A study published online by the BMJ today doesn't find evidence of a clear benefit of omega 3 fats on health. These findings do not rule out an important effect of omega 3 fats, but suggest that the evidence should be reviewed regularly, say the researchers. Consumption of long chain omega 3 fatty acids, found in oily fish and fish oils, and a shorter chain omega 3, found in some plant oils, is thought to protect against heart disease. UK guidelines encourage the general public to eat more oily fish, and higher amounts are advised after a heart attack. Researchers analysed 89 studies (48 randomised controlled trials and 41 cohort studies) to assess the health effects of long and short chain omega 3 fats on total mortality, cardiovascular events, cancer, and strokes. (…) Pooling the results showed no strong evidence that omega 3 fats have an effect on total mortality or combined cardiovascular events. The few studies at low risk of bias were more consistent, but they also showed no effect of omega 3 on total mortality or cardiovascular events. (…) They therefore conclude that it is not clear whether long chain or short chain omega 3 fats (together or separately) reduce or increase total mortality, cardiovascular events, cancer, or strokes.