Too Much Protein Can Damage Your Arteries

Can you be eating too much protein? Is it possible that protein could actually harm the body? Well, a new study from scientists at the University of Pittsburgh found that the consumption of too much protein could damage your arteries.

If you remember, about twenty years ago the Atkins diet was all the rage. That was the one where people were supposed to forgo carbs, like bread, and eat a diet of almost all meats for their high protein content. However, this contradicted the long-standing belief that eating a lot of meat is bad for the body due to the cholesterol and the fat that could lead to problems like clogging the arteries.

Now comes another reason not to eat too many meats or dairy products. University of Pittsburgh School of Medicine researchers discovered a molecular mechanism by which excessive dietary protein could increase atherosclerosis risk. The findings were published in Nature Metabolism today.

Atherosclerosis is a condition where a buildup of plaque, a sticky substance made up of fat, cholesterol, calcium, and other substances, hardens and narrows the arteries. This narrowing reduces blood flow and can lead to serious health problems.

Proteins are complex molecules that are essential for life. They are made up of long chains of amino acids, which are linked together by peptide bonds. There are 20 different types of amino acids, and the specific sequence of amino acids in a protein determines its unique shape and function.

Proteins are essential for the growth and repair of all tissues in the body, including muscle, bone, skin, and blood. They also transport molecules throughout the body, such as oxygen, hormones, and nutrients and provide structure and support to cells and tissues. For example, collagen is a protein that provides structure to skin and bones.

The new study, which combined small human trials with experiments in mice and cells in a Petri dish, showed that consuming over 22% of dietary calories from protein can lead to increased activation of immune cells that play a role in atherosclerotic plaque formation, driving the disease risk. Furthermore, the scientists showed that one amino acid – leucine – seems to have a disproportionate role in driving the pathological pathways linked to atherosclerosis, or stiff, hardened 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,” said senior and co-corresponding author Babak Razani, M.D., Ph.D., professor of cardiology at Pitt. “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.”

Based on initial experiments in healthy human subjects to determine the timeline of immune cell activation following ingestion of protein-enriched meals, the researchers simulated similar conditions in mice and in human macrophages, immune cells that are shown to be particularly sensitive to amino acids derived from protein.

Their work showed that consuming more than 22% of daily dietary calories through protein can negatively affect macrophages that are responsible for clearing out cellular debris, leading to the accumulation of a “graveyard” of those cells inside the vessel walls and worsening of atherosclerotic plaques overtime. Interestingly, the analysis of circulating amino acids showed that leucine – an amino acid enriched in animal-derived foods like beef, eggs and milk – is primarily responsible for abnormal macrophage activation and atherosclerosis risk, suggesting a potential avenue for further research on personalized diet modification, or “precision nutrition.”

“Perhaps blindly increasing protein load is wrong,” Razani said. “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.”