Red meat could be bad for the heart

(CNN) - Need more reasons to start trying meat-free Mondays? How about going full vegetarian?

According to the results of two preliminary studies, eating more protein from plant sources or dairy while reducing how much red meat you consume could help you live longer.

Plant proteins include soybeans (edamame), chickpeas, lentils and other legumes, tofu, tempeh, nuts, seeds and whole grains like quinoa. Some vegetables, like broccoli, also contain higher levels of protein.

In the first study, which tracked more than 37,000 Americans with an average age of 50, those who ate the most plant protein were 27% less likely to die of any cause and 29% less likely to die of coronary heart disease when compared to people who ate the least amount of plant protein.

"It isn't enough just to avoid red meat -- it's also about what you choose to eat in place of red meat," Dr. Zhilei Shan, lead study author and postdoctoral research fellow at the Harvard T.H. Chan School of Public Health, said in a news release.

Shan pointed out that nuts, seeds, legumes and whole grains contain more than just protein. They include healthy fats, vitamins, minerals and antioxidant "phytochemicals," which he said "have been associated with lower risk of chronic diseases such as diabetes, cardiovascular disease and some cancers."