Cod liver oil and omega three does NOT prevent diabetes, Norwich study finds

Stock photo of a girl taking cod liver oil. Photo: PA

Stock photo of a girl taking cod liver oil. Photo: PA - Credit: PA

Fish oil supplements have little to no impact on preventing type two diabetes and in some cases can even make things worse, researchers in Norwich have discovered.

A study by researchers at the Norwich Medical School, based at the University of East Anglia, looked into the perceived benefits of omega three fats, which are widely promoted globally because of a common belief that it will protect against, or even reverse, conditions such as diabetes.

But the World Health Organisation commissioned trial, which had more than 58,000 participants, found those who were having more fish oil had the same risk of diabetes diagnosis as the control group who did not.

There was no effect on blood glusocse, insulin, or glycated haemoglobin levels, which are important measures of diabetes risk.

However, there was some evidence that when people take high doses of fish oils they may experience worsening glucose metabolism.

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As well as finding omega three in nuts and seeds, and fatty fish such as salmon, many people take cod liver oil available over the counter.

Lead author Dr Lee Hooper, from UEA's Norwich Medical School, said: "Our previous research has shown that long-chain omega three supplements, including fish oils, do not protect against conditions such as heart disease, stroke or death. This review shows that they do not prevent or treat diabetes either.

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"Omega three supplements should not be encouraged for diabetes prevention or treatment. If people do choose to take supplementary fish oil capsules to treat or prevent diabetes, or to reduce levels of triglycerides in their blood, then they should use doses of less than 4.4 grams per day to avoid possible negative outcomes.

"This large systematic review included information from many thousands of people over long periods. Despite all this information, we don't see protective effects.

"The most trustworthy studies consistently showed little or no effect of long-chain omega three fats on diabetes."

Joint first author, Dr Julii Brainard also from Norwich Medical School, said: "Oily fish can be a very nutritious food as part of a balanced diet, but we did not find enough trials that encouraged participants to eat more oily fish to know whether it is useful in preventing diabetes or improving glucose metabolism."

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