Researchers have concluded that omega-3 fatty acids in fish oil have little or no effect on the risk of developing Type 2 diabetes.

“Increased consumption of omega-3 fats is widely promoted globally because of a common belief that it will protect against, or even reverse, conditions such as diabetes,” the UK University of East Anglia (UEA) said on 21 August.

However, a systematic review, commissioned by the World Health Organization (WHO) and conducted by UEA researchers, found that omega-3 supplements offered no health benefit.

The review looked at the results of 83 studies published from the 1960s to 2018 involving 121,070 participants with and without diabetes, all with at least six-month duration.

“Despite over 58,000 participants being randomised into long-term trials, and 4% of them developing diabetes, those who were randomised to consume more long-chain omega-3 fats (fish oils) had the same risk of diabetes diagnosis as the control group who did not take more fish oil,” the UEA stated.

The university said there was a consistent lack of effect of fish oils on the factors related to diabetes risk.

“Our previous research has also shown that long-chain omega-3 supplements, including fish oils, do not protect against conditions such as heart disease, stroke or death,” said lead author Dr Lee Hooper, from UEA’s Norwich Medical School.

However, she noted that fish oil supplements could help reduce high levels of triglycerides, a type of blood fat that contributed to heart disease.

Hooper added that if people did take omega-3 supplements, the dose should be no more than 4.4g/day to avoid negative effects.

The main types of omega-3 fatty acids are alphalinolenic acid (ALA), docosahexaenoic acid and (DHA) eicosapentaenoic acid (EPA).

EPA and DHA, collectively called long-chain omega-3 fats, were naturally found in fatty fish, such as salmon.

ALA was found in fats from plant foods such as nuts and seeds.

The research team also assessed the effects of ALA, omega-6 and polyunsaturated fatty acids (PUFA) – taken as supplementary capsules, or via enriched or naturally rich foods.

However there was insufficient data from these trials to determine whether they had protective or harmful effects, the statement said.