Getting your protein from plants instead of animals could prolong your life, a new study suggests.

Researchers prospectively followed 70,696 Japanese men and women, average age 55, for an average of 18 years. All had completed detailed health and diet questionnaires, and none had a history of cancer or cardiovascular disease at the start. There were 12,381 deaths over the period.

After adjusting for age, sex, smoking, fat intake, body mass index, physical activity and other health and behavioral characteristics, they found that compared with the one-fifth of the group who ate the least plant protein, the fifth who consumed the most had a 27 percent lower rate of cardiovascular death, a 28 percent lower rate of death from heart disease and a 28 percent lower rate of stroke.

Substituting plant protein for red or processed meat was associated with lower mortality, though the researchers found no correlation between the amount of animal protein intake and mortality when considered alone. This is probably because most animal protein in the Japanese diet comes from fish, not red meat.

Still, those who ate the most plant protein, which is abundant in such foods as spinach, broccoli and legumes like lentils, soy beans and chickpeas, had a 13 percent lower all-cause mortality rate than those who ate the least.