India, Nov. 19 -- A new analysis out of Penn State is pushing back on the long-standing belief that beef automatically spells trouble for the heart. The research team, writing in the Journal of the American Heart Association, tracked how different diets affected trimethylamine N-oxide - TMAO - a blood marker often linked to cardiovascular disease.

Their conclusion was more measured than expected. When participants ate modest portions of lean beef within a Mediterranean-style diet, TMAO levels did not climb.

TMAO forms when the body breaks down certain animal foods, beef included, so the researchers wanted to see exactly how portion size and diet quality changed the equation.

Kristina Petersen, who teaches nutritional sciences at Penn S...