Research, published in the journal Neurology, found that overall, participants with the highest protein intakes were 20% less likely to have a stroke than those with the lowest intakes.
The study’s lead author Dr Xinfeng Liu of the Nanjing University School of Medicine in China said this amount of protein was moderate considering the possible impact. “Additional, larger studies are needed before definitive recommendations can be made, but the evidence is compelling,” he said.
Within this the association was stronger for animal protein than vegetable, although the intake range for vegetable protein was smaller than meat-derived protein. The Chinese researchers said the results pointed towards upping intakes of proteins like fish and chicken – not necessarily red meats, which have been linked in the past with increased stroke risk.
Dr Liu said: “These results indicate that stroke risk may be reduced by replacing red meat with other protein sources, such as fish.”
The meta-analysis pooled data from seven prospective studies involving 254,489 participants – who were followed for an average of 14 years.
Animal, vegetable, mineral
Within these studies participants filled out diet questionnaires or were asked to recall everything they had consumed in the previous 24 hours. Stroke incidence was then recorded in the follow-up period.
“In our study, the reduced risk of stroke was more evident for animal protein than vegetable protein. A possible interpretation is that the range of protein intake between the highest and lowest categories was narrower for vegetable protein (15.6 grams per day) than for animal protein (34.7 grams per day) in our meta-analysis, which made it more difficult to observe a statistically significant association.
“Among different protein sources, fish consumption has been associated with decreased risk of stroke, whereas red meat consumption has been associated with increased stroke risk,” they wrote.
They suggested this association could be due to protein’s blood pressure–lowering effect.
Dr Liu said that if everyone's protein intake were at this higher level, this would translate to more than 1.4 million fewer deaths from stroke each year worldwide and therefore a decreased occurrence of disability from stroke too.
Two of the seven studies were conducted in Japan (8506 of the participants combined), where red meat intakes are generally lower and fish is eaten more commonly, the researchers said. Four of the studies were conducted in in the US (211,313 participants combined), while the remaining one took place in Sweden (34,670).
Factors that could also have an effect on risk levels such as smoking and high cholesterol were accounted for, they wrote.
Published online before print, doi: 10.1212/WNL.0000000000000551
“Quantitative analysis of dietary protein intake and stroke risk”
Authors: Z. Zhang, G. Xu, F. Yang, W. Zhu and X. Liu