the Theory of Planned Behavior to Predict Dairy Product Consumption by Older Adults Article 2022
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ABSTRACT
Objective:The purpose of this study was to explain intention
to consume dairy products and consumption of dairy prod-
ucts by older adults using the Theory of Planned Behavior
(TPB). The factors examined were attitudes,subjective
norms, and perceived behavioral control.
Design: A cross-sectional questionnaire was administered.
Setting: Community centers with congregate dining pro-
grams, group classes, and recreational events for older adults.
Subjects: One hundred and sixty-two older adults (mean age
75 years) completed the questionnaire. Subjects were mostly
women (76%) and white (65%), with about half having less
than a high school education or completing high school.
Variables Measured:Variables based on the TPB were
assessed through questionnaire items that were constructed
to form scales measuring attitudes, subjective norms, per-
ceived behavioral control, and intention to consume dairy
products. Dairy product consumption was measured using a
food frequency questionnaire.
Analysis: Regression analyses were used to determine the
association between the scales for the 3 variables proposed in
the TPB and intention to consume and consumption of
dairy products; theα level was set at .05 to determine the
statistical significance of results.
Results: Attitudes toward eating dairy products and per-
ceived behavioral control contributed to the model for pre-
dicting intention, whereas subjective norms did not. Atti-
tudes toward eating dairy products were slightly more
important than perceived behavioral control in predicting
intention. In turn, intention was strongly related to d
product consumption, and perceived behavioral control
independently associated with dairy product consumptio
Conclusions and Implications:These results suggest t
ity of the TPB in explaining dairy product consumption fo
older adults. Nutrition education should focus on improv
attitudes and removing barriers to consumption of d
products for older adults.
KEY WORDS: dairy product consumption, older adults,
Theory of Planned Behavior, questionnaire research
(J Nutr Educ Behav. 2003;35:294-301.)
INTRODUCTION
Based on National Health and Nutrition Examination Sur
vey (NHANES) data (1988-1994), it was estimated that 1
of adults aged 50 years and older had osteoporosis
measured by low total femur bone mineral density
adjusted to the year 2000 standard population).1 A meta-
analysis regarding the effect of calcium on bone density
fractures in postmenopausal women found that calcium
more effective than placebo in reducing rates of bone lo
with a trend toward a reduction in vertebral fracture2
Adequate calcium intake may be a simple and inexpensi
strategy to prevent osteoporosis,which is a major public
health problem. A recent review of national dietary intak
data showed that calcium intake was about half of the re
ommended level for women in their 50s to 80s,whereas
intake for men was slightly higher but still less than reco
mended.3 Dairy foods contribute about 73% of the calcium
in the US per capita food supply.4 Based on 24-hour recall
data, intake of dairy products for adults 50 years and ov
reported to be 1.3 servings per day for women and 1.0 t
servings per day for men.5 Because of the positive health
benefits derived from an adequate intake of dairy produ
and therefore calcium, an increase in consumption of da
products by older adults is recommended.
294
R ESEARCH ART I C L E
Applying the Theory of Planned Behavior to Predict Dairy Produc
Consumption by Older Adults
K YUNGWON K IM , PH D; 1 M ARLA R E I C K S, PH D, RD; 2 SARA SJOBERG , BS2
1Department of Food Science and Nutrition, Seoul Women’s University, Seoul, Korea;2Department of Food Science
and Nutrition, University of Minnesota, St. Paul, Minnesota
Funding for this project was obtained from the Minnesota Agricultural Experiment
Station (MIN-054-026).
Address for correspondence: Marla Reicks, PhD, RD, Department of Food Science
and Nutrition, 1334 Eckles Avenue, St. Paul, MN 55108;Tel: (612) 624-4735; Fax: (612)
625-5272; E-mail: mreicks@umn.edu.
©2003 SOCIETY FOR NUTRITION EDUCATION
Objective:The purpose of this study was to explain intention
to consume dairy products and consumption of dairy prod-
ucts by older adults using the Theory of Planned Behavior
(TPB). The factors examined were attitudes,subjective
norms, and perceived behavioral control.
Design: A cross-sectional questionnaire was administered.
Setting: Community centers with congregate dining pro-
grams, group classes, and recreational events for older adults.
Subjects: One hundred and sixty-two older adults (mean age
75 years) completed the questionnaire. Subjects were mostly
women (76%) and white (65%), with about half having less
than a high school education or completing high school.
Variables Measured:Variables based on the TPB were
assessed through questionnaire items that were constructed
to form scales measuring attitudes, subjective norms, per-
ceived behavioral control, and intention to consume dairy
products. Dairy product consumption was measured using a
food frequency questionnaire.
Analysis: Regression analyses were used to determine the
association between the scales for the 3 variables proposed in
the TPB and intention to consume and consumption of
dairy products; theα level was set at .05 to determine the
statistical significance of results.
Results: Attitudes toward eating dairy products and per-
ceived behavioral control contributed to the model for pre-
dicting intention, whereas subjective norms did not. Atti-
tudes toward eating dairy products were slightly more
important than perceived behavioral control in predicting
intention. In turn, intention was strongly related to d
product consumption, and perceived behavioral control
independently associated with dairy product consumptio
Conclusions and Implications:These results suggest t
ity of the TPB in explaining dairy product consumption fo
older adults. Nutrition education should focus on improv
attitudes and removing barriers to consumption of d
products for older adults.
KEY WORDS: dairy product consumption, older adults,
Theory of Planned Behavior, questionnaire research
(J Nutr Educ Behav. 2003;35:294-301.)
INTRODUCTION
Based on National Health and Nutrition Examination Sur
vey (NHANES) data (1988-1994), it was estimated that 1
of adults aged 50 years and older had osteoporosis
measured by low total femur bone mineral density
adjusted to the year 2000 standard population).1 A meta-
analysis regarding the effect of calcium on bone density
fractures in postmenopausal women found that calcium
more effective than placebo in reducing rates of bone lo
with a trend toward a reduction in vertebral fracture2
Adequate calcium intake may be a simple and inexpensi
strategy to prevent osteoporosis,which is a major public
health problem. A recent review of national dietary intak
data showed that calcium intake was about half of the re
ommended level for women in their 50s to 80s,whereas
intake for men was slightly higher but still less than reco
mended.3 Dairy foods contribute about 73% of the calcium
in the US per capita food supply.4 Based on 24-hour recall
data, intake of dairy products for adults 50 years and ov
reported to be 1.3 servings per day for women and 1.0 t
servings per day for men.5 Because of the positive health
benefits derived from an adequate intake of dairy produ
and therefore calcium, an increase in consumption of da
products by older adults is recommended.
294
R ESEARCH ART I C L E
Applying the Theory of Planned Behavior to Predict Dairy Produc
Consumption by Older Adults
K YUNGWON K IM , PH D; 1 M ARLA R E I C K S, PH D, RD; 2 SARA SJOBERG , BS2
1Department of Food Science and Nutrition, Seoul Women’s University, Seoul, Korea;2Department of Food Science
and Nutrition, University of Minnesota, St. Paul, Minnesota
Funding for this project was obtained from the Minnesota Agricultural Experiment
Station (MIN-054-026).
Address for correspondence: Marla Reicks, PhD, RD, Department of Food Science
and Nutrition, 1334 Eckles Avenue, St. Paul, MN 55108;Tel: (612) 624-4735; Fax: (612)
625-5272; E-mail: mreicks@umn.edu.
