For starters, American men were already consuming that much protein (around 100 grams per day) despite lower federal recommendations. In fact, even the benefits of boosting our protein intake as we age are coming under scrutiny in a new review published in the journal Cell Press Blue. They found that decreasing protein intake is associated with improved metabolism, less cellular damage, and healthier aging, and identified the molecular mechanisms that may be responsible. One key factor, a hormone produced by the liver called fibroblast growth factor 21 (FGF21), ramps up when protein intake declines. “We probably need to personalize protein recommendations based not just on age, but also on how physically active people are.”