Supplements are ingested and come in many forms, such as tablets, capsules, softgels, powders, sticks, gummies, and liquids. Minerals like calcium, magnesium, and iron are often found in supplements. While they can help promote health, they are not intended to be treatments or prevent any type of disease. Therefore, the “placebo” group of the RCTs of micronutrient supplements is not a true placebo or “unexposed” group, unlike the placebo group in the RCTs of drugs. Examples of supplements include berberine, fish oil, echinacea, chromium, magnesium, ginkgo, zinc, cayenne, milk thistle and valerian.
Some people believe that vitamins and supplements are inherently different. For instance, studies on micronutrient supplementation compare low intake (from diet) with higher intake (from supplements) in subjects who consume these micronutrients throughout their lives; on the contrary, pharmacological trials compare the absence of the drug with its presence in subjects who have not been exposed to this drug before. The Dietary Guidelines for Americans state that your nutritional needs should be met primarily through diet. However, you can supplement them with vitamins if your needs cannot be met by food alone. Postmenopausal men and women are not at risk of iron deficiency; too much iron from diet and supplements can have adverse effects.
Some studies have shown that users of multivitamin supplements are more likely to follow a healthier diet or to rate their health as excellent or very good. This suggests that those who do not take multivitamin supplements may benefit most from supplementation. In addition, since excess preformed vitamin A (retinol) during pregnancy is known to cause birth defects and since several foods in the U. S. are fortified with retinol, the LPI recommends that pregnant women avoid taking a multivitamin or prenatal supplement that contains more than 5000 IU (1500 μg) of vitamin A in the form of retinol. While there is no consensus that the use of multivitamin supplements by the general population benefits general health or prevents chronic diseases, these supplements are generally considered safe for healthy people.
If you're not sure how to eat a healthier diet or if you should take a supplement, consider talking to a healthcare provider. Studies that measure micronutrient status in the blood and correlate it with health outcomes are more reliable than those that measure the use of supplements using questionnaires or recovery methods. As part of its Rx for Health program, the Linus Pauling Institute recommends a daily vitamin M supplement as nutritional insurance to meet micronutrient needs.