High intakes of trans-fatty acids, an enfant terrible of the food industry, may increase the risk of stroke in post-menopausal women by 30 per cent, says a new study.
Dietary fat in general was also associated with a 40 per cent increased risk, compared to women who ate the least amount, according to findings presented at the American Stroke Association's International Stroke Conference 2010.
Researchers from the University of North Carolina in Chapel Hill claim that this is the first study to examine the associations of different fats and different subtypes of ischemic stroke in post-menopausal women.
According to the American Heart Association, someone in the US has a stroke every 40 seconds, with an average of about 800,000 documented every year. Postmenopausal women reportedly face a higher stroke risk than men of a similar age.
“I think our findings support the American Heart Association recommendations for keeping trans fat intake at less than 1 percent of energy,” said senior author Ka He, associate professor of nutrition and epidemiology at the UNC.
Trans fats and heart health
Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil (PHVO) that converts the oil into semi-solids for a variety of food applications.
Trans fats are attractive for the food industry due to their extended shelf life and flavour stability, and have displaced natural solid fats and liquid oils in many areas of food processing.
But scientific reports that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD), has led to a well-publicized bans in places like New York City.
Denmark introduced legislation in 2004 that required locally and imported foods to contain less than two per cent industrially made TFAs, a move that effectively abolished the use of partially hydrogenated vegetable oils in the country.
In the food industry this has been mirrored by an increase the in pressure on food manufacturers to reduce or remove trans fatty acids from their products and reformulate.
Data from 87,230 post-menopausal women aged between 50 to 79 participating in the Women's Health Initiative (WHI) Observational Study was used to elucidate if there was a relationship between fat intake, and trans fats in particular, with the risk of stroke.
According to the UNC researchers, during an average of 7.6 years of follow-up 1,049 ischemic strokes were documented.
Statistical analysis showed that women who consumed the highest average quantities of trans fat – about seven grams a day – were 30 per cent more likely to suffer stroke than women who consumed about one gram per day. The most common sources of trans fat identified were processed and fried foods, said the researchers.
When they considered total fat intakes, Dr He and his co-workers found that the highest average intakes, equivalent to about 86 grams per day, were 40 per cent more likely to suffer stroke than women wit the lowest average intakes, equivalent to about 26 grams a day.
The study was sponsored by the National Institutes of Health and the National Heart, Lung and Blood Institute.
Source: American Stroke Association's International Stroke Conference 2010
“Total fat, trans fat linked to higher incidence of ischemic stroke”
Authors: S. Yaemsiri, S. Sen, L. Tinker, W. Rosamond, S. Wassertheil-Smoller, K. He