Kris Clark, PhD, RD, sports nutrition director at Penn State University, says she very carefully uses select sports supplements with collegiate athletes: "I rely on the major nutrients in food, timing of meals and fluids to enhance athletic performance, and in general I discourage dietary supplements, other than the use of sport shakes, bars, and gels after practice or events for muscle cell recovery."
The tiny gender differences in minerals other than calcium and iron depend on body size. But while the dietary requirements for selenium fit this rule, men may benefit from supplements of about 200 micrograms a day, a level about four times above the RDA. That's because both a clinical trial and an observational study suggest that selenium may reduce the risk of prostate cancer. It's far from proven, but it's something for men to consider.
Eat healthy fats. According to the American Heart Association, women should get at least five to 10 percent of total daily calories from omega-6 fatty acids (equal to 12 to 20 grams), and between 0.5 and 3 grams of omega-3 fatty acids, depending on individual risk for heart disease. Good sources of omega-6 fatty acids include sunflower, safflower, corn, cottonseed and soybean oils. And good sources of omega-3 fatty acids include fatty fish, tofu and other forms of soybeans, canola, walnuts, flaxseed, and their oils. Talk with your health care professional about how much of these beneficial oils you should be getting, how you can best incorporate them into your diet and whether or not you should be taking them in supplement form.
Consult your health care professional. Women of childbearing age may want to consider taking folic acid supplements to reduce the risk of having a pregnancy affected with neural tube defects. Many women and teenage girls don't get enough calcium or vitamin D, both of which are critical to healthy bones and avoiding osteoporosis. Some people with diabetes appear to benefit from chromium. Vegetarians, especially vegans, may want to consider supplements to obtain nutrients they aren't getting from animal products.
Access to correct information about food and essential nutrients, including knowledge about the importance of food for health is a fundamental human right. Such information should not only provide a summary of the nutrient content of food, but in our opinion should also explain how dietary supplements can counteract deficiencies and prevent and reverse disease caused by nutrient deficiencies. We should be free to purchase quality-controlled supplements of essential nutrients and to use them to counteract aging and damage from stress as part of a long-term health plan. The right to reject recommendations by doctors for symptomatic treatment with synthetic, some times life-threatening, drugs to alleviate symptoms should be included. [48,49]
d minerals to fiber and herbal remedies, these supplements are not regulated in the same way as either food or medicine. Some of them are backed by solid research, others are folk remedies or proprietary cures. If your diet does not include enough of certain vitamins or minerals, a supplement may be a good idea. Natural treatment for conditions like constipation may be effective. But because these substances are unregulated, it is always a good idea to educate yourself about the products and to use common sense when taking them. This is even more true if you are pregnant or taking a medicine that may be affected by supplements.
Cholesterol. Cholesterol is found in foods made from animals, such as bacon, whole milk, cheese made from whole milk, ice cream, full-fat frozen yogurt, and eggs. Fruits and vegetables do not contain cholesterol. Eggs are a major source of dietary cholesterol for Americans, but studies show that eating one egg a day does not increase the risk for heart disease in healthy people.2 You should eat less than 300 milligrams of cholesterol per day. Check the Nutrition Facts label for cholesterol. Foods with 20% or more of the “Daily Value” of cholesterol are high in cholesterol.
Nutritional supplements are exactly that, supplements to a healthy, nutritious diet. One should not take nutritional supplements in the hope that they will make up for a poor diet and lack of exercise, they will not! There are some nutritional supplements including some vitamins and minerals, as well as other nutrients/cofactors that one can use in conjunction with a healthy diet to promote optimal health. For example, to consume the amount of vitamin E that has been shown to protect the body against free radical damage, one would have to consume a very significant amount of fat calories as vitamin E is found in foods that are high in fat such as vegetable oils, nuts and seeds. it makes sense to take a supplement of vitamin E rather than consuming lots of fat. The same goes for vitamin D. It's very difficult to get vitamin D in your diet as it isn't found in many foods and studies show that most people do not get enough vitamin D.
As with all dietary supplements, in the United States inappropriate label health claims such as preventing or treating disease are opposed by the FDA and deceptive advertisements by the Federal Trade Commission. Probiotic foods and dietary supplements are allowed to make claims using Structure:Function vocabulary as long as human trial evidence is adequate. In 2005, the FDA issued a Warning Letter to UAS Laboratories for disease treatment claims (colds, flu, ulcers, elevated blood cholesterol, colon cancer...). The company revised label and website content and continued to sell the product. In 2011 the company was found to have resumed the label and website claims, and the FDA seized product and stopped production. In 2010 a FTC action was brought against a probiotic food company for exaggerated health claims, resulting in a multimillion-dollar fine and revisions to future advertising. In the European Union a more restrictive approach has been taken by the EFSA. All proposed health claims were rejected on the grounds that the science was not sufficient, and no health claims are permitted. Foods with live microorganisms (yogurt, kefir) can be sold, but without claims.
Don't take dramatic steps alone. You need to work closely with an experienced health care professional to lose weight, particularly if you have other medical problems, plan to lose more than 15 to 20 pounds or take medication on a regular basis. An initial checkup can identify conditions that might be affected by dieting and weight loss. Make sure you find out how much experience your health care professional has dealing with nutrition. It's not always well covered in medical schools. You may want to talk to a registered dietitian before embarking on a diet.
Vitamin C protects the brain and nervous system from damage caused by stress because the synthesis and maintenance of chemical neurotransmitters such as adrenaline and noradrenaline requires adequate levels of vitamin C.  Vitamin C is also needed to repair collagen which is essential for skin, blood vessels, bones and joints, and muscles. When these are damaged by physical stress, extra vitamin C is necessary. A controlled trial of 91 adults who experienced increased anxiety and stress 2-3 months after an earthquake in New Zealand in 2011 was divided into three groups, two were given a broad spectrum supplement of micronutrients in low or higher doses.  The supplements were found to alleviate the experience of stress, with the biggest dose having the biggest effect.
There is more than one way to eat healthfully and everyone has their own eating style. Make healthier choices that reflect your preferences, culture, traditions, and budget. Choose fruits, vegetables, grains, dairy, and protein foods to get the most nutrition and meet your personal calorie needs. Aim for a variety of foods and beverages from each food group and limit saturated fat, sodium, and added sugars.
For example, while increased consumption of fruits and vegetables are related to decreases in mortality, cardiovascular diseases and cancers, supplementation with key factors found in fruits and vegetable, like antioxidants, vitamins, or minerals, do not help and some have been found to be harmful in some cases. In general as of 2016, robust clinical data is lacking, that shows that any kind of dietary supplementation does more good than harm for people who are healthy and eating a reasonable diet but there is clear data showing that dietary pattern and lifestyle choices are associated with health outcomes.