Shifting diets to incorporate more plants and less meat is recommended for environmental and health benefits, including heart health.
Researchers at Harvard T.H. Chan School of Public Health have found that consuming more plant-based than animal-based proteins is associated with a lower risk of cardiovascular diseases (CVD) and coronary heart disease (CHD).
Since most diet recommendations do not mention optimal meal portions, the researchers embarked on a study to examine the associations between different plant-to-animal protein ratios and CVD risk.
They analyzed 30 years of data from approximately 203,000 adults in the US, including diet, lifestyle, and heart health, with dietary intake reported every four years. The study also assessed the joint effects of the plant-to-animal protein ratio with protein density (percentage of total calories from protein) on CVD risk.
Cutting down on meat
The study results suggest that replacing red and processed meats with plant protein sources, particularly legumes and nuts, contributes significantly to the reduced risk of CVD and CHD. Whole plant sources should replace saturated fats and animal proteins, not refined carbohydrates, for improved cardiovascular health, the authors note.
According to the findings, participants with the highest plant-to-animal protein ratio had a 19% lower risk of CVD and a 27% lower risk of CHD. CVD risk reduction plateaus at a 1:2 plant-to-animal protein ratio, whereas CHD risk continues to decrease with higher ratios. However, stroke risk was not significantly associated with protein ratios, though replacing red and processed meats with plant sources was associated with a lower stroke risk.
Regarding the cardiovascular benefits of protein density, they found that higher overall protein intake levels (21% of energy from protein) further emphasize the benefits of a higher plant-to-animal protein ratio.
Plant proteins for health
The researchers argue that the benefits come from plant proteins’ unique characteristics. They are lower in saturated fats and higher in unsaturated fats, carbohydrates, and fiber. They also have beneficial amino acid profiles, such as higher arginine levels, lower BCAAs, and higher glycine.
Therefore, the cardiovascular benefits of plant protein include lower cholesterol levels, blood pressure, and diabetes incidence, as well as lower heme iron and trimethylamine N-oxide production. Nonetheless, the authors recommend ensuring nutrient adequacy, as some nutrients may become deficient when plant protein exceeds 80% of total intake unless fortified foods or supplements are used.
The study stresses the need for more research to clarify the optimal plant-to-animal protein ratio for CVD prevention and to examine its effectiveness in more diverse populations consuming healthier plant proteins.
“Most of us need to begin shifting our diets toward plant-based proteins. We can do so by cutting down on meat, especially red and processed meats, and eating more legumes and nuts.
“Such a dietary pattern is beneficial not just for human health but also the health of our planet,” senior author Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology at Harvard Chan School, told SciTechDaily.
