The vitamin aisle is the most crowded and most overhyped part of the supplement world. The points below help you avoid buying what you don't need.
First question: are you actually low?
The logic of a supplement is to fill a gap. Taking a vitamin you aren't short on doesn't boost its effect: your body uses what it needs and either excretes or stores the rest.
So the best starting point isn't a guess but a measurement: a blood test. For nutrients where shortfalls are common, such as vitamin D and B12, choosing a dose without testing is guesswork. Taking high doses on the assumption that "everyone is deficient" can lead to unnecessary buildup of some vitamins, especially fat-soluble ones.
Multivitamin or single nutrient?
Multivitamins provide many nutrients at modest doses. If you have a specific shortfall, that's often not enough: for a significant vitamin D deficiency, the amount in a multivitamin is frequently low.
The reverse is also true: without a known shortfall, high-dose single-nutrient products are unnecessary. A multivitamin can be a general safety net for someone with an irregular diet; it isn't a targeted treatment.
What %DV on the label means
The Supplement Facts panel shows %DV (percent Daily Value): how much of a daily reference amount one serving provides. 100% meets the reference. Some products list values far above that, such as 1,000%.
A higher percentage isn't automatically better. With water-soluble vitamins (C and the B group), the excess is excreted, so part of what you paid for is wasted. With fat-soluble vitamins (A, D, E, K), the excess can accumulate, so a high dose isn't desirable in itself.
Forms matter
The same mineral comes in different compounds with different absorption and tolerance. Magnesium is the best-known example: citrate, glycinate and oxide forms differ, including in how they sit with your stomach. Vitamin D comes as D2 or D3.
The label should state which form is used; if it doesn't, that's missing information in itself. Form also shows up in price: cheaper products tend to use the cheapest form.
Compare the cost of a daily dose
Bottles say "60 capsules" or "120 tablets," but daily doses differ: one capsule a day for some products, three for others. The right comparison is what one day's dose costs.
A 60-capsule bottle at two a day lasts 30 days; a 90-capsule bottle at one a day lasts 90. Bottle price hides that difference.
Are "sports" multivitamins really different?
Products labeled for athletes usually have higher doses and sometimes extra ingredients. It's true that regular training raises some needs, but not necessarily enough to make a standard multivitamin inadequate. If the price gap is large, check whether the ingredient difference actually justifies it.
Combinations to space out
Some minerals compete for absorption; calcium and iron are the best-known example. Multivitamins already combine them. If you take separate high-dose supplements, spacing them apart is common advice. If you take regular medication, ask your doctor or pharmacist about interactions.
Quality marks
In the US, supplements aren't approved by the FDA before they're sold. Independent verification such as the USP Verified mark or NSF certification checks that a product contains what the label says. It's not required, but it's a useful sign.
Shelf life and storage
Vitamins can lose potency over time. A big, cheap bottle stops being a bargain if you can't finish it at your daily dose before it expires. Store away from light, somewhere cool and dry.
This isn't medical advice
Vitamin and mineral supplements, especially at high doses, are a medical topic. If you take medication, are pregnant, or have a health condition, decide on doses with a doctor or registered dietitian.
Compare current prices and real price history on our vitamin and mineral prices page.