©2003 SOCIETY FOR NUTRITION EDUCATION
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Journal of Nutrition Education and Behavior Volume 35 Number 6 November • December 2003295
A better understanding of important psychosocial vari-
ables that influence dietary behavior is needed to develop
effective interventions involving an increase in dairy prod-
uct consumption by older adults. Use of an appropriate the-
oretical framework provides structure to the identification of
factors influencing dairy product consumption.The Theory
of Planned Behavior (TPB) has recently been used to iden-
tify important factors influencing dairy product intake by
young women eligible for the WIC program,6 healthful eat-
ing by adolescents,7 and fruit and vegetable consumption.8
Based on a meta-analysis involving 185 independent studies,
the TPB accounted for 27% and 38% of the variance in
behavior and intention, respectively,9 which was comparable
to the predictive ability of other theories that have been used
in relation to dietary behaviors.10
The TPB includes 3 constructs that explain intention to
perform health behaviors (Figure).11,12
They include attitudes
toward the behavior, subjective norms, and perceived behav-
ioral control. Attitudes are determined by beliefs about the
likelihood of outcomes and their importance.Subjective
norms are determined by what others think the individual
should do and the individual’s motivation to comply. Per-
ceived behavioral control is determined by control beliefs
that can facilitate or inhibit the behavior, such as internal
factors (skills, abilities) and external factors (opportunities,
barriers). Both intention and perceived behavioral control
have direct influence on behavior.
Inadequate consumption of dairy products may be related
to low calcium intake for older adults. In the present study,
the TPB was used to explain intention to consume as we
consumption of dairy products among older adults by ex
ining factors including attitudes, subjective norms, and p
ceived behavioral control.Addressing important factors t
predict consumption of dairy products by older adults m
contribute to improved effectiveness of educational effo
targeted to this population.
METHODS
Study Design and Subjects
This study used a cross-sectional questionnaire desig
Initial individual interviews using open-ended questio
were conducted with 33 older adults to obtain informatio
necessary to develop the questionnaire. Subjects comple
ing the questionnaire were recruited from 7 commu
centers in the Minneapolis-St.Paul metropolitan area.
Those who participated in initial interviews were not ask
to complete the questionnaire. Investigators recruited 19
older adults (aged 65 years or older).Some provided
incomplete information (n = 20); another 15 individuals
did not meet the age criteria.The final sample included 1
older adults.
Measures Used in the Questionnaire
The questionnaire was developed according to the steps
gested by Montano et al12and Ajzen and Madden13 based on
Behavioral beliefs
(eg, Eating dairy products
regularly helps me have a
balanced diet.)
Attitude toward
consuming dairy
products
Subjective norm
(social influence)
Intention to
consume dairy
products
Dairy product
consumption
Normative beliefs
(eg, My doctor thinks I
should drink/eat dairy
products.)
Motivation to comply
(eg, I want to comply with
doctor.)
Perceived control
over consuming
dairy products
Control beliefs
(eg, It is difficult to keep
dairy products always avail-
able in my home.)
Figure. Proposed relationship between variables in this study based on the Theory of Planned Behavior.
A better understanding of important psychosocial vari-
ables that influence dietary behavior is needed to develop
effective interventions involving an increase in dairy prod-
uct consumption by older adults. Use of an appropriate the-
oretical framework provides structure to the identification of
factors influencing dairy product consumption.The Theory
of Planned Behavior (TPB) has recently been used to iden-
tify important factors influencing dairy product intake by
young women eligible for the WIC program,6 healthful eat-
ing by adolescents,7 and fruit and vegetable consumption.8
Based on a meta-analysis involving 185 independent studies,
the TPB accounted for 27% and 38% of the variance in
behavior and intention, respectively,9 which was comparable
to the predictive ability of other theories that have been used
in relation to dietary behaviors.10
The TPB includes 3 constructs that explain intention to
perform health behaviors (Figure).11,12
They include attitudes
toward the behavior, subjective norms, and perceived behav-
ioral control. Attitudes are determined by beliefs about the
likelihood of outcomes and their importance.Subjective
norms are determined by what others think the individual
should do and the individual’s motivation to comply. Per-
ceived behavioral control is determined by control beliefs
that can facilitate or inhibit the behavior, such as internal
factors (skills, abilities) and external factors (opportunities,
barriers). Both intention and perceived behavioral control
have direct influence on behavior.
Inadequate consumption of dairy products may be related
to low calcium intake for older adults. In the present study,
the TPB was used to explain intention to consume as we
consumption of dairy products among older adults by ex
ining factors including attitudes, subjective norms, and p
ceived behavioral control.Addressing important factors t
predict consumption of dairy products by older adults m
contribute to improved effectiveness of educational effo
targeted to this population.
METHODS
Study Design and Subjects
This study used a cross-sectional questionnaire desig
Initial individual interviews using open-ended questio
were conducted with 33 older adults to obtain informatio
necessary to develop the questionnaire. Subjects comple
ing the questionnaire were recruited from 7 commu
centers in the Minneapolis-St.Paul metropolitan area.
Those who participated in initial interviews were not ask
to complete the questionnaire. Investigators recruited 19
older adults (aged 65 years or older).Some provided
incomplete information (n = 20); another 15 individuals
did not meet the age criteria.The final sample included 1
older adults.
Measures Used in the Questionnaire
The questionnaire was developed according to the steps
gested by Montano et al12and Ajzen and Madden13 based on
Behavioral beliefs
(eg, Eating dairy products
regularly helps me have a
balanced diet.)
Attitude toward
consuming dairy
products
Subjective norm
(social influence)
Intention to
consume dairy
products
Dairy product
consumption
Normative beliefs
(eg, My doctor thinks I
should drink/eat dairy
products.)
Motivation to comply
(eg, I want to comply with
doctor.)
Perceived control
over consuming
dairy products
Control beliefs
(eg, It is difficult to keep
dairy products always avail-
able in my home.)
Figure. Proposed relationship between variables in this study based on the Theory of Planned Behavior.
the information obtained from initial interviews with 33
older adults.
Attitudes toward consuming dairy products.During
the initial individual interviews,older adults (n = 33)
responded to open-ended questions regarding the benefits
and advantages or disadvantages related to eating dairy
products. After counting frequencies and reviewing the
responses,19 items were selected to measure behavioral
beliefs. These items included nutritional benefits (such as
strong bones, balanced meals, vitamins, and minerals), prac-
tical reasons for eating dairy foods (such as taste, going well
with other foods, providing a snack), and disadvantages of
eating dairy foods (such as make me feel sick, high in fat or
cholesterol).
Each item was designed to be measured on a 5-point
scale (very unlikely to very likely) to indicate the strength of
these beliefs. Outcome evaluation, which is the other com-
ponent comprising attitudes in the TPB, was not considered
in this study because prior experience indicated that most
people similarly evaluate the outcome of behavior.14 Atti-
tudes toward consuming dairy products were defined as the
summated score of the 19 behavioral beliefs.The Cronbach
coefficientα15 was .82 and was considered acceptable for the
attitudes scale.
Subjective norms.Thirteen different significant others
or information sources were listed by older adults during the
initial individual interviews as having an influence over dairy
product consumption.These were categorized into 7 groups:
family members (daughters/sons, sisters/brothers), spouse,
friends, doctor, cooks at senior centers, television programs,
and newspapers/magazines. Items for normative beliefs were
rated on a 5-point scale (very unlikely to very likely).The cor-
responding motivation to comply with each significant other
or source of information was measured on a 5-point scale
(not at all to very much).There was also a response category
for subjects to check if these significant others did not apply
to the subjects,for example,if the person did not have a spouse
or never watched television.This response category was coded
as a neutral point.The subjective norms variable was defined
as the summated score of the product of each normative belief
and motivation to comply.The Cronbach coefficientα was
.81 for this scale and was considered acceptable.
Perceived behavioral control over consuming dairy
products.During the initial interviews, subjects identi-
fied factors or situations that made it difficult to consume
dairy products.Similar responses were grouped together,
resulting in 21 items to measure control beliefs. These
included perceived confidence in eating dairy foods (such as
for snacks, milk-based desserts, low-fat products, eating with
meals), confidence in eating dairy foods in several different
situations (such as when eating out, whenever you want to),
and availability issues and access to dairy foods.These items
were rated on 5-point scales (disagree a lot to agree a lot or
very difficult to very easy). Perceived behavioral control
consuming dairy products was defined as the summ
score of control beliefs.The Cronbach coefficientα for this
scale was .90 and was also considered acceptable.
