New evidence just released suggests that Omega-3 supplements have little effect in reducing the risk of heart disease, stroke and death.
Omega-3 is an unsaturated fatty acid commonly found in deep-sea fish and certain plants and is very beneficial to human health. The main types of Omega-3 include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is usually found in the fat of plant foods such as nuts and seeds (walnuts and rapeseed are rich in ALA). EPA and DHA are known as long-chain Omega-3 fatty acids, which are found in fish fats such as salmon and cod liver oil.
Omega-3 fatty acids are becoming more widely available worldwide. Because it is widely believed that Omega-3 fatty acids can prevent heart disease, and more than one mechanism can help prevent heart disease, including lowering blood pressure or cholesterol. Omega-3 fatty acids are widely purchased and used by consumers because they are a very easy to buy supplement.
A new Cochrane systematic review published on The Cochrane database of systematic reviews on July 18, 2018 combined the results of 79 randomized trials involving 112,059 people. These studies evaluated the effects of additional Omega-3 fat on heart and circulatory diseases compared to normal or lower Omega-3. Of these, 25 studies were considered highly credible because of their good design and implementation.
The subjects enrolled in these studies ranged from male to female, including both healthy and sick patients. They are from North America, Europe, Australia, and Asia and are randomized to either increase Omega-3 fatty acid intake or maintain normal levels. The study lasted for at least a year. Most studies have investigated the effects of long-chain Omega-3 fatty acid supplements in capsule form and compared them to placebo. Only a few studies have assessed overall fish intake. Most ALA tests add Omega-3 fatty acids to foods such as margarine, and give these groups an ALA-rich food or a food that is naturally rich in ALA (such as walnuts), The control group consumed ordinary food.
Cochrane researchers found that increasing the intake of long-chain Omega-3 fatty acids had little benefit to the health indicators they analyzed. They found highly positive evidence that long-chain Omega-3 fatty acids have little or no meaningful impact on the risk of any form of death. Subjects in the experimental group taking long-chain Omega-3 fatty acids had a all-cause mortality rate of 8.8%, compared with 9% in the control group.
They also found that taking more long-chain Omega-3 fatty acids (including EPA and DHA) through supplementation had little effect in reducing the risk of cardiovascular disease, coronary heart disease, stroke or cardiac dysfunction. Long-chain Omega-3 fatty acids may indeed reduce some of the blood lipids, triglycerides and high-density lipoprotein (HDL) cholesterol. Lowering triglycerides may have a protective effect on the heart, but lowering HDL cholesterol has the opposite effect. The researchers collected information about the hazards in these studies, but information about bleeding and thrombosis is very limited.
This systematic review suggests that intake of more ALA through food or supplements may have no effect on cardiovascular deaths and other causes of death. However, intake of more ALA can reduce the risk of cardiac dysfunction from 3.3% to 2.6%. The team found that taking ALA had a very small effect on reducing cardiovascular risk, so that only about one in 1,000 people who increased their ALA intake would benefit. Similar results for cardiovascular risk of death. They did not find enough data in these studies to assess the effect of taking ALA on the risk of bleeding or thrombosis.
Increasing the intake of long-chain Omega-3 fatty acids or ALA may have no effect on body weight or obesity.