Steak and potatoes a staple? Eating too much protein in a day can have massive heart implications

A fresh study warns that consuming high-protein diets, especially those where more than 22 percent of daily calories come from protein, may contribute to the development of atherosclerosis, or hardening of the arteries, leading to heart health issues.

Using both animal and small-scale human trials, researchers from the University of Pittsburgh discovered that excess protein, particularly the amino acid leucine found in animal-based sources such as meat and eggs, triggers mTOR signaling in macrophages – key immune cells involved in arterial plaque formation.

“Eating meals containing about 22 percent kilocalories of protein is the threshold at which the protein and its leucine elevate risk,” lead author Dr. Babak Razani said in the study published Wednesday in the journal Nature Metabolism.

But not all experts agree. A 2020 study by Razani’s team linked high-protein diets to greater cardiovascular disease risk.

A larger 2023 human study found no statistically significant difference in cardiovascular outcomes between high and standard‑protein diets.

Dr. Stephen Tang, a cardiologist not involved in the research, claimed the study was too small to make any conclusions. Yet, he agrees it points to a growing indication that heart specialists are increasingly favoring plant‑forward diets.

“I would not do anything different,” Tang told Medical News Today. “However, it does provide more evidence that high protein is not the way to go. Cardiologists are traditionally focused on cholesterol and high blood pressure, not protein. This study confirms that a plant-based diet is good for heart health.”

A 1984 study defined plant-based protein as coming from foods such as bread, vegetables, fruits, nuts, beans and pasta. Women who consumed more of these were 46 percent more likely to age healthily, while those who relied on animal proteins were 6 percent less likely to remain healthy with age.

Current dietary guidelines generally recommend that protein should comprise 10 to 35 percent of daily calories, with a lower end of about 0.8 g per kg of body weight (roughly 11 percent of energy) being sufficient for most adults.

The American Heart Association also says that protein quality is critical. It endorses choosing plant-based proteins, such as beans, lentils, nuts, seeds and fatty fish rich in omega‑3s, while limiting red and processed meats and saturated fats.

Harvard researchers also point out that while excessive protein isn’t inherently harmful, relying heavily on animal protein can elevate cholesterol and mortality risk compared to plant protein.