[troutman]

Research says they are largely useless unless you have a specific deficiency.

https://sciencebasedmedicine.org/?s=...&submit=Search

Based upon the totality of evidence the best current recommendation is to have a well-rounded diet with sufficient fruits and vegetables, which should be able to provide most people with all the micronutrients they require. There is no evidence to support routine supplementation. There is also reason to avoid taking megadoses of vitamins, as this can cause toxicity, and even short of toxicity the evidence becomes more compelling at higher doses of the risks of supplementation

Beware of friends selling vitamins through MLM operations like Usana.

http://www.skeptical-science.com/science/vitamin-myth/

https://www.scientificamerican.com/a...y-doctors-say/

"The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified and they should be avoided," the physicians wrote in an editorial published along with the studies.
This message is especially aimed at people who have no signs of nutritional deficiency — meaning most supplement users in the United States, the researchers said.

"Study after study comes back negative — yet people continue to take supplements, now at record rates," said Dr. Edgar Miller, one of the five authors of the editorial and a professor of medicine and epidemiology at Johns Hopkins University in Baltimore.

There may be a psychological component to taking supplements, Miller said. Despite evidence showing supplements hold no benefit for the general population, some people may rationalize they need supplements because their diets lack necessary nutrients, Miller told LiveScience.

The new findings are in line with those of previously published studies that have found no benefits from dietary supplements, including B vitamins and antioxidants, and even suggested possible harms. Results of clinical trials involving tens of thousands of people have shown that beta-carotene, vitamin E and possibly high doses of vitamin A supplements actually increase death rates, the researchers said.

"We believe that the case is closed — supplementing the diet of well-nourished adults with most mineral or vitamin supplements has no clear benefit and might even be harmful," the researchers wrote in their editorial.