While a high-protein diet may have health benefits, not all protein is equal - eating lots of red meat raises the risk of having a stroke while poultry lowers it, according to a US study.
"The main message from this paper is that the type of protein or the protein package is really important for the risk of stroke," Frank Hu at the Harvard School of Public Health said of the study, which was published in the journal Stroke.
"We have to consider protein in the context of the foods."
Hu and a team of researchers collected data from two massive health surveys that tracked nearly 130,000 men and women from roughly middle age to their senior and elderly years.
Over the 20-some years of the study, nearly 1,400 men and more than 2,600 women had a stroke.
To see what influence different types of dietary protein had on the risk of stroke, the researchers divided up the people in the study based on how much red meat, poultry, fish, dairy and other sources of protein they typically ate each day.
Men who ate more than two servings of red meat each day, which was at the high end of the meat eaters, had a 28 per cent increased risk of stroke compared to men who on average had a third of a serving of red meat each day, the low end of the meat eaters.
Women who ate nearly two servings of red meat a day had a 19 per cent higher risk of stroke than women who ate less than half a serving each day.
Swapping in one serving of poultry lowered stroke risk by 27 per cent, a serving of nuts or fish was linked to a 17 per cent drop, and a serving of dairy dropped the risk by 10 to 11 per cent.
A serving of red meat was considered to be 113 to 170 grams (4 to 6 oz) of beef, or a hamburger patty. A serving of poultry was considered to be 113 grams.
People who ate the most chicken or turkey each day, about a half serving for women and three-quarters of a serving for men, had a 13 per cent reduced risk of stroke compared with those who ate barely more than a serving a day.
Researchers did not prove that beef is to blame for the increased number of strokes, but Adam Bernstein, lead author of the study, said it could be that the fat and iron in red meat play a role.
An earlier study led by Susanna Larsson at the Karolinska Institute in Stockholm, Sweden, also found that eating red meat had a link to the risk of stroke.
"I do not think that poultry has been considered as a protein source that might lower the risk of stroke. This is new," Larsson told Reuters Health in an email.
One surprise was that fish seemed to offer no protection against stroke, although Bernstein said it was possible that the benefits of fish depend on how it's served.
"There's a lot of variation in how people cook and prepare fish, and we couldn't get down to that level," he said.