The extensive review of low grade bias studies by Cochrane found no evidence that long chain omega-3 supplementation (DHA/EPA) prevents or helps treat cardiovascular disease nor does it lower mortality risk. The handful of studies using oil rich fish, as a source of long chain omega-3, produced similar null effects. Although long chain omega-3 supplements did lower serum triglycerides, they were also responsible for lowering HDL cholesterol. Alpha-linolenic acid (rich in soya and rapeseed oil) did demonstrate benefits for some coronary heart disease outcomes, however, the benefits were exceptionally small. Cochrane reviewed the findings of 79 randomised controlled trials using over 110,000 subjects and focused on 25 trials of the highest design quality which followed participant for 1-6 years. The authors conclude that long chain omega-3 supplements have no impact on heart health outcomes. However, it does highlight that oil rich fish is an important source of other essential nutrients such as zinc, selenium, vitamin D and iodine; nutrients woefully lacking in the UK diet.
Clearly Cochrane's review and recommendations centre around omega 3 supplementation and not oil rich fish per se. It therefore highlights the importance of focusing on whole foods rather than supplements or single nutrients for optimum health.
Oil rich fish is not only the richest dietary source of long chain omega 3 fats EPA and DHA, but a protein source with an ideal heart healthy fat profile. Its high unsaturated and low saturated fat content makes it a perfect fit for lowering serum cholesterol levels and cardiovascular events as demonstrated by the recent SACN Saturated fat draft report [insert link to News Update SACN draft report story] and 2018 WHO draft guidelines. Additionally, it is one of the few food sources of vitamin D which has also been associated with heart health benefits. Add to this the undisputed fact that long chain omega 3 fats are critical for foetal visual and brain development and that oil rich fish is an excellent source of essential micronutrients lacking in the UK diet, consumption of this food should not be discouraged.
Current UK recommendations are for 2 140g servings of sustainably sourced fish weekly, one of which should be oil rich.
Source: Abdelhamid A, Brown T, Brainard J et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018;7:10. https://www.cochrane.org/news/new-cochrane-health-evidence-challenges-belief-omega-3-supplements-reduce-risk-heart-disease