Effect of Omega-3 Fatty Acids on Cardiovascular Diseases

Abstract
Previous investigations have exposed the benefits of using omega-3 polyunsaturated fatty acid
(PUFA) for treatment of cardiovascular diseases (CVD). Findings different types of research
have shown, omega-3 PUFAs lessened the overall impermanence and therefore, used to
recommend intake of omega-3 PUFA for CVD patients in early 2000s. However, current studies
from researches have demonstrated inconsistent result for benefits of omega-3 PUFA intake
among people with CVD. Reason for the inconsistent findings were proposed as concise
treatment interval, comparatively low dose of omega-3 PUFAs, small size of samples, more
quantity of background consumption of omega-3, and the simultaneous usage of
pharmacological interventions for improving CVD outcomes. The aim of the review, present the
summary of current evidence about the effect of omega-3 fatty acids on organization of CVDs.
Many studies are reviewed the answer to research question. On reviewing current literature, it is
found that studies have demonstrated conflicting outcomes. Findings of the study along with
their methodology and limitations are discussed in order to understand the inconsistency in the
outcomes of these researches about valuable impact of omega-3 PUFA on people with CVD.
Further long-standing research of omega-3 fatty acid usage is required for establishing if they are
beneficial for CVD outcomes.
Pathophysiology of the cardiovascular disease and omega-
3 intake
CVD is the chief cause of mortality across the globe, causing an estimated 17.3 million deaths
annually. It is expected that this figure will rise to over 23.6 million by 2030 [1]. The structure of
unsaturated fats incorporates hydrocarbon chain having carboxyl gathering and a methyl bunch
at inverse sides [2]. An immersed unsaturated fat does not have a twofold security in the
hydrocarbon chain while the unsaturated fat has single and various twofold securities inside
hydrocarbon chain as shown in Fig. 1. Unsaturated fats are subdivided as monounsaturated
unsaturated fats which have single twofold security and PUFAs that has more than two or two
twofold securities. Omega-3 and omega-6 unsaturated fats are ordered by PUFAs. In the omega-
3 unsaturated fats, the main twofold security is available between the third and fourth carbons
from the methyl end and is gathered as long chain unsaturated fats in light of the length of the
carbon chain. α-linoleic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid
(DHA) are the three omega-3 PUFAs which have exceptional criticalness in human nourishment.

Fig. 1 Types of fatty acids
Omega-3 PUFAs is a group of nutrients found to have positive impact on human health. The
useful effect of omega-3 PUFA has been studied in detail with reference to an array of illnesses
which includes CVD as well. Like, a study evaluated the physiological influence of marine-
derived omega-3 PUFAs on the cardiovascular status and outcomes [3]. Study establishes that
omega-3 PUFAs lower triglycerides, blood pressure, and resting heart rate. In addition, it also
improved endothelial dysfunction in clinical settings. Proof from the writing demonstrates that
separated from the above advantages, omega-3 PUFAs can likewise bring down the foundational
vascular opposition and arrhythmias and improve myocardial effectiveness and left ventricular
diastolic filling. At exceptionally high dosages omega-3 PUFAs have additionally indicated
antithrombotic impacts. Besides, omega-3 metabolites of PUFA have calming properties.
A range of appliances have been put forward to describe the positive possessions of omega-3
PUFAs on cardiovascular outcomes. Some of those mechanisms include prevention of
arrhythmias, reduction of plasma triacylglycerol, lowering of blood pressure, reduction in
platelet aggregation, reduction in arterial cholesterol transfer, improvement in vascular
relaxation, reduction in arterial inflammatory responses, and surge in heart rate variability [4]. It
is chiefly recognized that the omega-3 PUFAs decrease the serum ranks of triglycerides. They
perform this partially by reducing the combination, very low-density lipoprotein in liver and
partially by increasing the breakdown of fatty acids and quickening the clearance of triglyceride
by the plasma [5]. Some research has revealed effect of omega-3 PUFAs on improvement of
flow-mediated arterial dilation and mechanical functioning of heart [6]. Foods which are ironic
in omega-3 PUFAs had protective effect alongside coronary artery atherosclerosis in nonhuman
primates. This upshot seemed toward independent on the lipoproteins plasma level. Omega-3
PUFAs have demonstrated cardioprotective impact both in prime and secondary coronary heart
disease (CHD) prevention trials conducted on human. However, many studies also failed to
establish this suggestion between the omega-3 PUFAs and CVD. The inconsistent findings
among many studies have led to the argument or confusion regarding association between
omega-3 PUFAs and CVD outcomes. The review will summarize scientific proof from all the
relevant research studies to find out whether omega-3 PUFAs have cardioprotective effect or not.
The review will also attempt to present the reasoning for inconsistent findings.
Findings from the nutrition literature along with critical evaluation

