A large new study by researchers at the University of North Carolina at Chapel Hill has found that postmenopausal women whose diets were high in trans fats (and who did not take aspirin) had a 66% higher risk of ischemic stroke (blood clots in vessels supplying blood to the brain) than those whose diets were the lowest in trans fats.
Those consuming a high-trans fat diet lowered their stroke risk by taking aspirin, but after controlling for other risk factors, aspirin users still had a 39% higher risk of ischemic stroke than those with a low-trans fat diet.
Trans fats are typically found in processed foods, such as margarine and other non-butter spreads, commercially baked products (such as doughnuts, cakes and pies), fried fast foods, processed soups, chips and crackers, cookies, candy and cereals, shortenings and cake mixes, as well as toppings and dips.
The new study, “Trans Fat Intake, Aspirin and Ischemic Stroke Among Postmenopausal Women,” by researchers at the University of North Carolina Gillings School of Global Public Health and colleagues, was published in the March 1, 2012 issue of the journal Annals of Neurology. The new study was supported by a grant from the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.
“Our findings were contrary to at least two other large studies of ischemic stroke,” said one of the study’s authors, Ka He, Sc.D., M.D., associate professor of nutrition and epidemiology at the University of North Carolina Gillings School of Global Public Health. “However, ours was a larger study and included twice as many cases of ischemic stroke. Our unique study base of older women may have increased our ability to detect the association between trans fat intake and ischemic stroke among non-users of aspirin.”
The Study; Methodology
The researchers analyzed data collected from 87,025 generally healthy postmenopausal women aged 50 to 79 as part of the Women’s Health Initiative Observational Study.
The participants’ dietary intake of trans fats and other components of their diets were measured by repeated food frequency questionnaires filled out by the women who participated in the study.
The participants were divided into five groups (quintiles) according to the cumulative average of fat intake they reported in their diets. The quintiles for extent of trans fat intake in their diets, were as follows:
- 1st quintile (lowest) — those that consumed an average 2.2 g of trans fats per day
- 2nd quintile — those that consumed an average 2.3 g of trans fats per day
- 3nd quintile — those that consumed an average 2.6 g of trans fats per day
- 4th quintile — those that consumed an average of 3.4 g of trans fats per day
- 5th quintile (highest) — those that consumed an average of 6.1 g of trans fats per day
During a follow-up period from 1994 to 2005, 1,049 new cases of ischemic stroke were documented among study participants.
The researchers analyzed the data to determine the relationship, if any, between the extent of dietary trans fat intake and incidence of ischemic stroke. They also analyzed the data for any relationship between intake of other kinds of fat (including saturated, monounsaturated or polyunsaturated fat) and ischemic stroke risk.
The researchers found that, among the women who did not take aspirin, those in the 5th quintile, whose diets contained the largest amounts of trans fats, were 66 percent more likely to have an ischemic stroke (blood clots in vessels supplying blood to the brain) than those in the 1st quintile, who ate the least trans fat.
Among aspirin users, and after controlling for other potential factors (such as such as fruit and vegetable and fiber in the diet, as well as socioeconomic factors, use of hormone replacement therapy, smoking and medical history), the women in the 5th quintile, who ate the most trans fats, were 39 percent more likely to have an ischemic stroke than the women who ate the least amount of trans fat.
The impact of dietary trans fat was modified by aspirin use, which was consistent across all three types of trans fat isomers, the researchers found.
“Increased platelet response to an agonist and inhibition after aspirin intake may at least in part explain the attenuated association between trans fat intake and ischemic stroke among aspirin users in this cohort,” the researchers suggested.
The study also found that women who consumed the highest amount of trans fat also were more likely to be smokers, have diabetes, be physically inactive and have lower socioeconomic status than those who consumed the least trans fat.
The researchers did not find any association between eating other kinds of fat (including saturated, monounsaturated or polyunsaturated fat) and risk of ischemic strokes or any ischemic stroke subtypes.
“In this large cohort of postmenopausal women, higher intake of trans fat was associated with incident ischemic stroke independent of major lifestyle/dietary factors. Aspirin use may attenuate the potential adverse effect of trans fat intake on ischemic stroke,” the researchers concluded.
“Our findings highlight the importance of limiting the amount of dietary trans fat intake and using aspirin for primary ischemic stroke prevention among women, especially among postmenopausal women who have elevated risk of ischemic stroke,” said Sirin Yaemsiri, a doctoral student in the epidemiology department of the University of North Carolina’s school of public health, and one of the study authors.
Other experts, including the Mayo Clinic, however, warn that daily aspirin use can have serious side effects, including internal bleeding, and should not be undertaken without your doctor’s recommendation and approval.
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