The differential effects of EPA and DHA on cardiovascular risk factors

Omega 3 polyunsaturated fatty acids and body weight

In animal studies, n-3 PUFA have been shown to influence body composition and to reduce the accumulation of body fat, thereby affecting body weight homeostasis. In addition, it has been suggested that an additional supply of n-3 PUFA during pregnancy or lactation, or both, would have a beneficial effect on birth weight and infant growth and development. The purpose of the present study was to systematically review interventional clinical trials on the effects of dietary n-3 PUFA supplementation on body weight in adult subjects and in infants whose mothers were supplemented with these fatty acids during pregnancy and/or lactation. A systematic search, focused on n-3 PUFA and body weight, and limited to controlled clinical trials, was performed in different databases. The quality of all included studies was assessed against set criteria, and results of eligible trials were compared. There were few studies targeting this topic. In adults, all of the five studies included, except for one, show no change in body weight by dietary supplementation with n-3 PUFA. Within those trials conducted in pregnant and/or lactating women in which a main outcome was birth weight or growth in infancy, two showed a modest increase in birth weight and the rest showed no effect. None of the trials showed an effect of maternal n-3 PUFA supplementation on infant's weight at the short term. However, it should be noted that a number of limitations, including a variety of experimental designs, type and doses of n-3 PUFA, and high attrition rates, among others, make impossible to draw robust conclusions from this review.

DHA derivatives of fish oil as dietary supplements: a nutrition-based drug discovery approach for therapies to prevent metabolic cardiotoxicity

INTRODUCTION

During the early 1970s, Danish physicians Jorn Dyerberg and colleagues observed that Greenland Eskimos consuming fatty fishes exhibited low incidences of heart disease. Fish oil is now one of the most commonly consumed dietary supplements. In 2004, concentrated fish oil was approved as a drug by the FDA for the treatment of hyperlipidemia. Fish oil contains two major omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). With advancements in lipid concentration and purification techniques, EPA- or DHA-enriched products are now commercially available, and the availability of these components in isolation allows their individual effects to be examined. Newly synthesized derivatives and endogenously discovered metabolites of DHA exhibit therapeutic utility for obesity, metabolic syndrome and cardiovascular disease.

AREAS COVERED

This review summarizes our current knowledge on the distinct effects of EPA and DHA to prevent metabolic syndrome and reduce cardiotoxicity risk. Since EPA is an integral component of fish oil, we will briefly review EPA effects, but our main theme will be to summarize effects of the DHA derivatives that are available today. We focus on using nutrition-based drug discovery to explore the potential of DHA derivatives for the treatment of obesity, metabolic syndrome and cardiovascular diseases.

EXPERT OPINION

The safety and efficacy evaluation of DHA derivatives will provide novel biomolecules for the drug discovery arsenal. Novel nutritional-based drug discoveries of DHA derivatives or metabolites may provide realistic and alternative strategies for the treatment of metabolic and cardiovascular disease.

High-glycemic index carbohydrates abrogate the antiobesity effect of fish oil in mice

Fish oil rich in n-3 polyunsaturated fatty acids is known to attenuate diet-induced obesity and adipose tissue inflammation in rodents. Here we aimed to investigate whether different carbohydrate sources modulated the antiobesity effects of fish oil. By feeding C57BL/6J mice isocaloric high-fat diets enriched with fish oil for 6 wk, we show that increasing amounts of sucrose in the diets dose-dependently increased energy efficiency and white adipose tissue (WAT) mass. Mice receiving fructose had about 50% less WAT mass than mice fed a high fish oil diet supplemented with either glucose or sucrose, indicating that the glucose moiety of sucrose was responsible for the obesity-promoting effect of sucrose. To investigate whether the obesogenic effect of sucrose and glucose was related to stimulation of insulin secretion, we combined fish oil with high and low glycemic index (GI) starches. Mice receiving the fish oil diet containing the low-GI starch had significantly less WAT than mice fed high-GI starch. Moreover, inhibition of insulin secretion by administration of nifedipine significantly reduced WAT mass in mice fed a high-fish oil diet in combination with sucrose. Our data show that the macronutrient composition of the diet modulates the effects of fish oil. Fish oil combined with sucrose, glucose, or high-GI starch promotes obesity, and the reported anti-inflammatory actions of fish oil are abrogated. In conclusion, our data indicate that glycemic control of insulin secretion modulates metabolic effects of fish oil by demonstrating that high-GI carbohydrates attenuate the antiobesity effects of fish oil.

Similarities and differences between the effects of EPA and DHA on markers of atherosclerosis in human subjects

We have reviewed effects of long chain (LC) n-3 PUFA on markers of atherosclerosis in human subjects with a focus on individual effects of EPA and DHA. Initial results from epidemiological studies suggested that LC n-3 PUFA from fish oils (FO) reduced incidence of CVD; those results have been confirmed in interventional studies. Dietary intervention with n-3 PUFA decreased fasting and postprandial TAG, number of remnant-like chylomicron particles, large VLDL, and total and small dense LDL particles. It increased mean size of LDL particles by increasing number of large and decreasing those of small dense particles. With some exceptions, n-3 PUFA decreased blood pressure (BP) and heart rate (HR), flow-mediated dilation (FMD) and plasma concentrations of inflammatory markers. n-3 PUFA also decreased circulating adhesion molecules and intima-media thickness (IMT) in some but not other studies. For IMT, results varied with the sex and artery being examined. EPA effects on FMD are endothelial cell dependent, while those of DHA seem to be endothelial cell independent. Individually, both EPA and DHA decreased TAG and inflammatory markers, but only DHA decreased HR, BP and number of small dense LDL particles. Results varied because of dose and duration of n-3 PUFA, EPA:DHA, health status of subjects and other reasons. Future studies are needed to determine optimal doses of EPA and DHA individually, their synergistic, additive or antagonistic effects, and to understand underlying mechanisms. In conclusion, n-3 PUFA decreased several risk factors for atherosclerosis without any serious adverse effects.

Novel developments in omega-3 fatty acid-based strategies

PURPOSE OF REVIEW

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been attributed with several health benefits, including triglyceride lowering and cardiovascular disease risk reduction. This review focuses on new prescription omega-3 fatty acid products in development and recently published data regarding omega-3 fatty acid effects on arrhythmias, heart failure, and platelet inactivation.

RECENT FINDINGS

A free fatty acid form of n-3 PUFA was found to produce a four-fold higher area under the plasma n-3 PUFA curve than prescription omega-3-acid ethyl esters in patients on a low-fat diet. Eicosapentaenoic acid ethyl esters reduced triglyceride without significantly elevating LDL cholesterol in patients with severe hypertriglyceridemia and in those with mixed dyslipidemia. Recent investigations of n-3 PUFA effects on ventricular and atrial arrhythmias, including studies in patients with implanted defibrillators, failed to demonstrate a significant benefit. However, increased fatty fish or n-3 PUFA consumption was associated with a lower rate of hospitalization in heart failure patients. A further important finding was potentiation of the antiplatelet response when n-3 PUFAs were added to aspirin + clopidogrel.

SUMMARY

Although n-3 PUFA therapy continues to show promise in the prevention and management of cardiovascular diseases, further research is necessary to more fully elucidate its role in specific disorders.