Dr. Ralph Sacco, a University of Miami neurologist who also is a former heart association president, agreed.
"Sometimes when you eat nuts you eat less of something else like potato chips," so the benefit may come from avoiding an unhealthy food, Sacco said.
The Harvard group has long been known for solid science on diets. Its findings build on a major study earlier this year — a rigorous experiment that found a Mediterranean-style diet supplemented with nuts cuts the chance of heart-related problems, especially strokes, in older people at high risk of them.
Many previous studies tie nut consumption to lower risks of heart disease, diabetes, colon cancer and other maladies.
In 2003, the Food and Drug Administration said a fistful of nuts a day as part of a low-fat diet may reduce the risk of heart disease. The heart association recommends four servings of unsalted, unoiled nuts a week and warns against eating too many, since they are dense in calories.