High-protein diets are becoming more and more popular as a method to both increase muscle mass and lose weight. Now however, new research is showing that excessive consumption of protein-rich foods may damage cardiovascular health due to their high presence of certain amino acids.
Two sulfur amino acids are present in protein-rich food: methionine, and essential amino acid, and cysteine, a semi-essential amino acid. Although these aids are essential for the body to function, as with many other nutrients, when present in excessive quantities, they may be harmful.
For their study, researchers from Penn State analyzed health and dietary information from 11,576 people taken by the Centers for Disease Control and Prevention. In particular, they examined levels of tell-tale biomarkers, such as cholesterol, triglycerides, glucose and insulin in each participant's blood after fasting for 10-16 hours. Alongside this, they also made calculations on each participant's nutrition intake from analyzing their diets.
In the end, after controlling results for body weight, the researchers found that on average, each participant had almost 2.5 times the estimated average requirement of 15 milligrams per kilogram of body weight per day. Given the high levels of dairy and meat products found in the average American diet, this did not come as a surprise.
However, alongside this, they also found that those with higher sulfur amino acid intake also tended to have higher composite cardiometabolic risk scores. The correlations remained the same even after accounting for factors such as age, biological sex, and history of health conditions including hyertension and diabetes.
Although suggestive that diets with lower quantities of sulfur amino acids are therefore more beneficial for heart health, such as those richer in plant-based products, the researchers caution that their findings are so far only observational. Thus, to confirm their conclusions, further research is needed, preferably via a longitudinal study.
Nevertheless, co-author of the study, Professor John Richie said, “For decades, it has been understood that diets restricting sulfur amino acids were beneficial for longevity in animals. This study provides the first epidemiologic evidence that excessive dietary intake of sulfur amino acids may be related to chronic disease outcomes in humans.”