We often hear about the benefits of eating more protein, from building muscle to reducing hunger. However, new research is challenging this advice, warning that excessive protein intake might harm cardiovascular health. A study published in Nature Metabolism has revealed a surprising link between high-protein diets and an increased risk of heart disease.
Babak Razani, a cardiology professor at the University of Pittsburgh School of Medicine, points to emerging concerns. “There have been large and well-done epidemiological studies (mostly based on dietary questionnaires) that show increased protein intake correlates with cardiovascular disease“, Razani told Newsweek. Researchers are now delving into the biological mechanisms that explain this connection.
Findings on the link between protein intake and heart disease
Protein is made up of amino acids, which are essential for muscle growth and metabolic functions. However, not all amino acids are equal. The study highlights leucine, a specific amino acid found in protein, as a potential culprit. Researchers discovered that consuming too much leucine can activate a molecular process that promotes the buildup of fats and cholesterol in the arteries, a condition known as atherosclerosis.
In earlier research using mice, Razani’s team demonstrated that high-protein diets flooded the bloodstream with amino acids. Immune cells called macrophages absorb these amino acids, triggering a signaling pathway driven by a molecule known as mTOR. This process caused macrophages to malfunction, exacerbating atherosclerosis. The new study confirms that the same response occurs in human cells.
“We found that even though many amino acids increase in the blood stream after protein ingestion, it is predominantly leucine that activates mTOR and the deleterious signaling pathways in macrophages, the immune cells which are the key driver of atherosclerosis (or cardiovascular disease)”, Razani explained.
The study also looked at how much protein it takes to trigger these effects. Researchers found that consuming protein equivalent to 22% of daily calorie intake significantly activated immune cells. For context, the USDA recommends protein intake at around 15% of daily calories, aligned with a Mediterranean diet.
What does this mean for your diet?
Not all protein sources have the same leucine levels. Animal-based proteins, especially whey found in protein powders, tend to have higher leucine concentrations than plant-based proteins. However, the way proteins are digested and absorbed can influence how leucine impacts the body. “We are working on this as we speak”, Razani said.
The findings highlight the importance of moderation and balance in our diets. Overeating protein, particularly from supplements, might not be as healthy as it seems. Razani advises following the USDA’s dietary guidelines, which emphasize a balanced diet of healthy fats, complex carbohydrates, and moderate protein.
While more research is needed, this study raises critical questions about the long-term effects of high-protein diets. “Blindly eating more protein in your diet for overall metabolic health is not a cure-all”, Razani cautioned.
If you’re considering dietary changes, especially if you have existing heart conditions, consult a healthcare provider first. A Mediterranean-style diet, with its moderate protein content and emphasis on whole foods, remains a heart-healthy choice for most people.
