Protein is an important part of any diet, and growing kids need to make sure they get enough. But adults — they tend to get plenty. Longo, who worked on the new human study, recommends that adults replace some animal proteins in their diets with more plant-based ones, such as those proteins found in beans and nuts. After all, he argues, “If we’re wrong, there’s no negative side effect.” However, he points out, “If we’re right, it means a reduction in cancer and diabetes.”