Intention.Two items were used to measure intention to
consume dairy products.The item,“How likely is it that yo
will eat dairy products regularly (2-3 servings a day) for
next month?” was rated on a 5-point scale (very unlikely
very likely).The other item was “How many servings of d
products do you plan to eat for the next month?”and had
points from never/rarely to more than 3 servings a day.In
tion was defined as the summated score of the 2 items.
Dairy product consumption.Dairy product consump-
tion was measured using food items in Block’s Food Fre-
quency Questionnaire.16Ten food items were used, includ-
ing milk,milk on cereal,cheese,and yogurt.To measure d
product consumption more accurately, milk or cheese us
in cooking foods was also included. Subjects were asked
indicate how often and how much they usually ate for ea
food item. Dairy product consumption was quantified as
number of servings consumed per day.
A preliminary draft of the questionnaire was reviewed
3 university professionals and pilot tested with 5 older a
to check understanding of items. Based on the pilot
minor changes were made in format and wording.The st
was approved by the Human Subjects Protection Commi
tee of the University of Minnesota’s Institutional Review
Board.
Data Collection
Data were collected after meals at congregate dining ce
or after classes or meetings in community centers betwe
November 2001 and May 2002. The food frequency ques
tionnaire items regarding dairy products were compl
prior to completion of the measures related to the 3 vari
proposed in the TPB. In most cases, the food frequency i
were administered by investigators through personal int
views,followed by subjects responding to the remaini
items without assistance.However,some subjects (about
needed assistance because they had difficulty either rea
marking the questionnaire. It took 20 to 30 minutes for m
of the older adults to complete the questionnaire.
Statistical Analysis
Data were analyzed using the Statistical Analysis Sys
(SAS, Version 6.12,Cary,NC). Descriptive statistics were
used to examine demographic characteristics and study
ables. Student’s t-tests were done to determine differenc
dairy product consumption according to demographic va
able categories. Correlation analysis was used to examin
simple association between study variables.To investiga
association between the scales for the 3 variables propo
the TPB and intention to consume and consumption
296 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
older adults.
Attitudes toward consuming dairy products.During
the initial individual interviews,older adults (n = 33)
responded to open-ended questions regarding the benefits
and advantages or disadvantages related to eating dairy
products. After counting frequencies and reviewing the
responses,19 items were selected to measure behavioral
beliefs. These items included nutritional benefits (such as
strong bones, balanced meals, vitamins, and minerals), prac-
tical reasons for eating dairy foods (such as taste, going well
with other foods, providing a snack), and disadvantages of
eating dairy foods (such as make me feel sick, high in fat or
cholesterol).
Each item was designed to be measured on a 5-point
scale (very unlikely to very likely) to indicate the strength of
these beliefs. Outcome evaluation, which is the other com-
ponent comprising attitudes in the TPB, was not considered
in this study because prior experience indicated that most
people similarly evaluate the outcome of behavior.14 Atti-
tudes toward consuming dairy products were defined as the
summated score of the 19 behavioral beliefs.The Cronbach
coefficientα15 was .82 and was considered acceptable for the
attitudes scale.
Subjective norms.Thirteen different significant others
or information sources were listed by older adults during the
initial individual interviews as having an influence over dairy
product consumption.These were categorized into 7 groups:
family members (daughters/sons, sisters/brothers), spouse,
friends, doctor, cooks at senior centers, television programs,
and newspapers/magazines. Items for normative beliefs were
rated on a 5-point scale (very unlikely to very likely).The cor-
responding motivation to comply with each significant other
or source of information was measured on a 5-point scale
(not at all to very much).There was also a response category
for subjects to check if these significant others did not apply
to the subjects,for example,if the person did not have a spouse
or never watched television.This response category was coded
as a neutral point.The subjective norms variable was defined
as the summated score of the product of each normative belief
and motivation to comply.The Cronbach coefficientα was
.81 for this scale and was considered acceptable.
Perceived behavioral control over consuming dairy
products.During the initial interviews, subjects identi-
fied factors or situations that made it difficult to consume
dairy products.Similar responses were grouped together,
resulting in 21 items to measure control beliefs. These
included perceived confidence in eating dairy foods (such as
for snacks, milk-based desserts, low-fat products, eating with
meals), confidence in eating dairy foods in several different
situations (such as when eating out, whenever you want to),
and availability issues and access to dairy foods.These items
were rated on 5-point scales (disagree a lot to agree a lot or
very difficult to very easy). Perceived behavioral control
consuming dairy products was defined as the summ
score of control beliefs.The Cronbach coefficientα for this
scale was .90 and was also considered acceptable.
Intention.Two items were used to measure intention to
consume dairy products.The item,“How likely is it that yo
will eat dairy products regularly (2-3 servings a day) for
next month?” was rated on a 5-point scale (very unlikely
very likely).The other item was “How many servings of d
products do you plan to eat for the next month?”and had
points from never/rarely to more than 3 servings a day.In
tion was defined as the summated score of the 2 items.
Dairy product consumption.Dairy product consump-
tion was measured using food items in Block’s Food Fre-
quency Questionnaire.16Ten food items were used, includ-
ing milk,milk on cereal,cheese,and yogurt.To measure d
product consumption more accurately, milk or cheese us
in cooking foods was also included. Subjects were asked
indicate how often and how much they usually ate for ea
food item. Dairy product consumption was quantified as
number of servings consumed per day.
A preliminary draft of the questionnaire was reviewed
3 university professionals and pilot tested with 5 older a
to check understanding of items. Based on the pilot
minor changes were made in format and wording.The st
was approved by the Human Subjects Protection Commi
tee of the University of Minnesota’s Institutional Review
Board.
Data Collection
Data were collected after meals at congregate dining ce
or after classes or meetings in community centers betwe
November 2001 and May 2002. The food frequency ques
tionnaire items regarding dairy products were compl
prior to completion of the measures related to the 3 vari
proposed in the TPB. In most cases, the food frequency i
were administered by investigators through personal int
views,followed by subjects responding to the remaini
items without assistance.However,some subjects (about
needed assistance because they had difficulty either rea
marking the questionnaire. It took 20 to 30 minutes for m
of the older adults to complete the questionnaire.
Statistical Analysis
Data were analyzed using the Statistical Analysis Sys
(SAS, Version 6.12,Cary,NC). Descriptive statistics were
used to examine demographic characteristics and study
ables. Student’s t-tests were done to determine differenc
dairy product consumption according to demographic va
able categories. Correlation analysis was used to examin
simple association between study variables.To investiga
association between the scales for the 3 variables propo
the TPB and intention to consume and consumption
296 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
Journal of Nutrition Education and Behavior Volume 35 Number 6 November • December 2003297
dairy products, regression analyses were done, first to predict
intention to consume and then to predict dairy product con-
sumption.To examine the relative importance of each vari-
able in explaining variance in the dependent variable, the
square of the standardizedβ for each variable was obtained
and the ratio of each standardizedβ was examined.17A level
of P < .05 was considered significant for statistical tests.
RESULTS
Descriptive Statistics
The mean age of subjects was 75.1 years (SD 6.1 years). Sub-
jects were mostly women (76%) and white (65%).About half
of the subjects had less than a high school education or had
completed high school.Forty-six percent lived alone,whereas
38% lived with a spouse. Most rated their health as good or
very good. Demographic data are presented in Table 1.
The mean of the summated intention items was 0.67 ±
2.13 from a possible score of 4 to +4, suggesting that sub-
jects were slightly positive about their willingness to con
sume dairy products. On average, older adults consume
(SD 1.3) servings of dairy products per day.When the dis
bution of dairy product consumption was examined, 21%
had less than 1 serving of dairy foods, 29% had 1 to less
2 servings of dairy foods, 27% ate 2 to less than 3 servin
and only 15% had 3 to less than 4 servings.
