Some bodybuilders and athletes turn to dietary supplements to help them increase muscle size and definition. However, many bodybuilding products marketed as dietary supplements have been found to contain other ingredients that can be harmful. Use caution and talk with your health care provider before you begin taking any supplement to gain strength or muscle size.
- Multivitamin and mineral supplements are unnecessary for athletes or other physically active people who eat a well-balanced diet and enough calories. The safety of supplements used for bodybuilding remains an issue of concern (see Safety section below).
- There is no scientific evidence that other dietary supplements, such as choline, methoxyisoflavone, zinc/magnesium aspartate, nitric oxide precursors, and chromium, are effective for building strength and muscle mass.
- Evidence suggests that creatine, a popular dietary supplement, may enhance the effects of vigorous exercise on strength, muscle mass, and endurance, but it may also cause fluid weight gain, nausea, cramping, and diarrhea.
- Many bodybuilding products marketed as dietary supplements have been found to be deceptively labeled and to contain hidden ingredients that can be harmful, such as anabolic steroids, compounds chemically similar to them, or other substances that do not qualify as dietary ingredients.
- In April 2013, the U.S. Food and Drug Administration issued a warning to consumers to avoid products containing the stimulant dimethylamylamine (DMAA). DMAA can elevate blood pressure and lead to other problems, such as heart attack.
- Evidence suggests that creatine (an amino acid produced by the body) supplements may be safe for short-term use in healthy adults, but the American College of Sports Medicine recommends against anyone younger than age 18 using it to enhance athletic performance.
- Some dietary supplements may have side effects and some may interact with drugs or other supplements. Some vitamins and minerals are harmful at high doses. Talk with your health care provider before using a dietary supplement to increase muscle size and strength.