Effects of (n-3) polyunsaturated fatty acids on cardiovascular health

By Maleeha Saleem ( BS Biochemistry)

Effects of (n-3) polyunsaturated fatty acids on cardiovascular health

Abstract

Omega 3 polyunsaturated fatty acids are beneficial to prevent cardiovascular diseases such as coronary heart disease, atherosclerosis, arrhythmias, and heart failure. Dietary sources rich in omega 3 PUFAs (EPA+DHA) include fish oils. The EPA+DHA consumption should be at least 500 mg/day for individuals without underlying overt CV disease and at least 800 to 1,000 mg/day for individuals with known coronary heart disease and HF.

Introduction

The role of (n-3) polyunsaturated fatty acids in cardiovascular health had been studied for decades. In 1944, it was reported that consuming a diet rich in (n-3) PUFAs, reduced the risk of coronary heart disease. These fatty acids are also called omega 3 PUFAs because of containing the first site of unsaturation after third carbon from the omega end, also known as methyl end. α- linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are three types of omega 3 PUFAs. The most important ω-3 PUFAs are EPA and DHA. Dietary sources of EPA and DHA include fish oils. EPA and DHA can also be synthesized from α-linolenic acid. Nowadays, there is growing evidence showing that omega 3 PUFAs have many heart _healthy properties like the reduction of arrhythmias, coronary heart disease, atherosclerosis, and heart failure. Randomized controlled trials indicate that consumption of (n-3) PUFA at 10–21 % energy reduces the risk of CVD by 17 %. The purpose of this review article is to show the effects of (n-3) PUFAs on CV health, explain major benefits and uses of (n-3)PUFAs and make recommendations for future research.

Role in Prevention of CV diseases

1-Coronary heart disease (CHD)

Intake of a diet rich in omega 3 PUFAs is effective in primary and especially in secondary prevention of CHD.CHD is the blockage of blood supply through coronary arteries to the heart muscle due to the deposition of fatty materials like cholesterol. The function of omega 3 PUFAs is actually to lower the LDL (cholesterol) level so the consumption of omega 3 PUFAs reduces the risk of CHD. Two types of (n-3) PUFAs like EPA and DHA show more contributions to prevent CHD than ALA. The intake of EPA (1.8 g/day) reduces the incidence of major adverse coronary events by 19%.In a randomized trial, intake of omega 3 PUFAs, either in the form of oily fish or fish oil capsules reduced 2-year all-cause mortality by 29% which is entirely attributable to a reduction in CHD mortality.

2-Atherosclerosis

The very high intake of marine-derived omega-3 PUFA has anti_ atherosclerotic effects. Atherosclerosis is the hardening of the arteries due to the build_ up of fat (cholesterol) and calcium in the artery wall, forming a substance called plaque. The role of omega 3 PUFAs is to reduce the risk of hypercholesterolemia so the intake of omega 3 PUFAs is effective to prevent atherosclerosis. It is evident from studies that intima-media thickness (IMT) and coronary artery calcification (CAC), both independent predictors of CV events, the Japanese have a lower level of atherosclerosis than the Caucasians residing in the U.S because the former consume more omega 3 PUFAs than latter.

3-Arrhythmias

The diet rich in omega 3 PUFAs is antiarrhythmic. Arrhythmias are irregular heartbeats, also called dysrhythmias, which occur due to the electrolyte imbalances in the blood (such as sodium or potassium), CHD, and changes in the heart muscle. Omega 3 PUFAs are effective to prevent arrhythmias due to their ability to inhibit fast, voltage-dependent sodium channels and L-type calcium channels. DHA directly inhibits the delayed rectifier potassium channel which is involved in the depolarization phase of ventricular and atrial cardiac potentials. So DHA causes atrial and ventricular repolarization providing greater protection against dysrhythmias. In studies, it has been shown that patients with impaired systolic function show improvements in heart rate variability after 4.3 g/day of EPA and DHA for 12 weeks. Moreover, it has been shown that the consumption of high quantities of nonfried fish reduces the 30 percent risk of AF (Atrial fibrillation).                    

4-Heart failure

The dietary fish (unfried) and fish oil containing omega 3 PUFAs are beneficial to prevent heart failure. HF is a term that refers to a heart that cannot keep up with its workload so the body is not supplied with oxygen properly it needs. HF occurs due to many forms of heart diseases like coronary heart disease, heart defects, heart infections, or cardiomyopathy. Diet rich in omega 3 PUFAs prevents coronary heart disease so prevents heart failure. It has been estimated that intake of one capsule daily of a concentrated fish oil Lovaza, containing approx..850 mg of EPA plus DHA reduces the total mortality by 8%.          

Sources of omega 3 PUFAs

Name	Sources
α-linolenic acid	Selected vegetable oil       (flaxseed, canola)
EPA	Marine oils and fish
DHA	Marine oils and fish

Fish content of EPA and DHA

Name	EPA       (g/100g)	DHA        (g/100g)
Bluefin	0.363	1.141
Atlantic, farmed	0.690	1.457
Chinook	1.010	0.727

Recommended doses

The EPA +DHA consumption should be at least 500 mg/day for individuals who are not underlying CV diseases while at least 800-1000 mg /day for individuals having coronary heart disease and heart failure.

Complications

Although a diet rich in omega 3 PUFAs is beneficial for human health but too much consumption of omega 3 PUFAs has side effects. Omacor is an omega-3 fatty acid formulation with high concentrations of EPA (465 mg) and DHA (375 mg) in each 1-g capsule, increases modestly plasma levels of low-density lipoprotein if consumed in excess.

Conclusion             .

Although most of the deaths in the world occur due to cardiovascular diseases.CV diseases can be treated by consuming a diet rich in omega 3 PUFAs containing 800-1000 mg EPA+DHA. The unfried fish is the rich source of omega 3 PUFAs. So the death rate of the world can be reduced by consuming a diet rich in omega 3 PUFAs.

References

Elagizi, A., Lavie, C. J., Marshall, K., DiNicolantonio, J. J., O'Keefe, J. H., &Milani, R. V. (2018). Omega-3 polyunsaturated fatty acids and cardiovascular health: a comprehensive review. Progress in cardiovascular diseases, 61(1), 76-85.

Tortosa-Caparrós, E., Navas-Carrillo, D., Marín, F., &Orenes-Piñero, E. (2017). Anti-inflammatory effects of omega 3 and omega 6 polyunsaturated fatty acids in cardiovascular disease and metabolic syndrome. Critical reviews in food science and nutrition, 57(16), 3421-3429.

Kris-Etherton, P. M., Hecker, K. D., &Binkoski, A. E. (2004). Polyunsaturated fatty acids and cardiovascular health. Nutrition Reviews, 62(11), 414-426.

Lavie, C. J., O'Keefe, J. H., Milani, R. V., Ventura, H. O., &Mehra, M. R. (2009). New data on the clinical impact of exercise training, fish oils, and statins in heart failure. The Physician and Sportsmedicine, 37(2), 22-28.

Bays, H. (2006). Clinical overview of Omacor: a concentrated formulation of omega-3 polyunsaturated fatty acids. The American journal of cardiology, 98(4), 71-76.

Author's Details

Maleeha Saleem

BS (Hons.)

Department of Biochemistry, GC University, Faisalabad.

Reviewed & Edited by

M.Ahsan ul haq

M.Phil Scholar

Department of Biochemistry, GC University, Faisalabad.