Among the categorical variables,race,use of suppleme
and regular exercise were related to dairy product consu
tion (see Table 1).White subjects consumed greater num
of servings of dairy foods than other groups. Individuals
were more likely to consume greater numbers of serving
dairy foods used supplements and exercised regularly.
The simple association between study variables w
examined using Pearson correlation coefficients (Table 2
Dairy product consumption was highly correlated with th
intention to consume dairy products (r = .61, P < .001) a
perceived behavioral control over consuming dairy produ
(r = .48, P < .001). Intention to consume dairy products
significantly related to the 3 variables proposed in the TP
in the order of decreasing magnitude of association: atti
Table 1. Comparison of Dairy Product Consumption by Demographic Variables †
Mean Standard
Variables N % (servings/d) Error F Value
Gender
Female 123 75.9 2.06 0.12 1.17
Male 39 24.1 2.32 0.19
Race
White 106 65.4 2.36a‡ 0.13 8.19**
African American 35 21.6 1.38b 0.17
Other 21 12.9 2.15a 0.28
Education level §
≤12th 78 48.1 2.00 0.15 2.04
> 12th 74 45.7 2.30 0.15
Marital status
Married 65 40.1 2.39 0.15 2.28
Single 16 9.9 1.59 0.34
Widowed 57 35.2 2.14 0.17
Divorced/separated 24 14.8 1.83 0.27
Living status
Alone 74 45.7 1.98 0.16 1.32
With spouse 61 37.7 2.26 0.15
With other family members 27 16.6 2.23 0.26
Regular use of supplement
No 49 30.2 1.79a 0.19 4.71*
Yes 113 69.8 2.27b 0.12
Regular exercise
No 48 29.6 1.60a 0.14 15.80***
Yes 114 70.4 2.35b 0.13
*P < .05; ** P < .01; *** P < .001.
†By analysis of variance.
‡Using Tukey’s method of comparison.
§Ten people (6.2%) did not respond to the question about education level.
Values with different superscript letters are significantly different.
dairy products, regression analyses were done, first to predict
intention to consume and then to predict dairy product con-
sumption.To examine the relative importance of each vari-
able in explaining variance in the dependent variable, the
square of the standardizedβ for each variable was obtained
and the ratio of each standardizedβ was examined.17A level
of P < .05 was considered significant for statistical tests.
RESULTS
Descriptive Statistics
The mean age of subjects was 75.1 years (SD 6.1 years). Sub-
jects were mostly women (76%) and white (65%).About half
of the subjects had less than a high school education or had
completed high school.Forty-six percent lived alone,whereas
38% lived with a spouse. Most rated their health as good or
very good. Demographic data are presented in Table 1.
The mean of the summated intention items was 0.67 ±
2.13 from a possible score of 4 to +4, suggesting that sub-
jects were slightly positive about their willingness to con
sume dairy products. On average, older adults consume
(SD 1.3) servings of dairy products per day.When the dis
bution of dairy product consumption was examined, 21%
had less than 1 serving of dairy foods, 29% had 1 to less
2 servings of dairy foods, 27% ate 2 to less than 3 servin
and only 15% had 3 to less than 4 servings.
Among the categorical variables,race,use of suppleme
and regular exercise were related to dairy product consu
tion (see Table 1).White subjects consumed greater num
of servings of dairy foods than other groups. Individuals
were more likely to consume greater numbers of serving
dairy foods used supplements and exercised regularly.
The simple association between study variables w
examined using Pearson correlation coefficients (Table 2
Dairy product consumption was highly correlated with th
intention to consume dairy products (r = .61, P < .001) a
perceived behavioral control over consuming dairy produ
(r = .48, P < .001). Intention to consume dairy products
significantly related to the 3 variables proposed in the TP
in the order of decreasing magnitude of association: atti
Table 1. Comparison of Dairy Product Consumption by Demographic Variables †
Mean Standard
Variables N % (servings/d) Error F Value
Gender
Female 123 75.9 2.06 0.12 1.17
Male 39 24.1 2.32 0.19
Race
White 106 65.4 2.36a‡ 0.13 8.19**
African American 35 21.6 1.38b 0.17
Other 21 12.9 2.15a 0.28
Education level §
≤12th 78 48.1 2.00 0.15 2.04
> 12th 74 45.7 2.30 0.15
Marital status
Married 65 40.1 2.39 0.15 2.28
Single 16 9.9 1.59 0.34
Widowed 57 35.2 2.14 0.17
Divorced/separated 24 14.8 1.83 0.27
Living status
Alone 74 45.7 1.98 0.16 1.32
With spouse 61 37.7 2.26 0.15
With other family members 27 16.6 2.23 0.26
Regular use of supplement
No 49 30.2 1.79a 0.19 4.71*
Yes 113 69.8 2.27b 0.12
Regular exercise
No 48 29.6 1.60a 0.14 15.80***
Yes 114 70.4 2.35b 0.13
*P < .05; ** P < .01; *** P < .001.
†By analysis of variance.
‡Using Tukey’s method of comparison.
§Ten people (6.2%) did not respond to the question about education level.
Values with different superscript letters are significantly different.
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toward consuming dairy products, perceived behavioral con-
trol, and subjective norms.
Regression Analyses for Intention to Consume Milk
The multiple regression model explained 42.4% of the vari-
ance in intention (F = 40.5, P < .0001), providing empirical
evidence for the TPB regarding dairy product consumption
by older adults (Table 3).Attitudes toward consuming dairy
products and perceived behavioral control were related to
intention,whereas subjective norms were not related. To
examine the relative importance of these variables in
explaining intention, the ratio of the square of the standard-
izedβ for each variable was examined. Attitudes account
for 1.6 times more variation in intention than perce
behavioralcontrol over consuming dairy products
(0.382/0.302).
Regression analyses were also completed while contro
ling for demographic variables. There were difference
intention, attitudes, and perceived behavioral control sco
by race and supplement use.In the preliminary analysis,
white subjects and those who used supplements reg
had greater intention and more favorable attitudes and f
more control over consuming dairy products than th
counterparts.Thus, a second regression to predict intent
was completed while controlling for race and supplemen
298 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
Table 2. Correlation among Study Variables
Dairy Product Consumption Intention Attitudes Subjective Norms Perceived Behavioral Control
Dairy product consumption 1.0
Intention 0.61*** 1.0
Attitudes 0.42*** 0.60*** 1.0
Subjective norms 0.33*** 0.38*** 0.49*** 1.0
Perceived behavioral control 0.48*** 0.55*** 0.55*** 0.31*** 1.0
***P < .001.
Table 3. Multiple Regression of Intention to Consume Dairy Products and Dairy Product Consumption on Selected Variables Based on the
Theory of Planned Behavior
Variables SE Standardized t Model R 2
Intention on Attitudes, Subjective Norms, and Perceived Behavioral Control
Model 1 †
Attitudes 0.08 0.02 0.38 4.90*** .424
Subjective norms 0.02 0.01 0.11 1.55
Perceived behavioral control 0.05 0.01 0.30 4.19***
Model 2 ‡
Attitudes 0.07 0.02 0.37 4.70*** .434
Subjective norms 0.02 0.01 0.11 1.59
Perceived behavioral control 0.04 0.01 0.26 3.53***
Race 0.24 0.29 0.05 0.85
Supplement use 0.57 0.28 0.12 2.03*
Consumption on Intention and Perceived Behavioral Control
Model 1 §
Intention 0.30 0.05 0.49 6.67*** .394
Perceived behavioral control 0.02 0.01 0.22 2.96**
Model 2 ||
Intention 0.30 0.05 0.48 6.47*** .390
Perceived behavioral control 0.02 0.01 0.20 2.56*
Race 0.19 0.18 0.07 1.08
Supplement use 0.01 0.19 0.00 0.05
*P < .05; **P < .01; ***P < .001.
†Model df = 3,158; model F = 40.5; P = .0001.
‡Controlling for race and supplement use; model df = 5,156; model F = 25.7; P = .0001.
§Model df = 2,159; model F = 53.2; P = .0001.
||Controlling for race and supplement use; model df = 4,157; model F = 26.8; P = .0001
trol, and subjective norms.
