Fasting. Time-restricted eating. Eating for five days, then fasting for two. Lately, it appears everyone is interested in some sort of calorie-restricted diet to better their chances for a longer life with fewer chronic diseases.
But what if you could get the same longevity benefits without having to eat less?
New research shows limiting protein-rich foods that naturally contain high levels of sulfur amino acids, such as meats, dairy, nuts, and soy, may reduce the risk for cardiovascular disease. If future research bears that out, it may be another stepping stone to better health and longer life.
"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 in a statement.
"This study provides the first epidemiologic evidence that excessive dietary intake of sulfur amino acids may be related to chronic disease outcomes in humans," Richie added.
In the search for another path to the fountain of youth, researchers have been exploring the role of methionine and cysteine, two of the body's nine essential amino acids that contain sulfur.
In test tubes and animal studies, it appears restricting foods high in dietary sulfur amino acids delayed aging and increased lifespans. In one early study of rats, limiting methionine by 80% increased the rats' lifespans by an average of 43%. Research since then has duplicated that benefit.
But translating that amazing result to humans would be tricky. Sulfur amino acids play key roles in growth, so restricting those foods in rats created stunted, smaller creatures that happened to live longer with fewer diseases.
Obviously not a good scenario for people, even if the longevity results crossed species. Often what works with lab animals doesn't work in humans.
However, in a 2018 analysis of research, Richie and his team found when diets of fully-grown animals were restricted, adults got the same health benefits without having to worry about retarding growth.
That lead to the current study, published Monday in the journal Lancet EClinical Medicine, which examined the diets and blood biomarkers of more than 11,000 participants collected by a nutritional health survey of Americans done by the Centers for Disease Control and Prevention.
One finding: Americans appear to be eating 2.5 times the amount of sulfur amino acid than the estimated nutritional requirement, said co-author Xiang Gao, director of the nutritional epidemiology lab at Penn State University.
"Many people in the United States consume a diet rich in meat and dairy products," said Gao in a statement."Therefore, it is not surprising that many are surpassing the average requirement when considering these foods contain higher amounts of sulfur amino acids."
In addition, higher sulfur amino acid intake was linked to a higher cardiovascular disease risk score. That's not surprising, considering a high intake of fatty foods such as red meat, dairy, and other fats are known risk factors for heart disease.
Does all this point to a new pathway to longer life or just reinforce what we already know about our eating habits? This study was observational, relied on people reporting their eating habits and captured only one moment in time. And it did not analyze weight, though other studies have confirmed a link between a plant-based diet and weight loss. A lot more work needs to be done.
"People who eat lots of plant-based products like fruits and vegetables will consume lower amounts of sulfur amino acids," said Zhen Dong, lead author on the study and a graduate of Penn State College of Medicine "These results support some of the beneficial health effects observed in those who eat vegan or other plant-based diets."