Fish oil supplements linked to lower risk of mortality

Regular use of fish oil supplements may be linked to a lower risk of death and cardiovascular disease (CVD) events, such as heart attack and stroke, say researchers.

Fish oil is a popular dietary supplement in the UK and other developed countries. Some evidence suggests that omega-3 fatty acids in fish oil may help prevent cardiovascular disease and reduce mortality, but conclusive evidence is still lacking.

For the findings, published in the journal the BMJ, the research team from Southern Medical University in China and Brown University in the US drew on data from the UK Biobank -- a large population based study of more than half a million British men and women.

Their analysis included 427,678 men and women aged between 40 and 69-years-old, without CVD or cancer, who were enrolled in the study from 2006 to 2010 and completed a questionnaire on supplement use, including fish oil.

According to the researchers, death certificates and hospital records were used to monitor deaths from any cause ("all-cause mortality"), CVD deaths, and CVD events, such as heart attack and stroke, through to 2018.

Almost a third (31 per cent) of participants reported taking regular fish oil supplements at the start of the study.

The researchers found that fish oil supplements were associated with a 13 per cent lower risk of all-cause mortality, a 16 per cent lower risk of CVD mortality, and a seven per cent lower risk of CVD events (388 fewer all-cause deaths, 124 fewer CVD deaths, and 295 fewer CVD events per 100,000 people in a median follow-up of nine years).

The association between fish oil use and CVD events appeared to be stronger among those with high blood pressure, the study said.

These favourable associations remained after taking account of traditional risk factors, such as age, sex, lifestyle habits, diet, medication and other supplement use.

Results were also unchanged after further analyses, suggesting that the findings withstand scrutiny.

Several mechanisms could explain these results, the researchers said.

For example, omega-3 fatty acid supplements have shown beneficial effects on blood pressure, cholesterol levels, and heart rate, all of which would exert a protective effect against the development of CVD events.

"Future studies are needed to address the extent to which the dose of fish oil supplements influences the ability to achieve a clinically meaningful effect," they added.