Regression Analyses for Intention to Consume Milk
The multiple regression model explained 42.4% of the vari-
ance in intention (F = 40.5, P < .0001), providing empirical
evidence for the TPB regarding dairy product consumption
by older adults (Table 3).Attitudes toward consuming dairy
products and perceived behavioral control were related to
intention,whereas subjective norms were not related. To
examine the relative importance of these variables in
explaining intention, the ratio of the square of the standard-
izedβ for each variable was examined. Attitudes account
for 1.6 times more variation in intention than perce
behavioralcontrol over consuming dairy products
(0.382/0.302).
Regression analyses were also completed while contro
ling for demographic variables. There were difference
intention, attitudes, and perceived behavioral control sco
by race and supplement use.In the preliminary analysis,
white subjects and those who used supplements reg
had greater intention and more favorable attitudes and f
more control over consuming dairy products than th
counterparts.Thus, a second regression to predict intent
was completed while controlling for race and supplemen
298 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
Table 2. Correlation among Study Variables
Dairy Product Consumption Intention Attitudes Subjective Norms Perceived Behavioral Control
Dairy product consumption 1.0
Intention 0.61*** 1.0
Attitudes 0.42*** 0.60*** 1.0
Subjective norms 0.33*** 0.38*** 0.49*** 1.0
Perceived behavioral control 0.48*** 0.55*** 0.55*** 0.31*** 1.0
***P < .001.
Table 3. Multiple Regression of Intention to Consume Dairy Products and Dairy Product Consumption on Selected Variables Based on the
Theory of Planned Behavior
Variables SE Standardized t Model R 2
Intention on Attitudes, Subjective Norms, and Perceived Behavioral Control
Model 1 †
Attitudes 0.08 0.02 0.38 4.90*** .424
Subjective norms 0.02 0.01 0.11 1.55
Perceived behavioral control 0.05 0.01 0.30 4.19***
Model 2 ‡
Attitudes 0.07 0.02 0.37 4.70*** .434
Subjective norms 0.02 0.01 0.11 1.59
Perceived behavioral control 0.04 0.01 0.26 3.53***
Race 0.24 0.29 0.05 0.85
Supplement use 0.57 0.28 0.12 2.03*
Consumption on Intention and Perceived Behavioral Control
Model 1 §
Intention 0.30 0.05 0.49 6.67*** .394
Perceived behavioral control 0.02 0.01 0.22 2.96**
Model 2 ||
Intention 0.30 0.05 0.48 6.47*** .390
Perceived behavioral control 0.02 0.01 0.20 2.56*
Race 0.19 0.18 0.07 1.08
Supplement use 0.01 0.19 0.00 0.05
*P < .05; **P < .01; ***P < .001.
†Model df = 3,158; model F = 40.5; P = .0001.
‡Controlling for race and supplement use; model df = 5,156; model F = 25.7; P = .0001.
§Model df = 2,159; model F = 53.2; P = .0001.
||Controlling for race and supplement use; model df = 4,157; model F = 26.8; P = .0001
use. This model explained 43.4% of the variance in inten-
tion.Similar to the first model,attitudes and perceived
behavioral control were associated with intention; however,
the relative importance of perceived behavioral control in
explaining intention was slightly decreased.Attitudes
explained 2 times more variation in intention than perceived
behavioral control over consuming dairy products.
Regression Analyses for Dairy Product Consumption
Intention to consume and perceived behavioral control
explained 39.4% of the variation in dairy product consump-
tion (see Table 3).As proposed in the TPB, perceived behav-
ioral control directly contributed to the actual consumption
of dairy products. In the preliminary analyses, race and sup-
plement use were related to dairy product consumption, as
well as intention to consume and perceived behavioral con-
trol. Therefore,another regression analysis was completed
while controlling for the effect of these variables (see Table
3).The variance explained by independent variables in this
model was almost the same as in the first model. However,
the relative importance of intention to consume compared
to perceived behavioral control was increased from 5.0 times
to 5.8 times.
DISCUSSION
Nutrition education that results in an increased intake of
calcium-rich foods such as dairy products is important in
the prevention of osteoporosis.Estimates indicate that
osteoporosis contributes to up to 90% of hip fractures in
women and 80% of hip fractures in men.18 A recent study
has shown that improvements in calcium intake provided as
3 servings of yogurt/day rapidly improved bone resorption
in older women.19 It has been estimated that increasing
bone mineral density by 5% could decrease the risk of frac-
tures by 25%.20Another study showed that increased intake
of dairy products by older adults resulted in overall
improvement in nutrient intakes.21 Interventions to increase
intake of dairy products with community-dwelling elders
have been successful22 and therefore should be expanded
based on appropriate theoretical models.The current study
contributes to this effort by further explaining dairy prod-
uct consumption by older adults based on a useful theoret-
ical model (TPB).
In this study,dairy product consumption for a conve-
nience sample of older adults was below recommendations
at about 2 servings per day. Using a nationally representative
sample involving 24-hour recall data, others have estimated
intake of dairy products by older adults to be about 1 serv-
ing per day.5,23
The demographic makeup of the convenience
sample and small sample size in the current study may
explain the difference in estimates of intake of dairy prod-
ucts.White subjects had greater intention to consume dairy
products and more favorable attitudes, felt more control over
consuming dairy products,and had greater consumption
than other subjects. Issues with lactose intolerance amo
African American subjects may be partially responsible f
these differences. A study by Elbon et al showed that pe
ceived milk intolerance was more common among o
African American adults (35%) who consumed less milk a
other dairy products compared with older white adu
(17%).24African American mothers participating in the Spe
cial Supplemental Program for Women, Infants and Child
(WIC) also consumed less milk compared with white mot
ers, which was thought to be the result of less favorable
tudes and intention based on the TPB.6
The influence of the 3 variables proposed in the TPB o
intention and behavior is thought to be dependent on th
particular behavior and situation.25 In situations in which
attitudes are strong or normative beliefs are powerful, a
tudes or subjective norms may be more predictive t
perceived behavioral control. In the current study, applic
tion of the TPB among a sample of older adults showed t
attitudes toward eating dairy products and perceived be
ioral control contributed to the model for predicting inten
tion, whereas subjective norms did not,indicating that
normative beliefs were not particularly powerful in t
group. This is consistent with several other studies o
application of the TPB in relation to diet and other health
related behaviors in which attitudes and perceived beha
control are more significant than subjective norms.7,26
Older adults may not be as influenced by others in ter
of subjective norms because many live alone and have le
contact with reference groups,such as family or friends.
They may also be more likely to depend on their own de
sion-making ability regarding food choices rather tha
others because of their considerable life experiences. It f
lows that there may not be many powerful social influen
for increasing intake of dairy products for this population
the current study,there was no significant relationship
between dairy product intake and living status (about 54
indicated that they lived with others). In other studies, li
arrangements have been shown to affect overall diet qu
among white adults,27 with those living with a spouse having
better diet quality. However, the current study was focus
on dairy products only and did not measure overall
quality and nutrient intake.
The relationship between perceived behavioral con
and intention is also dependent on the behavior and situ
tion.25 In the current study, perceived behavioral control a
intention were well correlated (r = .55, P < .001), indicat
that the subjects may have been more likely to wa
engage in the behavior if they thought there were fewer
sonal and environmental barriers. Examples of these bar
included difficulty substituting milk for other beverag
finding transportation to the store to purchase dairy prod
ucts, not always being able to have dairy products availa
in the home, and cost. The relationship between intentio
and behavior was also strong (r = .61, P < .001). In some
uations,it may be difficult for intention to translate in
behavior if various personal and environmental contr
Journal of Nutrition Education and Behavior Volume 35 Number 6 November • December 2003299
tion.Similar to the first model,attitudes and perceived
behavioral control were associated with intention; however,
the relative importance of perceived behavioral control in
explaining intention was slightly decreased.Attitudes
explained 2 times more variation in intention than perceived
behavioral control over consuming dairy products.
