Higher intake of vegetable fats from foods such as olive oil and nuts is associated with a lower risk for stroke, whereas people who eat more animal fats, especially processed red meats, may have a higher stroke risk, observational findings suggest.
In a study of more than 117,000 health professionals who were followed for 27 years, those whose diet was in the highest quintile for intake of vegetable fat had a 12% lower risk for stroke, compared with those who consumed the least amount of vegetable fats.
Conversely, having the highest intake of animal fat from nondairy sources was associated with a 16% increased risk of stroke.
Fenglei Wang, PhD, presented these results at the American Heart Association scientific sessions.
“Our findings support the Dietary Guidelines for Americans and dietary recommendations by AHA,” Dr. Wang, a postdoctoral fellow in the department of nutrition at Harvard University’s T.H. Chan School of Public Health in Boston, told this news organization.
“The main sources of vegetable fat have a large overlap with polyunsaturated fat, such as vegetable oils, nuts, walnuts, and peanut butter,” Dr. Wang noted, adding that fish, especially fatty fish, is a main source of polyunsaturated fat and is recommended for cardiovascular health.
“We would recommend that people reduce consumption of red and processed meat, minimize fatty parts of unprocessed meat if consumed, and replace lard or tallow (beef fat) with nontropical vegetable oils, such as olive oil, corn, or soybean oils in cooking, to lower their stroke risk,” she said.
Moreover, although the results from this study of dietary fat are informative, Dr. Wang continued, “there are other dietary factors (fruits, vegetables, salt, alcohol, et cetera), and lifestyle factors (physical activity, smoking, et cetera), that are associated with stroke risk and worthy of attention as well.”
“Many processed meats are high in salt and saturated fat, and low in vegetable fat,” Alice H. Lichtenstein, DSc, an AHA spokesperson who was not involved with this research, noted in a press release.
“Research shows that replacing processed meat with other protein sources, particularly plant sources, is associated with lower death rates,” added Dr. Lichtenstein, the Stanley N. Gershoff professor of nutrition science and policy at Tufts University in Boston, and lead author of the AHA’s 2021 scientific statement, Dietary Guidance to Improve Cardiovascular Health.
“Key features of a heart-healthy diet pattern,” she summarized, “are to balance calorie intake with calorie needs to achieve and maintain a healthy weight; choose whole grains, lean and plant-based protein, and a variety of fruits and vegetables; limit salt, sugar, animal fat, processed foods, and alcohol; and apply this guidance regardless of where the food is prepared or consumed.”
Replace processed meat with plant proteins
The focus on stroke in this study “is important” because, traditionally, studies of diet and cardiovascular health have focused on coronary heart disease, Andrew Mente, PhD, who also was not involved in this research, said in an email to this news organization.
“Overall, the take-home message from the study is that replacing processed meat with plant sources of protein in the diet is probably beneficial,” Dr. Mente, associate professor, health research methods, evidence, and impact, Faculty of Health Sciences, McMaster University, Hamilton, Ont., said.
The finding that people who ate the most vegetable fat had a modest 12% lower risk of stroke than those who ate the least vegetable fat “points to protective effects of foods like seeds, nuts, vegetables, and olive oil, which has been shown previously,” he continued.
The highest quintile of total red meat intake was associated with an 8% higher risk for stroke, but this was driven mainly by processed red meat (which was associated with a 12% higher risk for stroke). These findings are “generally consistent with cohort studies showing that processed meat, as with most highly processed foods for that matter, are associated with an increased risk of cardiovascular events,” Dr. Mente noted.
“Surprisingly, dairy products (such as cheese, butter, or milk) in the study were not connected with the risk of stroke,” he added. This finding differs from results of meta-analyses of multiple cohort studies of dairy intake and stroke and the recent large international PURE study, which showed that dairy intake was associated with a lower risk for stroke.
“What is needed to move the field forward,” according to Dr. Mente, “is to employ new methods that use cutting-edge technology to study nutritional biomarkers and health outcomes.”
“When dealing with modest associations as usually encountered in nutrition, it is a challenge to make causal connections based on dietary questionnaires, which are fraught with measurement error,” he added. “The use of novel methods is where the field is headed.”