A high dietary intake of alpha linolenic acid (ALA) is associated with a lower risk of death from all causes and from cardiovascular disease and coronary heart disease, a study has found.

Previous research had shown a high intake of ALA, a type of omega 3 fatty acid found in nuts, seeds and plant oils, was associated with a lower risk of fatal coronary heart disease, but other studies have been inconclusive.

In a systematic review and meta-analysis, a team of international researchers looked at 41 prospective cohort studies published between 1991 and 2021 on the associations between ALA and risk of death from all causes, cardiovascular and cancer mortality.

The studies included a total of 1,197,564 participants who were followed for between two and 32 years, researchers wrote in the BMJ.

After assessing studies for bias, they found a higher intake of ALA was associated with a 10% lower risk of death from all causes, an 8% lower risk of cardiovascular disease death and an 11% lower risk of coronary heart disease death.

‘A higher intake of ALA, however, was associated with a slightly higher risk of cancer mortality,’ the researchers wrote. 

A dose-response effect was found for cardiovascular disease mortality, with each 1g/day increase in ALA intake (equivalent to one tablespoon of canola oil) associated with a 5% lower risk of cardiovascular disease death.

Researchers also found that higher blood levels of ALA were associated with lower risk of all-cause mortality. Further analysis found each one standard deviation increment in blood concentrations of ALA was associated with an 8% lower risk of coronary heart disease mortality.

‘Further studies should examine the association between ALA and a wider range of causes of death to provide a more comprehensive assessment of the potential health effects of ALA as well as to examine whether specific foods rich in ALA are differentially associated with mortality from cancer and other causes, the researchers concluded.

It comes after an anti-cholesterol drug was approved by NICE to be administered in primary care for patients who have already had a cardiovascular event, such as a stroke or heart attack, and are not responding to other cholesterol-lowering treatments.