Wish your skin looked younger? Aging can change skin's appearance as early as your 30th birthday. According to leading dermatologists, younger skin starts with the nutrients that reach it from inside the body. The skin is the body's largest organ, so diet affects how you visibly age. Take 1,000 IUs per day of vitamin D supplement and eat plenty of omega-3 and omega-6 fatty acids. Ideally they should come from natural sources, including olive oil, ground flaxseed, and fish such as salmon.