The idea that increasing protein in the diet is a proven step to health is widespread. If you abstain from meat, have you not heard the question “where do you get your protein” over and over?
What Is Protein?
Proteins are formed from amino acids. One group of amino acids contain sulfur and include methionine (Met) and cysteine. Rather than being a benefit to increase these amino acids in the diet, researchers have been examining the impact of restricting sulfur amino acids.
In one early study involving rats, an 80 percent restriction in Met increased lifespan in animals by between 42 and 44 percent. In another study in yeast, an extended lifespan with Met restricted diets was also shown. Does this data apply to humans? In a review of studies, sulfur amino acid restriction consistently demonstrated a range of beneficial effects including enhanced lifespan. In a study last year at Duke University, scientists showed that dietary restriction of sulfur amino acids influenced cancer outcomes. Foods that are high in sulfur amino acids are almost exclusively animal based foods. This suggests that a plant diet is an advantage by providing adequate, but not excessive, sulfur-based proteins.
But what about heart disease and protein intake?
Sulfur Protein Intake and Heart Disease
Scientists at Penn State University were interested in whether the intake of sulfur amino acids related to heart disease. They examined data from 11,576 adults in the NHANES III study from 1988-1994 with follow-up. They found that the average intake of these sulfur amino acids like methionine and cysteine was 2.5 higher than required. Furthermore, the amount of sulfur amino acids ingested was associated with risk scores of heart disease and cardiometabolic disease. This was independent of traditional risk factors like cholesterol, glucose, insulin, and uric acid.
The authors concluded that lower intake of these amino acids correlated with a lower risk of heart disease and that “meats and other high-protein foods are generally higher in sulfur amino acid content. People who eat lots of plant-based products like fruits and vegetables will consume lower amounts. These results support some of the beneficial health effects observed in those who eat vegan or other plant-based diets. ”
Foods highest in methionine, for example, are beef, chicken, turkey, pork and fish. Fruits, vegetable, legumes, and grains often have 75-90 percent less methionine. Is their other data suggesting protein restriction for health outcomes? When researchers from the University of Southern California examined the impact of protein intake on overall mortality and cancer rates, lower protein diets were associated with the best outcomes, particularly in those under age 65.
There are many reasons to adopt a diet of plant foods that extend from health, to the environment, to animal rights. The new data from Penn State University provide more support from a health perspective to ditch the meats and eat whole plant foods. So, the next time you get asked “where do you get your protein?” you can answer with kindness, “from plants that have just the right amount of sulfur amino acids , thank you.”
Dr. Joel Kahn is Professor of Cardiology, Summa cum Laude grad, Kahn Center for Longevity and GreenSpace & Go, author, “The Plant Based Solution.” www.drjoelkahn.com @drjkahn.