Fat. Monounsaturated fats are healthful for both men and women; olive oil is a good source. The omega-3 fatty acids found in fish are also good for both sexes. But a vegetable-based omega-3 called alpha-linolenic acid (ALA), found in canola and flaxseed oils, may be a problem for men. ALA is good for the heart, but some studies suggest it may increase the risk of prostate cancer. For men with heart risks, ALA may be a good choice—but men with more reason to worry about prostate cancer should get their omega-3s from fish and their vegetable fats from olive oil.
Alcohol. In both men and women, low alcohol intake appears to reduce the risk of heart attacks and certain strokes, while larger amounts increase the risk of many ills. But while drinking responsibly doesn't seem to cause any health problems for average men, even low doses of alcohol may increase a woman's risk of breast cancer.
Calcium. A high-calcium diet may protect women against osteoporosis. There's far less evidence that dietary calcium has the same benefit for men; in fact, large amounts may increase their risk of prostate cancer. The solution is moderation. The vitamin D in a daily multivitamin may also help offset the possible risks.
Iron. Men need less than women and should avoid excess iron. In the presence of an abnormal gene, it can lead to harmful deposits in various organs.
Despite these points, men and women's overall nutritional needs are more similar than different, reports Harvard Men's Health Watch.