The right vitamin supplements can be useful for specific groups. Women trying to conceive or who are already pregnant need prenatal vitamins, especially folic acid, a B vitamin that has been shown to reduce the risk of life-threatening birth defects in a developing baby's brain and spinal cord.
People who are preparing for bariatric surgery, or who have already had it, are often counseled to take supplements because they tend not to eat enough food to meet the daily recommended amounts of certain nutrients. Further, it may be more difficult for them to maintain necessary levels of fat-soluble vitamins, those stored in fat cells, because of rapid weight loss.
Rumsey also recommends that older adults consider supplements, as our bodies are less efficient at extracting nutrients from food as we age. Specifically, older adults tend to be deficient in vitamin B12, which is necessary for healthy blood cells and nerves.
People of any age who don’t eat entire categories of food, such as strict vegans and vegetarians, may also want to consider B12 supplementation, Rumsey suggests, because the vitamin is only found naturally in animal foods such as meat, milk and milk products, and eggs.
Like B12, vitamin D only naturally occurs in animal products—liver, butter, fatty fish (such as salmon), and egg yolks. Your body, however, creates vitamin D when your skin is exposed to sunlight. It doesn’t take much if you’re fair skinned—just 10 to 15 minutes on a small area of exposed skin, three times a week—but if you’re dark skinned or live in places with less sun exposure, it will take longer in the sun, with more skin surface area exposed to get what you need (which comes with its own set of concerns). In those cases, vitamin D supplements could help.
If you use supplements, it pays to be choosy. Look for a third-party label review, such as those done by ConsumerLab.com, which indicates that the supplement was reviewed to ensure it contains the amount of nutrient the label claims it does. Those reviews do not, however, evaluate whether the supplement actually does what it claims to do.