Harvard Study Says Plant Proteins Better For Heart Health Than Meat & Dairy

A new study shows that a higher ratio of plant proteins compared to animal-based foods can improve heart health, just as the US mulls dietary guidelines calling for a shift away from meat.

For months, plant-based meat makers like Beyond Meat and Impossible Foods have banged on about the health benefits of their products, with a deep focus on heart health, the leading cause of mortality in the US, causing a death every 33 seconds.

These claims have been backed up by nutritionists and medical experts, and new research by scientists at the Harvard TH Chan School of Public Health gives them further weight. While several studies have explored the link between plant-based food and heart wellness, this paper specifically investigated the ratio of plant-to-animal protein, and how that impacts cardiovascular health.

This is because while many dietary guidelines recommend a greater portion of plant-based foods, most don’t set an exact proportion. The average American, for example, 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 cardiovascular disease,” said lead author Andrea Glenn. “For coronary heart disease prevention, a ratio of 1:1.3 or higher should come from plants.”

The findings come around the same time as scientific experts responsible for the US national dietary guidelines have submitted a recommendation to cut red meat in favour of a shift towards more plant-forward eating.

More plants = better heart health

The Harvard researchers assessed 30 years of data on the diets, lifestyle and heart health of over 200,000 Americans enrolled in various health studies. Participants reported their dietary intake every four years, which included specific intakes of animal and plant protein. Over the period of the study, the researchers documented over 16,000 cases of cardiovascular disease.

Americans who consume the highest amount of plants (a ratio of 1:3 in favour of animal proteins) were found to have a 19% lower risk of cardiovascular disease, and 27% lower risk of coronary heart disease, compared to those with the lowest plant-to-animal intake (1:4.2).

These risk reductions were higher among participants who ate more protein, contributing to 21% of their overall energy intake. When these people adhered to a higher plant-to-animal ratio, the chances of cardiovascular and coronary heart disease were reduced by 28% and 36%, respectively, when compared to diets where protein made up 16% of the energy consumption.

And in a substitution analysis, the Harvard researchers found that replacing 3% of energy from meat and dairy with plant-based proteins lowered the likelihood of cardiovascular disease and coronary artery disease by 18% and 24%, respectively.

Plus, while stroke risk wasn’t strongly linked with the ratios above, it was associated with a lower risk when red and processed meat were replaced with refined grains and potatoes, whole grains, and nuts.

The researchers further discovered that at a 1:2 ratio, plant protein stopped having added benefits for cardiovascular disease – but the risk for coronary heart disease continued to decrease at higher plant-to-animal ratios.

They ascribed these benefits to the fact that plant proteins are lower in saturated fat and higher in unsaturated fat, carbohydrates, and fibre than meat and dairy. They also have advantageous amino acid profiles, including higher arginine levels (which helps blood pressure), lower branched-chain amino acids (linked with cardiovascular disease risks), and higher bioactive and polyphenol content.

Harvard study proves that US needs to recommend meat reduction

Replacing red and processed meat with plant protein sources – particularly nuts and legumes – was found to improve cardiometabolic risk factors, including blood lipids and blood pressure as well as inflammatory biomarkers.

“Most of us need to begin shifting our diets toward plant-based proteins,” said senior author Frank Hu. “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.”

Dietary ratios have been under the spotlight in Europe, with retailers upping their plant-based offerings to meet climate goals. But even national dietary guidelines have focused on this – Germany’s revised recommendations call for a 75% plant-based diet.

And now, the US is getting in on the act. For the forthcoming update, covering the 2025-30 period, scientists have recommended the government advise Americans to cut back on red and processed meats, and shift their focus to plant-based foods, including vegetables, fruits, legumes, whole grains, and nuts.

The advisory committee has also proposed a change to the protein food group in an effort to deprioritise meat. This would see peas, beans and lentils move from the vegetable to the protein category, and – alongside soy products, nuts and seeds – be listed above meat, poultry, eggs and seafood. It further suggests that fortified soy milk and yoghurt shouldn’t be referred to as “alternatives” because they’re part of the dairy group.

It’s a big shift from the status quo, and even if the guidelines don’t heavily influence how individual Americans eat, they do have important implications for school lunches, the food companies manufacture, and public health efforts.

Now that the report is with the US Department of Agriculture and Department of Health and Human Services, the public has 60 days to submit comments, and the agencies will take everything into consideration and release the official guidelines by the end of 2025.

There’s no guarantee that these proposals will be taken up by the government, especially under a steak-loving president in Donald Trump. But this Harvard study is further proof that they should.