In the same year, the European Food Safety Authority also approved a dietary supplement health claim for calcium and vitamin D and the reduction of the risk of osteoporotic fractures by reducing bone loss. The U.S. FDA also approved Qualified Health Claims (QHCs) for various health conditions for calcium, selenium and chromium picolinate. QHCs are supported by scientific evidence, but do not meet the more rigorous “significant scientific agreement” standard required for an authorized health claim. If dietary supplement companies choose to make such a claim then the FDA stipulates the exact wording of the QHC to be used on labels and in marketing materials. The wording can be onerous: "One study suggests that selenium intake may reduce the risk of bladder cancer in women. However, one smaller study showed no reduction in risk. Based on these studies, FDA concludes that it is highly uncertain that selenium supplements reduce the risk of bladder cancer in women."
Vitamins can be natural or synthetic. Natural vitamins are extracted from food sources, while synthetic vitamins are formulated in laboratory processes. The only vitamin for which there is a noted difference between the natural and synthetic forms is vitamin E. The natural form is labeled d-alpha-tocopherol while the synthetic form is named dl-alpha-tocopherol, with the extra "l" signifying laboratory production. Natural vitamin E has been shown to be slightly more absorbable by the body than the synthetic version, although for other vitamins no significant differences in absorption have been noted.
For instance, foods rich in vitamin E and beta-carotene are healthy and can help reduce cancer risk. However, the U.S. Preventive Services Task Force (USPSTF) and the American Academy of Family Physicians (AAFP) recommend against taking vitamin E or beta-carotene for the prevention of cardiovascular disease. People who smoke or are at risk for lung cancer also should avoid beta-carotene. It can increase their risk of lung cancer.