The study team found that those in the top tenth for red meat consumption, who ate at least 102g daily, were 42% more likely to suffer an ischemic stroke compared to women who ate less than 25g of red meat daily.
Diets heavy in red meat have been linked to a number of ill effects, including an increased risk of certain cancers, heart disease, and hypertension. Yet just three studies have looked at red meat and stroke risk. One study found a link, but the others did not.
To investigate further, Dr Susanna Larsson of the Karolinska Institutet in Stockholm and her colleagues looked at data on 34,670 women 39 to 73 years old. All were free of cardiovascular disease and cancer at the beginning of the study in 1997.
During 10 years of follow-up, 1680 (5%) had a stroke, with 78% due to cerebral infarction.
When the researchers divided women into five groups based on how much red meat they reported eating, they found that those in the top fifth, who ate at least 86g/day were at 22% greater risk of cerebral infarction than women in the bottom fifth (less than 36.5g).
Women who ate the most processed meat (at least 41.3g a day) were at 24% greater risk than women who consumed the least (less than 12.1g per day).
However, there was no link between consumption of red or processed meat and risk of other types of stroke, nor was there any relationship between fresh meat consumption or poultry consumption and any type of stroke.
Red meat increased stroke risk in non-smokers, but not smokers, and in women who didn't have diabetes, but not in women with diabetes. For non-smokers and non-diabetics in the top tenth of red meat consumption, the risk of cerebral infarction was 68% greater.
Several mechanisms could explain the link between red meat and processed meat and stroke risk, the researchers say.
For example, both types of meat have been tied to hypertension. Also, iron in red meat might also accelerate the production of tissue-damaging free radicals. Further, Larsson and her team point out, processed meats are high in sodium.
(Reuters Health, January 2011)