Omega-3 fats: What they cannot do for health

Omega-3 fatty acids have been successfully marketed as heart-friendly and reported to reduce the risk of adverse heart disease-related outcomes.

However, its role and health benefits for some conditions have been challenged and discredited. This Cochrane report review found no evidence of the benefit of omega-3 supplements on heart disease, stroke, or death.

Here are some conditions that omega-3 fatty acids may not prevent or improve, based on the latest scientific evidence.

Reduce risk of death by heart disease

Prof. Shahidi and Prof. Ambigaipalan also found that the consumption of omega-3 fatty acids does not reduce the risk of adverse heart disease-related outcomes, such as sudden cardiac death, heart attack, or stroke, even in individuals without a history of disease.

Although omega-3 fats lower the risk of developing heart disease by lowering triglyceride, the “bad” cholesterol LDL, and blood pressure, a meta-analysis of over 80,000 individuals found that their supplementation neither prevented death from all causes nor heart disease.

Prevent blood clots

Anti-clotting effects of omega-3 fatty acids have been proposed by reducing platelet aggregation. However, this finding has been controversial, and the evidence in this regard is weak — typical doses of omega-3 fats from foods and supplements have a mild effect.

Prevent or treat diabetes

Evidence suggests that increasing omega-3 intake does not prevent or treat diabetes.

It does not affect fasting blood sugar, insulin resistance, or glycosylated hemoglobin in those with type 2 diabetes and metabolic syndrome.

Prevent cancer

Omega-3 fatty acids have been reported to reduce the complications of some cancer patients, and early findings look promising. However, there is no evidence of any action of omega-3s preventing the development of cancers.

In a meta-analysis of over one million people, a particularly high intake of omega-3 fats — 5–15 g per day — did not significantly reduce lung cancer risk, and in some cases, increased the risk of developing lung cancer.

Therefore, too low or too high omega-3 intake may be harmful.

The bottom line

Omega-3 polyunsaturated fatty acids are essential compounds that are key building blocks for cell membranes, particularly in the brain.

For decades, they have been the subject of scientific interest, but findings have been controversial and inconsistent.

The evidence shows that omega-3 fatty acids have anti-inflammatory properties and may lower cholesterol, blood pressure, depressive episodes, weight loss during cancer treatment, and the risk for heart disease.

However, omega-3 intake does not reduce the risk of adverse and severe heart disease-related outcomes, including sudden death and stroke. Additionally, it cannot prevent or treat diabetes or prevent blood clots.

This is an emerging area of evidence, and further results will continue to inform health recommendations.