Regression Analyses for Dairy Product Consumption
Intention to consume and perceived behavioral control
explained 39.4% of the variation in dairy product consump-
tion (see Table 3).As proposed in the TPB, perceived behav-
ioral control directly contributed to the actual consumption
of dairy products. In the preliminary analyses, race and sup-
plement use were related to dairy product consumption, as
well as intention to consume and perceived behavioral con-
trol. Therefore,another regression analysis was completed
while controlling for the effect of these variables (see Table
3).The variance explained by independent variables in this
model was almost the same as in the first model. However,
the relative importance of intention to consume compared
to perceived behavioral control was increased from 5.0 times
to 5.8 times.
DISCUSSION
Nutrition education that results in an increased intake of
calcium-rich foods such as dairy products is important in
the prevention of osteoporosis.Estimates indicate that
osteoporosis contributes to up to 90% of hip fractures in
women and 80% of hip fractures in men.18 A recent study
has shown that improvements in calcium intake provided as
3 servings of yogurt/day rapidly improved bone resorption
in older women.19 It has been estimated that increasing
bone mineral density by 5% could decrease the risk of frac-
tures by 25%.20Another study showed that increased intake
of dairy products by older adults resulted in overall
improvement in nutrient intakes.21 Interventions to increase
intake of dairy products with community-dwelling elders
have been successful22 and therefore should be expanded
based on appropriate theoretical models.The current study
contributes to this effort by further explaining dairy prod-
uct consumption by older adults based on a useful theoret-
ical model (TPB).
In this study,dairy product consumption for a conve-
nience sample of older adults was below recommendations
at about 2 servings per day. Using a nationally representative
sample involving 24-hour recall data, others have estimated
intake of dairy products by older adults to be about 1 serv-
ing per day.5,23
The demographic makeup of the convenience
sample and small sample size in the current study may
explain the difference in estimates of intake of dairy prod-
ucts.White subjects had greater intention to consume dairy
products and more favorable attitudes, felt more control over
consuming dairy products,and had greater consumption
than other subjects. Issues with lactose intolerance amo
African American subjects may be partially responsible f
these differences. A study by Elbon et al showed that pe
ceived milk intolerance was more common among o
African American adults (35%) who consumed less milk a
other dairy products compared with older white adu
(17%).24African American mothers participating in the Spe
cial Supplemental Program for Women, Infants and Child
(WIC) also consumed less milk compared with white mot
ers, which was thought to be the result of less favorable
tudes and intention based on the TPB.6
The influence of the 3 variables proposed in the TPB o
intention and behavior is thought to be dependent on th
particular behavior and situation.25 In situations in which
attitudes are strong or normative beliefs are powerful, a
tudes or subjective norms may be more predictive t
perceived behavioral control. In the current study, applic
tion of the TPB among a sample of older adults showed t
attitudes toward eating dairy products and perceived be
ioral control contributed to the model for predicting inten
tion, whereas subjective norms did not,indicating that
normative beliefs were not particularly powerful in t
group. This is consistent with several other studies o
application of the TPB in relation to diet and other health
related behaviors in which attitudes and perceived beha
control are more significant than subjective norms.7,26
Older adults may not be as influenced by others in ter
of subjective norms because many live alone and have le
contact with reference groups,such as family or friends.
They may also be more likely to depend on their own de
sion-making ability regarding food choices rather tha
others because of their considerable life experiences. It f
lows that there may not be many powerful social influen
for increasing intake of dairy products for this population
the current study,there was no significant relationship
between dairy product intake and living status (about 54
indicated that they lived with others). In other studies, li
arrangements have been shown to affect overall diet qu
among white adults,27 with those living with a spouse having
better diet quality. However, the current study was focus
on dairy products only and did not measure overall
quality and nutrient intake.
The relationship between perceived behavioral con
and intention is also dependent on the behavior and situ
tion.25 In the current study, perceived behavioral control a
intention were well correlated (r = .55, P < .001), indicat
that the subjects may have been more likely to wa
engage in the behavior if they thought there were fewer
sonal and environmental barriers. Examples of these bar
included difficulty substituting milk for other beverag
finding transportation to the store to purchase dairy prod
ucts, not always being able to have dairy products availa
in the home, and cost. The relationship between intentio
and behavior was also strong (r = .61, P < .001). In some
uations,it may be difficult for intention to translate in
behavior if various personal and environmental contr
Journal of Nutrition Education and Behavior Volume 35 Number 6 November • December 2003299
factors inhibit the behavior. A strength of the TPB in the
current study is that perceived inhibitory factors are an
important part of the model and can be identified in order
of their relevance in prediction of behavior.This can be very
useful in developing dietary behavior change interventions
that address personal and environmental barriers.
In the current study, perceived behavioral control con-
tributed to intention to consume and actual consumption of
dairy products,confirming the findings of other studies
applying the TPB to dietary behavior.8,26,28Perceived behav-
ioral control is thought to be predicted by items concerned
with external control such as the barriers of cost and avail-
ability, whereas self-efficacy was predicted by both internal
items, such as motivation and knowledge and external items.
In the current study, the perceived behavioral control scale
included both internal items, such as perceived abilities and
external items, as suggested in the theory. Others have exam-
ined the concepts of perceived behavioral control and self-
efficacy as separate from each other8,9and suggest more care-
ful definition of these concepts in future studies.
The predictive power for both intention and behavior
based on the TPB in the current study can be compared with
the results from other recent studies focusing on health-
related behaviors.7,26,28,29
In a study of milk consumption by
young pregnant women, the TPB model explained 36% of
the variance in intention and 46% of the variance in behav-
ior. In the current study with older adults, the model was
about as predictive (42% of the variance in intention,whereas
intention and perceived behavioral control explained 39% of
the variance in behavior).The predictive power of the model
was not as strong in studies involving consumption of other
foods or more complex behaviors. For example, the TPB
model explained 31% for the variance in intention and only
7% of the variance in behavior related to fruit and vegetable
consumption among adolescents.7 In another recent study
with adolescents, intention explained 17% of the variance in
healthful dietary behavior involving total calorie intake, per-
centage of calories from fat, and intake of fruits and vegeta-
bles,28 whereas attitudes, norms, and perceived behavioral
control explained 42% of the variance in intention. From
these results, it is clear that the model best predicts behavior
if the behavior is more specific (milk versus dairy products or
dairy products versus fruits and vegetables).10
A limitation to this study is that the results are based on a
small convenience sample of older adults attending senior
centers. Thus,the findings are not generalizable to other
groups of seniors (eg, frail elderly or those in other geo-
graphic areas).
IMPLICATIONS FOR RESEARCH AND
PRACTICE
The results of this study showed the importance of perceived
behavioral control; therefore, further research is needed to
understand what influences perceived behavioral control and
how to increase the perception of control. In terms of pra
tice, nutrition educators might focus on factors examine
this study in planning educational programs for older ad
such as having favorable attitudes (emphasize advantag
minimize disadvantages of consuming dairy products) an
increasing the perception of control over consuming dair
products.To help older adults have favorable attitudes, p
titioners need to address nutritional benefits (eg, providi
calcium, vitamins, and other nutrients). Practical benefit
need to be addressed, such as the concepts that dairy p
ucts taste good, they can serve as beverages at breakfa
during the rest of the day, they help one to have a balan
diet, and they are foods that go well with other foods. In
addition, practitioners might help older adults increase p
ceived control in eating dairy foods with meals by substi
ing milk for other beverages and enhancing cooking skill
using dairy products. Environmental approaches are nee
to address the barriers of transportation, availability of d
products (at home), and cost.
These strategies will lead to changes in intention
hopefully help older adults consume more dairy product
was apparent from this study that there are multiple bel
factors that predict intention and behavior related to inta
of dairy products by older adults in this sample. Educatio
should therefore address these multiple constructs.
ACKNOWLEDGMENT
Funding for this project was obtained from the Minnesota
Agricultural Experiment Station (MIN –054-026).
