Amino acids are the building blocks of proteins, and sulfur amino acids are a subcategory which plays various roles in metabolism and health.
“For decades it has been understood that diets restricting sulfur amino acids were beneficial for longevity in animals,” said John Richie, a professor of public health sciences at Penn State College of Medicine. “This study provides the first epidemiologic evidence that excessive dietary intake of sulfur amino acids may be related to chronic disease outcomes in humans.”
For the Penn State study, more than 11,000 participants from a national study were examined for their diet habits and blood biomarkers. Based on their bloodwork, researchers found that participants who ate foods containing fewer sulfur amino acids and consumed lower protein diets tended to have a decreased risk for cardiometabolic disease.
The team then evaluated data from the Third National Examination and Nutritional Health Survey. They created a composite cardiometabolic disease risk score based on the levels of certain biomarkers in participants’ blood after a 10–16 hour fast including cholesterol, triglycerides, insulin, and glucose.
“These biomarkers are indicative of an individual’s risk for disease, just as high cholesterol levels are a risk factor for cardiovascular disease,” Richie said. “Many of these levels can be impacted by a person’s longer-term dietary habits leading up to the test.”
Participants were excluded from the study if they reported dietary intake of sulfur amino acids below the estimated average requirement of 15 mg/kg/day recommended by the Food and Nutrition Board of the National Academy of Medicine. Those with congestive heart failure, heart attack, or a reported change in diet due to a heart disease diagnosis were also omitted.
After examining the participant’s diet, the researchers found that the average sulfur amino acid intake was almost two and a half times higher than the estimated average requirement. Xiang Gao, co-author of the study, suggested this may be due to trends in the average diet of a person living in the United States.
“Many people in the United States consume a diet rich in meat and dairy products and the estimated average requirement is only expected to meet the needs of half of healthy individuals,” Gao said. “Therefore, it is not surprising that many are surpassing the average requirement when considering these foods contain higher amounts of sulfur amino acids.”
Although this study only evaluated dietary intake and cardiometabolic disease risk factors at one point in time, the association between increased sulfur amino acid intake and risk for cardiometabolic disease was strong. This research opens the door for longer, more detailed studies to help understand the association between plant-based diets and cardiovascular disease.