There is already evidence that adequate selenium in the diet may be protective against cancer, and perhaps have an impact on male fertility.

BBC: Poor diet 'boosts virus power'

The new study, published online Monday by the Journal of the American College of Cardiology, is consistent with other findings of the protective benefit of the Mediterranean diet.

WSJ: Study Finds More Benefits From the Mediterranean Diet

Researchers don't know why a plant-based diet seems to have a protective effect, but one likely reason is the nutrient profile of vegetarian diets, which tend to be higher in fiber and lower in saturated fat.

WSJ: Vegetarians Live Longer Than Meat-Eaters, Study Finds

The paper suggested that a diet rich in fruit and vegetables may be helpful because of the protective effects of antioxidants and vitamin C.

BBC: Asthma risk 'linked to burgers'