A new study led by researchers at Harvard T.H. Chan School of Public Health suggests that increasing the proportion of plant-based protein in your diet may lower the risk of cardiovascular disease and coronary heart disease. The findings, published on Dec. 2 in the *American Journal of Clinical Nutrition*, indicate that replacing red and processed meats with plant protein sources, such as nuts and legumes, could be key to these health benefits.
The study, the first of its kind to explore the ideal ratio of plant to animal protein, found that a higher intake of plant protein is linked to a lower risk of heart disease. The researchers observed that a combination of consuming more plant-based protein and overall higher protein intake resulted in the greatest benefits for heart health.
In the U.S., the typical plant-to-animal protein ratio is about 1:3, but the study suggests that a ratio of at least 1:2 is more effective in preventing cardiovascular disease. For coronary heart disease, the researchers recommend a ratio of 1:1.3 or higher.
Lead author Andrea Glenn, a visiting scientist in the Department of Nutrition at Harvard Chan School and assistant professor at NYU Steinhardt, explained that shifting the balance of protein sources could play a significant role in preventing heart disease. “Our findings suggest that the ratio of plant to animal protein should be higher than what most Americans currently consume,” Glenn said.
The study followed nearly 203,000 participants over 30 years, using data from the Nurses’ Health Studies I and II and the Health Professionals’ Follow-up Study. Participants reported their diets every four years, allowing the researchers to track their protein intake and heart health. Over the course of the study, 16,118 cases of cardiovascular disease, including over 10,000 cases of coronary heart disease, were documented.
After adjusting for various factors, the study found that those who consumed a higher ratio of plant to animal protein had a 19% lower risk of cardiovascular disease and a 27% lower risk of coronary heart disease compared to those with the lowest plant-to-animal protein ratio. Among those who consumed more protein overall, the reductions in risk were even greater, with a 28% lower risk of cardiovascular disease and a 36% lower risk of coronary heart disease.
While the study did not find a strong link between the plant-to-animal protein ratio and stroke risk, it did show that replacing red and processed meats with plant-based proteins, particularly nuts, was associated with a lower risk of stroke.
The researchers also investigated whether there is a point at which increasing plant protein intake no longer provides additional benefits. They found that the benefits of a higher plant-to-animal protein ratio plateaued at a 1:2 ratio for cardiovascular disease, but coronary heart disease risk continued to decrease as the ratio increased.
According to the study’s authors, replacing red and processed meat with plant proteins may improve heart health by reducing blood lipids, blood pressure, and inflammation. Plant proteins are also rich in fiber, antioxidants, vitamins, and healthy fats, which contribute to better cardiometabolic health.
Senior author Frank Hu, a professor of nutrition and epidemiology at Harvard Chan School, emphasized the need for people to shift toward plant-based proteins. “We can reduce our meat consumption, especially red and processed meats, and incorporate more legumes and nuts into our diets. This not only benefits our health but also supports the well-being of the planet,” Hu said.
While the study offers important insights, the researchers cautioned that further research is needed to determine the optimal balance of plant and animal protein for heart health, as well as its potential impact on stroke risk.
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