Many Americans use dietary supplements, including vitamins, minerals, herbs and botanicals, amino acids, and other substances. Though many supplements are promoted as a cure for common illnesses, or prevent disease, such as heart disease, large-scale studies have not shown this to be true.

In fact, taking megadoses of fat-soluble vitamins (A, D, E and K) can cause problems and high doses of calcium may result in vascular or soft tissue calcification, kidney stones and interfere with certain prescription medications.

Supplement Benefits

Vitamins, minerals, herbs and botanicals, amino acids, and probiotics are just a few of the dietary supplements that are available. Supplements come in many forms, from capsules to gummies and liquids. They are often touted as easy and efficient ways to meet nutritional needs.

Scientific investigations of supplements begin with observational studies that compare the health outcomes of people who take a particular supplement with those who don’t. This type of research is a valuable first step, but it’s not always conclusive. A better approach is to conduct randomized clinical trials in which volunteers are assigned by chance to take either the supplement or a placebo and then followed over time to see if the supplement has an effect.

Registered dietitians generally recommend food before taking any supplements, but if you do choose to take a supplement, look for one that has been third-party tested. The National Sanitation Foundation (NSF) offers a certification for supplements that is searchable on their website, as does the United States Pharmacopeia (USP). These tests can help ensure that the supplement is free of contaminants and that the amount of active ingredients is consistent from batch to batch. It's also a good idea to discuss any supplements you are considering with your healthcare team, especially if you have an underlying health condition or are taking medications.

Expert Advice

Vitamins are organic compounds that our bodies use in very small amounts for a variety of metabolic processes. Our best sources of vitamins are the healthy unprocessed foods we eat, such as whole grains, fruits, vegetables, and meats. If your diet is adequate, you may not need vitamin supplements, but talk to your doctor. Those who have specific vitamin deficiency needs might benefit from multivitamins or high dose supplements of individual nutrients such as vitamin D, folate, vitamin A, and vitamin E. However, large doses of fat-soluble vitamins (vitamins A, D, and E) can build up in your body to toxic levels, so it's important to get your vitamins from a well-balanced diet or under your doctor's supervision.

Dietary supplements are not regulated by the FDA in the same way as drugs, so there is little oversight to help you discern what is effective and safe. However, some independent organizations offer certifications to verify the quality of dietary supplements. For example, the NSF offers a label that indicates if a supplement meets its safety and performance standards, while United States Pharmacopeia verification means the supplement is free of contaminants. The Natural Products Association also verifies supplements that meet its quality guidelines and have been made with organic ingredients.