They discover why excess protein in the diet damages arteries

The atherosclerosis It is a disease in which hardening and narrowing of the arteries occurs as a result of the accumulation of fatty plaques, cholesterol and other substances on the walls of the arteries. These plaques are known as atheromas or atherosclerotic plaques and can hinder blood circulation or rupture, causing blood clots that can also obstruct blood flow and contribute to the development of cardiovascular pathologies (heart attacks, strokes, etc.).

The problem is that it is a silent enemy, as it develops over many years, and in many cases there are no symptoms until an artery has become so narrowed or blocked that it cannot supply the necessary amount of blood to the organs and tissues. . That is why it is very important to prevent and control the factors that favor its appearance and, according to new research, a excess of proteins in the daily diet could increase the risk of atherosclerosis.

The study was carried out by researchers at the University of Pittsburgh School of Medicine, who discovered a molecular mechanism involved in this problem. Their work has combined small human trials with experiments in mice and Petri dish cells, and has shown that ingesting more than 22% of dietary calories from protein can lead to greater activation of immune cells involved in the formation of atherosclerotic plaques, and increase the risk of the disease.

Furthermore, scientists discovered that the leucine amino acid appears to play a disproportionate role in activating pathological pathways associated with atherosclerosis or hardened and stiff arteries. “Our study shows that increasing protein intake in pursuit of better metabolic health is not a universal solution. “You could be causing real damage to your arteries,” stated the Dr. Razani roundprofessor of cardiology at Pitt and senior author.

“Our hope is that this research will launch a dialogue about ways to modify diet in a precise way that can influence body function at a molecular level and reduce disease risks,” he adds. The findings have been published in the journal Nature Metabolism.

An amino acid implicated in the risk of atherosclerosis

In a balanced diet, it is recommended that approximately 10-15% of total calories come from protein, although the exact amount may vary depending on individual factors such as age, sex, level of physical activity, and the presence of certain healthy conditions. The idea that dietary protein is essential for healthy living is widespread today, Razani said, but he and other groups have shown that an overreliance on protein may not be as beneficial for long-term health.

Following their 2020 research, in which Razani’s lab showed for the first time that excess dietary protein increases the risk of atherosclerosis in mice, their next study, in collaboration with Bettina Mittendorfer, a metabolism expert at the University of Missouri (Columbia), delved into the potential mechanism and its relevance to the human body.

The teams of both scientists combined their expertise in cell biology and metabolism and performed a series of experiments in various models, from cells to mice and humans. “We have shown in our mechanistic studies that amino acids, which are actually the building blocks of protein, can trigger diseases through specific signaling mechanisms and also alter the metabolism of these cells,” explained Mittendorfer. “For example, small immune cells in the vasculature called macrophages “can trigger the development of atherosclerosis.”

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

“It is important to look at the diet as a whole and suggest balanced meals that do not inadvertently exacerbate cardiovascular conditions, especially in people at risk”

The results showed that consuming more than 22% of daily dietary calories through protein can negatively affect macrophages responsible for clearing cellular debris and lead to the accumulation of a “cemetery” of these cells within the vessel walls. and worsen atherosclerotic plaques over time.

Interestingly, analysis of circulating amino acids showed that leucine, an amino acid enriched in foods of animal origin such as beef, eggs and milk, is mainly responsible for abnormal activation of macrophages and the risk of atherosclerosis, suggesting a Possible avenue for future research on personalized diet modification or “precision nutrition.”

The findings are particularly relevant in hospital environments, where nutritionists often recommend protein-rich foods for the sickest patients in order to preserve muscle mass and strength. “Maybe blindly increasing the protein load is wrong,” Razani warned. “Instead, it is important to look at the diet as a whole and suggest balanced meals that do not inadvertently exacerbate cardiovascular conditions, especially in people at risk for heart disease and vascular disorders,” she concludes.

Joe Millwardemeritus professor of Human Nutrition at the University of Surrey, who was not involved in the study, said, speaking to SMC UK: “Firstly, the epidemiology of dietary protein intake and health and diseases shows some evidence supporting animal data for an adverse link with cardiovascular disease and mortality, although the strongest evidence points to a beneficial protective effect of plant protein intake. “It is unknown whether this is due to lower leucine in plant proteins, as the authors suggest, or more likely to a better provision of protective micronutrients through plant-based diets.”

“Second, high-protein diets during weight loss are less likely to induce atherosclerosis, because a negative energy balance reduces CVD risk factors and may improve insulin resistance. Third, there are adaptive mechanisms in humans that increase the capacity for rapid elimination of amino acids after a meal in subjects who habitually consume high protein intake, so that the increases in leucine concentrations observed here in monocytes “Humans may be less marked and harmful after such adaptation.”

“Overall, this new article is a very important contribution to the debate on dietary proteins, especially given the well-known environmental cost of the production of proteins of animal origin and the need to reduce excessive consumption in developed countries,” concludes the expert.