Scientific evidence shows that some dietary supplements are beneficial for overall health and for managing some health conditions. For example, calcium and vitamin D are important for keeping bones strong and reducing bone loss; folic acid decreases the risk of certain birth defects; and omega-3 fatty acids from fish oils might help some people with heart disease. Other supplements need more study to determine their value. The U.S. Food and Drug Administration (FDA) does not determine whether dietary supplements are effective before they are marketed.

Fats: Can they be healthful? Fats get a bad reputation but are necessary for good health. Different sources of food provide different types and amounts of fat. This article looks at which fats are actually good for you and how to go about replacing unhealthy fats with fats that are good for you, as well as the relationship between fat and weight. Read now
A study of dietary supplements sold between 2007 and 2016 identified 776 that contained unlisted pharmaceutical drugs, many of which could interact with other medications and lead to hospitalization.[79] 86% of the adulterated supplements were marketed for weight loss and sexual performance, with many containing prescription erectile dysfunction medication. Muscle building supplements were contaminated with anabolic steroids, and multiple products contained antidepressants and antihistamines. Despite these findings, fewer than half of the adulterated supplements were recalled.[79]
Protein-containing supplements, either ready-to-drink or as powders to be mixed into water, are marketed as aids to people recovering from illness or injury, those hoping to thwart the sarcopenia of old age,[20][21] to athletes who believe that strenuous physical activity increases protein requirements,[22] to people hoping to lose weight while minimizing muscle loss, i.e., conducting a protein-sparing modified fast,[23] and to people who want to increase muscle size for performance and appearance. Whey protein is a popular ingredient,[21][24][25] but products may also incorporate casein, soy, pea, hemp or rice protein.
Dietary supplements are complex products. The FDA has established good manufacturing practices (GMPs) for dietary supplements to help ensure their identity, purity, strength, and composition. These GMPs are designed to prevent the inclusion of the wrong ingredient, the addition of too much or too little of an ingredient, the possibility of contamination, and the improper packaging and labeling of a product. The FDA periodically inspects facilities that manufacture dietary supplements.