REFERENCES
1. Food and Drug Administration and National Institutes of Health
Healthy People 2010: Understanding and Improving Health. 2nd ed
able at: http://www.health.gov/healthypeople. Accessed July 14, 20
2. Shea B, Wells G, Cranney A, et al. Meta-analysis of calcium supple-
mentation for the prevention of postmenopausal osteoporosis. End
Rev. 2002;23:552-559.
3. Wakimoto P, Block G. Dietary intake, dietary patterns, and changes
with age; an epidemiological perspective. J Gerontol Am Biol Sci Me
Sci. 2001;56:65-80.
4. Gerrior S, Bente L.Nutrient Content of the U.S. Food Supply, 1909-199
Washington, DC: US Dept. of Agriculture, Center for Nutrition Policy
and Promotion; 1997. Home Economics Research Report No. 53.
5. US Dept.of Agriculture, Agricultural Research Service.Food and
Nutrient Intakes by Individuals in the United States, by Sex and Ag
1996.Beltsville,Md: US Department of Agriculture, Agricultural
Research Science; 1998. Nationwide Food Surveys Report No. 96-2
6. Park K, Ureda JR. Specific motivations of milk consumption among
pregnant women enrolled in or eligible for WIC. J Nutr Educ. 1999;3
76-85.
7. Lien N, Lytle LA, Komro KA.Applying theory of planned behavior to
fruit and vegetable consumption of young adolescents. Sci Health
mot. 2002;16:189-197.
300 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
current study is that perceived inhibitory factors are an
important part of the model and can be identified in order
of their relevance in prediction of behavior.This can be very
useful in developing dietary behavior change interventions
that address personal and environmental barriers.
In the current study, perceived behavioral control con-
tributed to intention to consume and actual consumption of
dairy products,confirming the findings of other studies
applying the TPB to dietary behavior.8,26,28Perceived behav-
ioral control is thought to be predicted by items concerned
with external control such as the barriers of cost and avail-
ability, whereas self-efficacy was predicted by both internal
items, such as motivation and knowledge and external items.
In the current study, the perceived behavioral control scale
included both internal items, such as perceived abilities and
external items, as suggested in the theory. Others have exam-
ined the concepts of perceived behavioral control and self-
efficacy as separate from each other8,9and suggest more care-
ful definition of these concepts in future studies.
The predictive power for both intention and behavior
based on the TPB in the current study can be compared with
the results from other recent studies focusing on health-
related behaviors.7,26,28,29
In a study of milk consumption by
young pregnant women, the TPB model explained 36% of
the variance in intention and 46% of the variance in behav-
ior. In the current study with older adults, the model was
about as predictive (42% of the variance in intention,whereas
intention and perceived behavioral control explained 39% of
the variance in behavior).The predictive power of the model
was not as strong in studies involving consumption of other
foods or more complex behaviors. For example, the TPB
model explained 31% for the variance in intention and only
7% of the variance in behavior related to fruit and vegetable
consumption among adolescents.7 In another recent study
with adolescents, intention explained 17% of the variance in
healthful dietary behavior involving total calorie intake, per-
centage of calories from fat, and intake of fruits and vegeta-
bles,28 whereas attitudes, norms, and perceived behavioral
control explained 42% of the variance in intention. From
these results, it is clear that the model best predicts behavior
if the behavior is more specific (milk versus dairy products or
dairy products versus fruits and vegetables).10
A limitation to this study is that the results are based on a
small convenience sample of older adults attending senior
centers. Thus,the findings are not generalizable to other
groups of seniors (eg, frail elderly or those in other geo-
graphic areas).
IMPLICATIONS FOR RESEARCH AND
PRACTICE
The results of this study showed the importance of perceived
behavioral control; therefore, further research is needed to
understand what influences perceived behavioral control and
how to increase the perception of control. In terms of pra
tice, nutrition educators might focus on factors examine
this study in planning educational programs for older ad
such as having favorable attitudes (emphasize advantag
minimize disadvantages of consuming dairy products) an
increasing the perception of control over consuming dair
products.To help older adults have favorable attitudes, p
titioners need to address nutritional benefits (eg, providi
calcium, vitamins, and other nutrients). Practical benefit
need to be addressed, such as the concepts that dairy p
ucts taste good, they can serve as beverages at breakfa
during the rest of the day, they help one to have a balan
diet, and they are foods that go well with other foods. In
addition, practitioners might help older adults increase p
ceived control in eating dairy foods with meals by substi
ing milk for other beverages and enhancing cooking skill
using dairy products. Environmental approaches are nee
to address the barriers of transportation, availability of d
products (at home), and cost.
These strategies will lead to changes in intention
hopefully help older adults consume more dairy product
was apparent from this study that there are multiple bel
factors that predict intention and behavior related to inta
of dairy products by older adults in this sample. Educatio
should therefore address these multiple constructs.
ACKNOWLEDGMENT
Funding for this project was obtained from the Minnesota
Agricultural Experiment Station (MIN –054-026).
REFERENCES
1. Food and Drug Administration and National Institutes of Health
Healthy People 2010: Understanding and Improving Health. 2nd ed
able at: http://www.health.gov/healthypeople. Accessed July 14, 20
2. Shea B, Wells G, Cranney A, et al. Meta-analysis of calcium supple-
mentation for the prevention of postmenopausal osteoporosis. End
Rev. 2002;23:552-559.
3. Wakimoto P, Block G. Dietary intake, dietary patterns, and changes
with age; an epidemiological perspective. J Gerontol Am Biol Sci Me
Sci. 2001;56:65-80.
4. Gerrior S, Bente L.Nutrient Content of the U.S. Food Supply, 1909-199
Washington, DC: US Dept. of Agriculture, Center for Nutrition Policy
and Promotion; 1997. Home Economics Research Report No. 53.
5. US Dept.of Agriculture, Agricultural Research Service.Food and
Nutrient Intakes by Individuals in the United States, by Sex and Ag
1996.Beltsville,Md: US Department of Agriculture, Agricultural
Research Science; 1998. Nationwide Food Surveys Report No. 96-2
6. Park K, Ureda JR. Specific motivations of milk consumption among
pregnant women enrolled in or eligible for WIC. J Nutr Educ. 1999;3
76-85.
7. Lien N, Lytle LA, Komro KA.Applying theory of planned behavior to
fruit and vegetable consumption of young adolescents. Sci Health
mot. 2002;16:189-197.
300 Kim et al/THEORY OF PLANNED BEHAVIOR TO PREDICT DAIRY CONSUMPTION BY OLDER ADULTS
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Journal of Nutrition Education and Behavior Volume 35 Number 6 November • December 2003301
8. Povey R, Conner M, Sparks P,James R, Shepherd R. Application of
the theory of planned behavior to two dietary behaviors: roles of per-
ceived control and self-efficacy. Br J Health Psychol. 2000;5:121-139.
9. Armitage CJ, Conner M. Efficacy of the Theory of Planned Behaviour:
a meta-analytic review. Br J Soc Psychol. 2001;40:471-499.
10.Baranowski T,Cullen K,Baranowski J.Psychosocial correlates of dietary
intake: advancing dietary intervention. Annu Rev Nutr. 1999;19:17-40.
11.Conner M, Norman P. Predicting Health Behavior: Research and Practice
with Social Cognition Models. Abingdon, Oxon, UK: Open University
Press; 1996.
12.Montano DE, Kasprzyk D,Taplin SH.The Theory of Reasoned Action
and the Theory of Planned Behavior. In: Glanz K, Lewis RM, Rimer
BK, eds.Health Behavior and Health Education.San Francisco,Calif:
Jossey-Bass; 1997:85-112.
13.Ajzen I,Madden TJ.Prediction of goal-directed behavior:attitudes,inten-
tion,and perceived behavioral control.J Exp Soc Psychol.1986;22:453-474.
14.Ureda JR. Community intervention, creating opportunities and sup-
port for cancer control behavior. Cancer. 1993;72(suppl):1125-1131.
