The oils - found in fish like salmon, mackerel and tuna - are known to improve chances of surviving a repeat heart attack.
Researchers at the University of Reading found fish oils have a direct impact on the muscle cells that control the elasticity of our blood vessels.
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At least 39,000 women a year in the UK suffer heart attacks and their chances of dying are higher than a man’s.
Study leader Professor Christine Williams, the University’s first Hugh Sinclair Professor of Nutrition and Pro Vice-Chancellor for Research and Innovation, said: ‘Studies examining women’s heart health are much less common than those which study men, partly because the studies are harder to carry out in women due to the varying effects of hormones during the menstrual cycle.
‘In addition, many believe men are the only ones to suffer from heart disease.
‘However nearly 40,000 women die of coronary heart disease each year in the UK and we do not yet know whether all the diet recommendations which we currently advise are as effective for women as for men.
In the study around 60 people, half men and women, were given test drinks containing either saturated fats or a combination with omega 3 fish oils, equivalent to a 200g portion of oily fish.
Prof Williams said ‘As well as discovering the effect of fish oils is greater in women we also found that people with a gene variation that produces the protein eNOS, which helps to increase blood flow, also benefitted more.
‘Our study showed that people who carry the rarer form of the protein, which is about 10 per cent of the UK population, respond twice as well to fish oils, suggesting they would particularly benefit from additional oily fish intake.
‘This research supports the view that the effects of diets vary, being more effective in certain genders and genotypes. Our study was very carefully designed to include equal numbers of men and women and also equal numbers of people with the two types of gene variants, so that the results are very unlikely to be due to chance. ‘Although the responses varied, all the subjects in the study benefitted from taking fish oils with a meal.
‘However, for women and those with the gene variant, the responses were very marked indeed, and when it comes to their diet could give them considerable health benefits in the future.’ The work was funded by the Biotechnology and Biological Sciences Research Council.
However the researchers found that some of the relaxation effect on the blood vessel wall may be due to direct actions of the fish oil acting on the muscle cells themselves, rather than on the cells lining the blood vessel wall.
Professor Williams added ‘This is an exciting discovery which gives us a new way of looking at how our diet affects the health of our blood vessels, and possibly more effective ways of improving heart health in the future.’ The best dietary source of omega 3 fatty acids is oily fish because the human body cannot produce omega-3 fatty acids.
Fish oil supplements are approved for prescribing on the NHS to patients after a heart attack, or who have metabolic syndrome or high triglycerides - unhealthy blood fats.
Omacor, which is licensed for post-heart attack treatment, has been shown in clinical trials to cut the risk of sudden death by up to 45 per cent.