Your Heart Disease Risk Could Go Up 22% if Your Calories Come from This Surprising Source, According to New Research

Beth Ann Mayer
·6-min read

Woman cooking food with protein on the stove

Protein is a vital nutrient. One scroll through certain corners of TikTok will take you through video after video of users swearing by high-protein diets to bulk up, get stronger and keep weight and even stress in check. The last two—weight and stress management—are often linked with lower risks of heart disease. 

However, a new study out of the University of Pittsburgh (Pitt) School of Medicine suggests that getting too many daily calories from protein could raise cardiovascular disease risk. The study was published in Nature Metabolism in February.

Generally, registered dietitians say paying attention to how diet can affect your heart is important. "Heart disease and dietary intake are closely linked, and it is of huge benefit to study this interaction, as heart disease is the leading cause of death in Western countries," says Maddie Pasquariello, MS, RDN. 

What does this study add? Experts share insights on what it tells us, why people shouldn't panic and heart-healthy ways to consume protein. 

Related: The One Diet That Will Actually Lower Your Heart Attack Risk, According to Cardiologists

Heart Disease Risk and Protein Consumption

TL;DR: "This study indicates that high amounts of protein—greater than 25 grams per meal or 22% of total calories—can increase mTOR activation and can increase atherosclerosis in male mice," explains Julia Zumpano, RDN, LD, of the Department of Preventive Cardiology at Cleveland Clinic.

Atherosclerosis is a buildup of fat and cholesterol along the artery walls that can increase a person's risk for heart attack, stroke and blood clots. mTOR is a protein.

"[The mTORC1] pathway is thought to be responsible for cell growth and, when it is hyper-activated, it can contribute to age-related pathologies, including heart conditions like atherosclerosis," Pasquariello explains.

Now, back up a second. "It's important to first provide a very vital caveat," Pasquariello explains. "While one new study can certainly contribute to our knowledge on a given topic and illuminate future research directions, like any other new piece of intel, this new research in Nature Metabolism is just that—a small blip in our understanding of a much larger, long-running conversation."

In other words, don't hit the panic button if you've got a high-protein diet.

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"Researchers undertook two studies, comprised of 14 and 9 participants, respectively," Pasquariello says. "Why is this important? These are extremely small studies, and results should be interpreted with even more of a grain of salt."

The first study compared liquid meals in which 50% of the calories came from protein and one in which 10% of the calories came from protein, which would affect the mTORC1. Pasquariello says that researchers were particularly interested in leucine.

"Leucine is an essential amino acid found in various protein-rich foods such as meat, poultry, fish, dairy and legumes," says Michelle Routhenstein, MS, RD, CDCES, CDN, a preventive cardiology dietitian at EntirelyNourished.com.

The result? "They found that ingesting the 'very-high-protein' meal—the one where 50% of total calories came from protein—but not the 'low-protein meal,' increased mTORC1 signaling in the three hours following mealtime, primarily due, they claim, to the effect of leucine," Pasquariello says.

In the second study, the mice consumed liquid meals containing 15% or 22% of calories from protein. Pasquariello says researchers took a similar approach in the first study. "[They were] primarily evaluating the effect of the change in protein intake on the signaling of the mTORC1 pathway," Pasquariello explains.

The outcomes were similar. "From this study, they concluded that the threshold for potential detrimental effects of leucine on the mTORC1 pathway may be even lower than what study No. 1 implied and may be seen with a percentage of total calories from protein closer to 22%, a threshold they had theorized from earlier rodent models of the pathway," Pasquariello shares. 

Related: If You Want to Lower Your Heart Attack Risk, Cardiologists Say You Should Do This One Thing Every Day

OK—but What Does the Research Actually Tell Us About Protein and Heart Disease?

The information above may feel dense, even in lay terms. What does it all mean? Should you consume fewer than 22% of your daily calories from protein? Experts say it's way too soon to tell, and the study design has them highlighting several caveats. However, the study has importance. 

"Consuming excessive amounts of protein, particularly with high levels of leucine, may increase heart health risks due to the potential for mTOR activation, leading to inflammation and atherosclerosis development," Routhenstein says.

This point is vital given the confusion about protein, partly prompted by social media.

"Unfortunately, dietary guidance around protein intake has become very confusing and often misleading, thanks in large part to the proliferation of misinformation on social media," Pasquariello says. "Like everything in nutrition, the answer isn't a one-size-fits-all approach, and, just because your gym buddy has ratcheted up their protein intake to 200 grams per day, doesn't mean it's safe [or] effective, or that you should do it, too."

However, Pasquariello emphasizes that the small sample size and the fact that mice (not humans) were studied are important to note. Zumpano agrees.

"This study is preliminary and is done in mice," Zumpano says. "The human arm of the study was very small and did not provide significant data to conclude that increased protein intake can lead to atherosclerosis in humans." 

Related: The One Diet You Should Try ASAP if You Want to Lose Weight and Lower Your Cholesterol

Heart-Healthy Protein Intake

Dietitians don't want the headlines to scare people off from consuming protein."I feel that a moderate amount of protein from a combination of lean animal and plant sources is not harmful to heart health," Zumpano says.

In fact, protein serves a vital function in our overall health.

"Protein is essential for various bodily functions, including muscle repair, hormone production and immune function," Routhenstein says. "It is crucial."

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It's complicated to give a hard-and-fast number on how much protein a person should consume. “Protein needs vary based on age, gender, activity level and muscle mass," Zumpano explains. 

The type also matters. "It's generally a good rule of thumb to get as much of your protein as possible from foods like beans, peas, lentils and nuts, as well as omega-3 fatty acids [like] fish and shellfish, according to the American Heart Association, while keeping sources like red meat, fatty meats and processed deli meat to a minimum," Pasquariello says.

As for those TikTok-famous supplements? "I do not feel protein supplements are necessary unless protein needs are not being met by food intake," Zumpano says.

A dietitian can help you cut through the noise and determine how much protein is best for you.

Next up: The One Thing You Should Never, Ever Do If You Have Insulin Resistance and Want to Lose Weight

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