Eating too much protein greatly increases heart disease risk

Scientists have discovered potential heart health risks associated with high-protein diets, particularly in relation to atherosclerosis — a condition characterized by hardened and narrowed arteries.

The study, led by the University of Pittsburgh School of Medicine, reveals a complex molecular mechanism by which excessive protein intake, specifically more than 22% of daily calories from protein, may elevate the risk of developing atherosclerosis.

Why too much protein can harm your heart

The collaborative research, integrating small human trials with animal and cellular studies, highlights the significant role of the amino acid leucine, found abundantly in animal products like beef, eggs, and milk, in promoting the disease.

Leucine was identified as a key player in activating immune cells that contribute to the buildup of atherosclerotic plaques, thereby increasing disease risk.

Babak Razani, M.D., Ph.D., a professor of cardiology at Pitt and a senior author of the study, cautions against the unbridled increase in protein consumption in the pursuit of better metabolic health.

“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, M.D., Ph.D.

“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.”

This research builds on Razani’s earlier work in 2020, which first indicated the link between high dietary protein and increased atherosclerosis risk in mice.

From petri dishes to people: Tracing protein’s effects

Further investigation, in collaboration with Bettina Mittendorfer, Ph.D., a metabolism expert at the University of Missouri, Columbia, aimed to understand the underlying mechanisms and their relevance to humans.

The study’s comprehensive approach, spearheaded by Xiangyu Zhang, Ph.D., and Divya Kapoor, M.D., first authors, alongside Mittendorfer’s team, explored the impact of amino acids on disease progression through detailed experiments across cellular, mouse, and human models.

“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,” Mittendorfer said. “For instance, small immune cells in the vasculature called macrophages can trigger the development of atherosclerosis.”

Their findings suggest that excessive protein intake disrupts the function of macrophages — immune cells critical in clearing cellular debris — leading to the worsening of atherosclerotic conditions.

Finding your protein ‘sweet spot’ for optimal heart health

Interestingly, the research also touches on the potential benefits of “precision nutrition,” hinting at diet personalization as a future avenue to explore for mitigating cardiovascular disease risk without forsaking the benefits of protein, like muscle maintenance and strength, especially in clinical settings.

Razani’s study prompts a reevaluation of protein-rich diets, especially those high in leucine, advocating for a balanced approach to nutrition that considers the holistic impact on cardiovascular health.

The findings underscore the necessity of further exploration into the optimal protein intake that maximizes health benefits while minimizing risks, particularly for individuals at risk of heart disease and related conditions.

Moreover, Razani highlights the intriguing possibility that the differences in cardiovascular impacts between plant-based and animal-based proteins could be attributed to their varying leucine levels.

“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.”

Looking ahead: The future of dietary guidelines

In summary, this disturbing research illuminates the complex relationship between high dietary protein intake and increased risk of atherosclerosis, highlighting the pivotal role of the amino acid leucine in this process.

By meticulously combining small-scale human trials with mouse and cell experiments, this study challenges the prevailing notion that more protein equates to better health and promotes nuanced dietary strategies aimed at optimizing cardiovascular health.

The findings underscore the importance of moderation and balance in protein consumption, paving the way for future investigations into precision nutrition that could tailor dietary recommendations to individual health needs and potentially revolutionize how we approach diet and disease prevention.

The full study was published in the journal Nature Metabolism.

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