15.Nunnally JC,Bernstein IH.Psychometric Theory.New York,NY:
McGraw-Hill; 1994.
16.Berkeley Nutrition Services. Available at:http://www.nutrition-
quest.com/.Accessed May 21, 2003.
17.Kachigan SK. Statistical Analysis:An Interdisciplinary Introduction to Uni-
variate and Multivariate Methods.New York, NY: Radius Press; 1986.
18.Melton LJ 3rd, Thamer M,Ray NF,et al.Fractures attributable to
osteoporosis:report from the National Osteoporosis Foundation.J
Bone Miner Res. 1997;12:16-23.
19.Heaney RP,Rafferty K,Dowell MS.Effect of yogurt on a urinary
marker of bone resorption in postmenopausal women.J Am Diet Assoc.
2002;102:1672-1674.
20.Lips P.Prevention of hip fractures:drug therapy.Bone.1996;18
(suppl 3):159S-163S.
21.Barr SI, McCarron DA, Heaney RP, et al. Effects of increased con-
sumption of fluid milk on energy and nutrient intake, body weight,
cardiovascular risk factors in healthy older adults.J Am Diet Assoc.
2000;100:810-817.
22.Bernstein A, Nelson ME, Tucker KL, et al. A home-based nutrition
intervention to increase consumption of fruits,vegetables,and cal-
cium-rich foods in community dwelling elders.J Am Diet Assoc.
2002;102:1421-1427.
23.Guthrie JF,Lin B-H.Overview of the diets of lower- and higher-
income elderly and their food assistance options. J Nutr Educ Beha
2002;34(suppl):S31-S41.
24.Elbon SM, Johnson MA, Fischer JG, Searcy CA.The influence of per-
ceived milk intolerance on dairy product consumption in older adul
J Nutr Elderly. 1999;19:25-39.
25.Ajzen I.The Theory of Planned Behavior. Org Behav Hum Decis Proc
1991;50:179-211.
26.Godin G, Kok G. The Theory of Planned Behavior: a review of its
applications to health-related behaviors. Am J Health Promot. 1996
87-98.
27.Davis MA,Murphy SP,Neuhaus JM,Gee L,Quiroga SS.Living
arrangements affect dietary quality for U.S. adults aged 50 years a
older: NHANES III 1988-1994. J Nutr. 2000;130:2256-2265.
28.Backman DR, Haddad EH, Lee JW, Johnston PK, Hodgkin GE. Psy-
chosocial predictors of healthful dietary behavior in adolescents. J
Educ Behav. 2002;34:184-193.
29.Park K. Cognitive Factors Associated with the Intention and Actual
sumption of Milk among Pregnant Women [dissertation]. Columbia
University of South Carolina; 1995.
VISION, MISSION, AND GUIDING PRINCIPLES OF
THE SOCIETY FOR NUTRITION EDUCATION
Vision
Healthy people in healthy communities.
Mission
To enhance nutrition educators’ ability to promote healthful sustainable food choices and nutrition behavio
Guiding Principles
• Fiscal responsibility • Professionalism and integrity
• Respect for diversity of opinions and perspectives • Inclusiveness in membership
• Trust and willingness to communicate openly and respectfully• Equality among members
• Knowledge-based decisions • Rewarding and enjoyable experiences for
• Excellence and lifelong learning volunteers and supporters
8. Povey R, Conner M, Sparks P,James R, Shepherd R. Application of
the theory of planned behavior to two dietary behaviors: roles of per-
ceived control and self-efficacy. Br J Health Psychol. 2000;5:121-139.
9. Armitage CJ, Conner M. Efficacy of the Theory of Planned Behaviour:
a meta-analytic review. Br J Soc Psychol. 2001;40:471-499.
10.Baranowski T,Cullen K,Baranowski J.Psychosocial correlates of dietary
intake: advancing dietary intervention. Annu Rev Nutr. 1999;19:17-40.
11.Conner M, Norman P. Predicting Health Behavior: Research and Practice
with Social Cognition Models. Abingdon, Oxon, UK: Open University
Press; 1996.
12.Montano DE, Kasprzyk D,Taplin SH.The Theory of Reasoned Action
and the Theory of Planned Behavior. In: Glanz K, Lewis RM, Rimer
BK, eds.Health Behavior and Health Education.San Francisco,Calif:
Jossey-Bass; 1997:85-112.
13.Ajzen I,Madden TJ.Prediction of goal-directed behavior:attitudes,inten-
tion,and perceived behavioral control.J Exp Soc Psychol.1986;22:453-474.
14.Ureda JR. Community intervention, creating opportunities and sup-
port for cancer control behavior. Cancer. 1993;72(suppl):1125-1131.
15.Nunnally JC,Bernstein IH.Psychometric Theory.New York,NY:
McGraw-Hill; 1994.
16.Berkeley Nutrition Services. Available at:http://www.nutrition-
quest.com/.Accessed May 21, 2003.
17.Kachigan SK. Statistical Analysis:An Interdisciplinary Introduction to Uni-
variate and Multivariate Methods.New York, NY: Radius Press; 1986.
18.Melton LJ 3rd, Thamer M,Ray NF,et al.Fractures attributable to
osteoporosis:report from the National Osteoporosis Foundation.J
Bone Miner Res. 1997;12:16-23.
19.Heaney RP,Rafferty K,Dowell MS.Effect of yogurt on a urinary
marker of bone resorption in postmenopausal women.J Am Diet Assoc.
2002;102:1672-1674.
20.Lips P.Prevention of hip fractures:drug therapy.Bone.1996;18
(suppl 3):159S-163S.
21.Barr SI, McCarron DA, Heaney RP, et al. Effects of increased con-
sumption of fluid milk on energy and nutrient intake, body weight,
cardiovascular risk factors in healthy older adults.J Am Diet Assoc.
2000;100:810-817.
22.Bernstein A, Nelson ME, Tucker KL, et al. A home-based nutrition
intervention to increase consumption of fruits,vegetables,and cal-
cium-rich foods in community dwelling elders.J Am Diet Assoc.
2002;102:1421-1427.
23.Guthrie JF,Lin B-H.Overview of the diets of lower- and higher-
income elderly and their food assistance options. J Nutr Educ Beha
2002;34(suppl):S31-S41.
24.Elbon SM, Johnson MA, Fischer JG, Searcy CA.The influence of per-
ceived milk intolerance on dairy product consumption in older adul
J Nutr Elderly. 1999;19:25-39.
25.Ajzen I.The Theory of Planned Behavior. Org Behav Hum Decis Proc
1991;50:179-211.
26.Godin G, Kok G. The Theory of Planned Behavior: a review of its
applications to health-related behaviors. Am J Health Promot. 1996
87-98.
27.Davis MA,Murphy SP,Neuhaus JM,Gee L,Quiroga SS.Living
arrangements affect dietary quality for U.S. adults aged 50 years a
older: NHANES III 1988-1994. J Nutr. 2000;130:2256-2265.
28.Backman DR, Haddad EH, Lee JW, Johnston PK, Hodgkin GE. Psy-
chosocial predictors of healthful dietary behavior in adolescents. J
Educ Behav. 2002;34:184-193.
29.Park K. Cognitive Factors Associated with the Intention and Actual
sumption of Milk among Pregnant Women [dissertation]. Columbia
University of South Carolina; 1995.
VISION, MISSION, AND GUIDING PRINCIPLES OF
THE SOCIETY FOR NUTRITION EDUCATION
Vision
Healthy people in healthy communities.
Mission
To enhance nutrition educators’ ability to promote healthful sustainable food choices and nutrition behavio
Guiding Principles
• Fiscal responsibility • Professionalism and integrity
• Respect for diversity of opinions and perspectives • Inclusiveness in membership
• Trust and willingness to communicate openly and respectfully• Equality among members
• Knowledge-based decisions • Rewarding and enjoyable experiences for
• Excellence and lifelong learning volunteers and supporters
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