Plant Protein Comes With a Lower Cardiovascular Disease Risk Than Meat Protein

Anyone keen to look after their heart may want to start eating more soy and less sausages, according to a new study.

After analyzing 30 years of health data from 202,863 participants, researchers from the Harvard TH Chan School of Public Health found that the participants who ate a higher ratio of plant-based proteins to animal-based proteins had a lower likelihood of developing cardiovascular disease (CVD) and coronary heart disease (CHD).

Such a leafy diet, however, didn’t appear to reduce the participants’ risk of experiencing a stroke.

The research was published in the American Journal of Clinical Nutrition.

Plant power

“The average American eats a 1:3 plant to animal protein ratio. Our findings suggest a ratio of at least 1:2 is much more effective in preventing CVD,” lead author Dr. Andrea Glenn, an assistant professor and a visiting scientist in the TH Chan School’s department of nutrition, said in a statement.

“For CHD prevention, a ratio of 1:1.3 or higher should come from plants.”

Glenn and her colleagues arrived at this golden ratio after trawling through the data of three ongoing cohort studies: the Nurses’ Health Study – which began in 1976 and includes health data of female 121,700 nurses – the Nurses’ Health Study II – which began in 1989 and includes data from 116,429 female nurses – and the Health Professionals Follow-up Study – which began in 1986 and includes 51,529 male health professionals.

These data included any diagnoses of CVD and CHD, and answers to dietary questionnaires.

Once adjusted for sociodemographic and lifestyle factors, the data showed that those who received more of their dietary protein from plants, rather than from meat, were less likely to be diagnosed with CVD or CHD.

Compared to participants who consumed the lowest plant-to-animal protein ratio, participants who consumed the highest had a 19% lower risk of CVD and a 27% lower risk of CHD. These reductions were even higher among participants who ate more protein overall.

Those who consumed the most protein (21% of energy coming from protein) and adhered to a higher plant-to-animal protein ratio saw a 28% lower risk of CVD and a 36% lower risk of CHD, compared to those who consumed the least protein (16% of energy).

Glenn said these risk reductions are likely driven by the replacement of red and processed meats, which are known to come with a cardiovascular risk.

No significant associations were found for stroke risk and protein ratio.

Given that the dietary questionnaires didn’t distinguish between processed and non-processed foods, Glenn said more studies will be needed to determine whether processed plant-based foods and non-processed plant-based foods come with different cardiovascular risks.

“Based on the questionnaire, we are unable to determine if most of the foods would be homemade or store bought, or considered UPFs [ultra-processed foods], particularly for the amount of protein coming from plants and animals,” she told Technology Networks.

“For example, we ask about peanut butter intake, but we do not know if it is natural or one that contains added sugars, etc. If we had that type of data, we could create ratios or do analyses where we separate the foods into different categories based on homemade, store bought, consumed at restaurants, UPFs, etc. I can’t say for sure what the data may look like if we did that, but it is possible that some of the less processed sources would look better for CVD prevention, but we would need to do studies on this question to confirm.”

Reference: Glenn AJ, Wang F, Tessier AJ, et al. Dietary plant-to-animal protein ratio and risk of cardiovascular disease in 3 prospective cohorts. Am J Clin Nutr. 2024. doi: 10.1016/j.ajcnut.2024.09.006