An extensive detailed analysis of the current scientific evidence into omega-3 seems to have thrown a spanner in the works for heart health dietary advice.
Conducted by Cochrane, the review concludes that there is no correlation between cardiovascular health and intakes of the long chain omega-3 fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) over a one- to six-year period.
Long chain omega-3 fats have long been associated with reductions in blood triglycerides, blood pressure and thrombosis; producing anti-inflammatory and anti-arrhythmia effects as well as improving endothelial function and insulin sensitivity.
This most recent publication will raise many eyebrows within the heart health professional arena and likely to be taken up by media editors who seem to enjoy questioning the trustworthiness of public health guidelines. These recommend a diet including omega-3, especially found in oil-rich fish such as salmon, tuna and mackerel.
So, do we need to change dietary guidelines on the importance of omega-3 and oil-rich fish?
Before we jump the gun, it’s important to put things into context:
1. The shortcomings of the review
a. The studies investigated in this review predominantly used omega-3 supplements. Thus the outcomes cannot be related to oil-rich fish consumption which is the main dietary source of EPA and DHA.
b. The studies were also of one to six years’ duration, which is a relatively short period to assess disease and mortality risk. And conclusions cannot be reached for a lifetime consumption of foods rich in EPA or DHA.
c. Many of the studies may not have used adequate number pf subjects in the studies to elicit a result. This is especially the case for studies conducted in healthy individuals (and therefore low risk of heart disease), which would require very high numbers to demonstrate a difference in the omega-3 and non-omega-3 study groups.
d. Any studies conducted over the last two decades of people at risk of cardiovascular disease (CVD) will be in individuals already medicated with statins and other cardio-protective drugs, which may mask the effect, if any, of additional omega-3.
2. Omega-3 benefits go beyond heart health
Long chain omega-3 fats are critical for eye and brain development of the foetus and young children. Therefore, food sources should be included in a healthy balanced diet of children and adults planning for a family.
3. Oil-rich fish is not just omega-3. It offers so many health benefits.
a. Unlike omega-3 supplements, oil-rich fish is a rich source of not only the long chain omega-3 fats but also of selenium, zinc, vitamin D and iodine; woefully lacking in the UK diet.
b. Oil-rich fish has a healthier fat profile when compared to red meat and other animal proteins. Replacing saturated fat with unsaturated fat in the diet has been proven to have a positive effect on blood lipids and cardiovascular health (as confirmed by Cochrane’s 2015 review and the SACN’s & the WHO’s draft 2018 reports). See our saturated fat blog
Indeed, the authors themselves remind us of the other nutritional benefits of oil-rich fish and that this review does not negate public health advice that consuming oil-rich fish is beneficial to health.
The Nutrilicious view
Taking vitamin and mineral supplements as a substitute for eating a healthy balanced diet has never been encouraged by health professionals. However, dietitians recognise that when demands for specific nutrients are high, or when an individual’s nutritional intake is at proven risk of being compromised, supplements can play an important role. For example, pregnancy and folic acid; under-5 year olds and vitamins C and D; or sufferers of osteoporosis and calcium and vitamin D.
Therefore, these findings do not come as any surprise: omega-3 supplements are not a solution to better heart health. There are numerous dietary and lifestyle factors that impact on heart health. It should always be about food rather than the benefits of single nutrients.
As Linda Main, Dietitian and dietary advisor for cholesterol charity HEART UK, explains: “We continue to advise the lifelong consumption of a heart healthy diet centred around eating whole foods rather than the emphasis being on nutrients.
“Eating patterns such as the Mediterranean, DASH or the UCLP© diets result in the consumption of a nutritionally appropriate diet. This is characterised by eating plenty of vegetables, fruits, wholegrains, vegetable proteins such as nuts and soya, seeds, vegetable oils and spreads. In those who consume animal proteins, the inclusion of low fat dairy, lean and largely unprocessed meat and white and oily fish and seafood are recommended.
“Omega-3 supplements are not currently advised by HEART UK and would not be our first choice, except when prescribed by a recognised qualified health professional or when needed to safeguard the intake of the essentially fatty acid – alpha-linolenic acid.”
As oil-rich fish is an excellent low saturated fat protein source, and the main dietary source of long-chain omega-3 fats as well as other crucial nutrients, it should continue to be part of dietary guidelines.
Additionally, for those wishing to follow a more plant-based diet, it’s reassuring that the report finds consumption of the shorter chain omega-3 fats found in plant foods (like rapeseed and soya oil) has cardio-protective qualities. This supports findings from population studies that vegetarians and vegans have a lower incidence of cardiovascular events and mortality compared to non-vegetarians.
Current UK heart health dietary advice remains unchanged:
- Lower the amount of food eaten which is high in saturated fat and replace it with foods high in unsaturated fats (which Cochrane’s 2015 review supports, SACN 2017 Saturated fat draft guidance).
- Increase our intake of fibre (especially from beans, pulses, oats and barley), nuts.
- Consume at least five servings of fruit and vegetables daily.
- Reduce intakes of red meat and avoid/limit processed meat.
- Consume two portions of fish weekly – one of which should be oil rich.
- Increase intakes of leaner and plant-sources of protein.
- Use sterol or stanol fortified products (if blood cholesterol is raised after other dietary changes have been made).
It’s interesting to note that, unlike the US, the UK does not (and has never) recommended taking dietary supplements of omega-3 fish oil.
For up to date expert advice on heart health visit: heartuk.org.uk
Saturated fat and heart health reports
- 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.
- Hooper L, Martin N, Abdelhamid A et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rv. 2015;(Issue 6):Art. No.: CD011737.
Vegetarian and vegan diets and health outcomes
- Rizzo N, Jaceldo-Siegl K, Sabate J et al. Nutrient profiles of vegetarian and non-vegetarian dietary patterns. J Acad Nutr Diet.. 2013;113(12):1610-9.
- Sobiecki J, Appleby P, Bradbury K et al. High compliance with dietary recommendations in a cohort of meat eaters, fish eaters, vegetarians, and vegans: results from the European Prospective Investigation into Cancer and Nutrition-Oxford study. Nutr Res.. 2016;36(5):464-77.
- Springmann M, Godfray H, Rayner M et al. Analysis and valuation of the health and climate change cobenefits of dietary change. Proc Natl Acad Sci U S A.. 2016;113(15):4146-51.
- Clarys P, Deliens T, Huybrechts I et al. Comparison of nutritional quality of the vegan, vegetarian, semi-vegetarian, pesco-vegetarian and omnivorous diet. Nutrients.. 2014;6(3):1318-32.
Cochrane is an established body of researchers, health professionals and patients across the globe renowned for their high quality scientific reviews of nutrition and health evidence.