Review searched for the studies conducted in last 10 years to answer the research question. The
double blind, double blind randomized controlled trial (RCT) conducted on 633 patients who
consumed 600 mg omega-3 supplement daily for an average time interval of 4.7 years revealed
that there was no substantial reduction in chief cardiovascular events which included
cardiovascular mortality [7]. The study nulled the cardioprotective outcome of omega-3 PUFAs.
The findings of this RCT were supported by another randomized double-blind placebo-
controlled trial which was conducted on 1192 patients for the time period of 40 months The
examination found that when a gauge of 226 mg EPA and 150 mg DHA was enhanced day by
day, it doesn't bring down the rate of major cardiovascular occasions significantly [8]. Another
randomized, double blind placebo-controlled trial, called OMEGA was conducted to investigate,
impact of highly purified omega-3 fatty acids along with the guideline-regulated intervention
after myocardial infarction (MI) among 1925 patients. OMEGA revealed that there was none
further protection against sudden cardiac death and other cardiovascular events. The research
assessed the patients who were delivered guideline-regulated action of acute MI along with1
gram omega-3 daily for 12 months [9]. However, OMEGA had limitations of smaller sample
size and inadequate follow-up time period.
One of the extreme outcomes of the CVD is heart failure. With respect to heart failure,
randomized double-blind placebo-controlled trial conducted on 3494 patients who had one gram
supplementation of omega-3 for an average period of 3.9 years demonstrated a slight reduction
in the likelihood of mortality due to cardiovascular reasons. The RCT also found slight reduction
in hospital admissions because of cardiovascular events [10]. However, in spite of a elegant
RCT, examine endpoints achieved measurably critical contrasts over the arms simply after
change for uneven characters in benchmark qualities
Furthermore, electrophysiological impacts of omega-3 fatty acids on animal myocytes indicate
the anti- arrhythmic effects which can be present in them, however trial conducted on humans on
arrhythmia demonstrated inconsistent outcomes. Several clinical trials attempted to ascertain the
clinical efficacy of these electrophysiological effects. A trail including 205 patients of atrial
fibrillation (AF) found that when the patients were supplemented by an amount of 2 grams
omega-3 per day for one year period, it assisted them in upholding rhythm after direct current
cardioversion. The findings of this study were contrasted by other two trials. A trial which
included 586 patients of AF found that when the patients were supplemented with a dose of 1
gram omega-3 per day for over a year, no reduction occurred in the recurrent AF [11]. Another
trail which included 546 patients of implantable cardioverter defibrillators alongside history of
harmful ventricular tachycardia or ventricular fibrillation who were given supplementation with
2 grams omega-3 for over a year found no decrease in tachyarrhythmia [12]. No pure primary
prevention trials were found which examined the effect of omega-3 supplementation on hard
endpoints. But a trial which involved 328 healthy individuals between the age of 18 and 37 years
were given 1.6 grams of DHA supplement for a period of 4 months. The trial demonstrated that
in spite of minor positions of serum triglycerides and extremely low-thickness lipoprotein, no
improvement occurred in endothelial capacity.
It can be said that findings of several RCTs were mixed as some established the cardiovascular
benefits of omega-3 while other RCTs negated the cardioprotective effect. A systematic review
included all the randomized trials conducted between 1989 and 2012 which investigated the
cardiovascular effects of omega-3 among adults [13]. The review comprised of 20 studies which
accounted for 68,680 randomized patients. The average follow-up period for the studies was 2