Turns out, there is such a thing as too much protein.
A new study published in the journal Nature Metabolism suggests that eating too much protein is bad for your arteries.
“Our study shows that dialing up your protein intake in pursuit of better metabolic health is not a panacea. You could be doing real damage to your arteries,” senior and co-corresponding author Babak Razani, MD, Ph.D., professor of cardiology at the University of Pittsburgh, said in a statement.
Researchers from Pitt’s School of Medicine found that consumption of excessive protein can lead to atherosclerosis, which is the buildup of fats, cholesterol and other substances in and on the artery walls.
The buildup, also called plaque, can cause the arteries to narrow, blocking blood flow, or burst, which can lead to a blood clot.
If more than 22% of dietary calories come from protein, it can lead to increased activation of the immune cells that play a part in blood plaque forming in the arteries.
Data collected from over the past decade found that Americans consume a lot of protein — mostly from animals — and nearly a quarter of the US population gets over 22% of all daily calories from just protein.
Razani proposed that the trend of high consumption of protein is most likely due to the common idea that dietary protein is essential to a healthy lifestyle — but too much could be detrimental in the long term.
According to the National Institutes of Health, to maintain weight, women should eat 2,000 calories per day on average, and men should eat 2,500 calories per day.
Therefore, on average, if women consume more than 440 calories of protein and men consume more than 550 calories of protein, there could be a risk of causing damage to the arteries.
Foods considered to be high in protein include eggs, meat, fish and lentils.
“Our hope is that this research starts a conversation about ways of modifying diets in a precise manner that can influence body function at a molecular level and dampen disease risks,” Razani shared.
The study looked at a combination of small human trials and experiments in mice and cells in a petri dish.
Razani and Dr. Bettina Mittendorfer, a metabolism expert at the University of Missouri, Columbia, teamed up to examine protein’s relevance to the human body.
Researchers also found that leucine — an essential amino acid and nutrient-based signal to activate protein synthesis — is primarily responsible for abnormal macrophage, which is the activation of white blood cells and a risk of atherosclerosis.
“We have shown in our mechanistic studies that amino acids, which are really the building blocks of the protein, can trigger disease through specific signaling mechanisms and then also alter the metabolism of these cells,” Mittendorfer said. “For instance, small immune cells in the vasculature called macrophages can trigger the development of atherosclerosis.”
The differences in levels of leucine between diets with plant and animal protein could be the reasoning behind the different effects on the heart, blood vessels and metabolic health, the findings show.
The study findings are particularly important for nutritionists in hospital settings who often recommend that their sickest patients have a protein-rich diet in order to preserve muscle mass and strength.
“Perhaps blindly increasing protein load is wrong,” Razani suggested. “Instead, it’s important to look at the diet as a whole and suggest balanced meals that won’t inadvertently exacerbate cardiovascular conditions, especially in people at risk of heart disease and vessel disorders.
“The potential for this type of mechanistic research to inform future dietary guidelines is quite exciting.”
