Eating More Than 22% of Daily Calories from Protein May Raise Heart Disease Risk, Says New Research

A new study conducted by a team of researchers at the University of Pittsburgh (Pitt) School of Medicine has revealed a link between high protein intake and an increased risk of atherosclerosis, a condition where arteries become narrow and hardened due to a buildup of plaque made up of fat, cholesterol and other substances. 

The study, published on February 19th, 2024, in Nature Metabolism, showed that consuming more than 22% of daily calories from protein may increase heart disease risk. The author hypothesized this was by protein elevating immune cell activity associated with atherosclerotic plaque build-up. These findings challenge the popular belief that consuming high amounts of protein is beneficial for optimal health and well-being. Keep reading to discover more about the study’s findings and how your protein intake may affect your heart health.

Related: 6 Signs You Could Be Eating Too Much Protein

What the Study Found 

To arrive at these conclusions, Pitt researchers combined small human trials with experiments in mice and cells. They discovered that amino acids, the building blocks of protein, can cause disease by changing how cells work, especially immune cells in blood vessels called macrophages, leading to atherosclerosis.

Lead researcher Babak Razani, MD, PhD, a professor of cardiology at Pitt, highlighted how crucial these findings are for understanding the possible dangers of overeating protein. “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,” said Razani in a statement.

The study’s findings are particularly relevant in the context of the typical American diet, which tends to be high in protein and mostly from animal sources. The researchers noted that nearly a quarter of the U.S. consumes more than 22% of their daily calories from protein alone.

Building on their previous research, which found that excess protein intake increases atherosclerosis risk in mice, Razani’s team collaborated with metabolism expert Bettina Mittendorfer, Ph.D., of the University of Missouri, Columbia, to further investigate protein’s underlying mechanisms and how they relate to humans.

“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,” said Mittendorfer.

The research also found that leucine—a type of amino acid found in foods like beef, eggs and milk—may play a significant role in causing atherosclerosis. This means that leucine could be a primary reason why overconsuming protein is linked to an elevated heart disease risk. Additionally, plant-based proteins are generally significantly lower in leucine than animal proteins, so it may benefit your heart health to add more high-protein plant-based foods into your eating pattern. 

Razani emphasized that while protein is essential for health, moderation is key. “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,” he explained.

While these findings reveal the potential risks of consuming too much protein, it’s essential to remember that this is just one study. More research is needed to confirm whether a protein intake exceeding 22% of daily calories is safe, especially considering that the 2020-2025 Dietary Guidelines for Americans recommends getting 10 to 35% of daily calories from protein. Try to opt for nutrient-dense protein options, such as fish, legumes, poultry and beans whenever possible.

Related: How Much Protein Do You Need to Eat Every Day?

The Bottom Line 

New research from the University of Pittsburgh School of Medicine suggests that getting more than 22% of your daily calories from protein may cause atherosclerosis (hardening of the arteries), thereby increasing your heart disease risk. Specifically, the amino acid leucine found in animal protein sources was associated with causing atherosclerosis. However, it’s worth noting that this is one study and that protein is an essential macronutrient required for optimal health and well-being. If you have any questions about your protein intake, speak with your doctor or a registered dietitian to learn more.

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