An excessive intake of a certain form of amino acid— found in protein-rich foods — is associated with a higher cardiometabolic risk according to a new study evaluating the data of thousands of people.
Most people follow high-protein diets, which can help with weight loss and build muscle mass. Nonetheless, researchers are increasingly beginning to question whether protein-rich foods offer adequate benefits to outweigh the potential risks.
For the most part, numerous recent studies have suggested that high protein foods can affect cardiovascular system and heart health.
For instance, a review of animal models reported by nccmed last week found diets high in protein may be directly responsible for cardiovascular problems, such as atherosclerosis.
Now, fast on its heels, a new human study highlights a correlation between eating foods with a high amino acid content of sulfur— typically high protein foods— and an increased risk of cardiometabolism.
The study— whose findings appear in EClinicalMedicine— comes from State University in State College, Pennsylvania (Penn).
Proteins are made up of tiny compounds called amino acids which vary in components. Others contain sulfur element atoms which give them the name: sulfur amino acids.
Cardiometabolic risk and diet
Two amino acids of sulfur present in foods rich in proteins. These are methionine, an essential amino acid, and the semi-essential amino acid, cysteine.
These amino acids are needed by the human body to function properly, and must be obtained from a food source. The body can not synthesize essential amino acids, and the semi-essential ones can not be made enough.
Though, as with many other nutrients, amino acids can end up doing more harm than good, if they are present in large amounts.
This was discovered by Penn State researchers as they looked at the diets and health status of 11,576 individuals whose data they obtained through the third National Health and Nutrition Examination Survey (NHANES III) administered by the Centers for Disease Control and Prevention (CDC).
The researchers developed a composite risk score for cardiometabolic disease that measured the risk of each participant having cardiometabolic complications, such as heart disease, stroke, and diabetes.
To do so, they tested the rates of tell-tale biomarkers— including cholesterol, triglycerides, glucose (sugar), and insulin — in the blood of the participants after a 10–16 hour pace.
“Such biomarkers reflect an individual’s risk of disease, just as high cholesterol levels are a risk factor for cardiovascular disease,” explains Prof. John Richie, co-author of the study.
“Many of those levels can be influenced by the long-term dietary habits of a person leading up to the test,” adds Prof. Richie.
The researchers also analyzed details on dietary habits of the participants, which included estimates on nutrient intake. Any individuals who reported having an excessively low intake of sulfur amino acids were removed from research.
‘First epidemiologic evidence’
The final analysis of the team, which accounted for body weight measurements, showed that the participants had an average intake of sulfur amino acids which was approximately 2.5 times higher than the estimated average body weight requirement of 15 milligrams per kilogram per day.
“Few people in the U.S. eat a diet high in meat and dairy products and the estimated average demand is only expected to meet the needs of half of healthy people,” says co-author of the study, Xiang Gao.
“It’s not shocking, therefore, that many surpass the average requirement when considering such foods contain higher amounts of amino acid sulfur,” says Gao.
In addition, the investigators found that participants with higher intakes of sulfur amino acid also tended to have higher cardiometabolic risk scores for composites.
Even after the researchers accounted for confounding factors like age, biological sex, and a history of health conditions such as hypertension and diabetes, this correlation remains in place.
As for the sulfur amino acid source, the team said they were present in almost all foods, except grains, fruits, and vegetables.
“Meats and other high protein products in the sulfur amino acid content are generally higher,” states lead author Zhen Dong, Ph.D.
“People who eat plenty of plant-based foods such as fruit and vegetables will consume lower concentrations of amino acids in sulphur. These findings reflect some of the positive effects on health found in those consuming vegan or other plant-based diets,” adds Dong.
The researchers caution that the current findings are, so far, only observational, pointing to an association rather than verifying causality.
“A longitudinal study will allow us to examine whether people who eat this way end up contracting the diseases for which these biomarkers suggest a risk,” Prof. Richie says.
However, he stresses that the recent study indicates that researchers should pay more attention to the potential risks of dietary amino acids.
“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.”
– Prof. John Richie
