Vitamins: What to Take, When, and How to Stay Safe

Most people buy vitamins because they feel healthier taking them. But do you really need them? This page helps you figure out when supplements matter, how to pick good ones, and what to watch for so you don’t waste money or risk harm.

When a vitamin makes sense

Start with a quick check: are you eating a varied diet? If yes, you may not need routine multivitamins. Supplements are most useful when a deficiency is proven or very likely — for example, vitamin D for people with low blood levels, B12 for older adults or strict vegans, iron for people with confirmed iron-deficiency anemia, and folic acid during pregnancy. Ask your doctor for a simple blood test before you start a long-term supplement.

If you have a chronic condition, take certain prescription meds, or are pregnant, supplements may be recommended. Bring a list of everything you take to your pharmacist or clinician so they can advise on dose and timing.

How to pick a good supplement

Look beyond fancy labels. Choose products with third-party testing from groups like USP, NSF, or ConsumerLab. Check the ingredient list for active amounts (not just % of daily value), and avoid products that promise cure-all benefits. Prefer brands that list the form of the vitamin — for example, methylcobalamin for B12 or vitamin D3 (cholecalciferol) for better absorption.

Storage and expiry matter. Keep pills in a cool, dry place and toss anything past the expiration date. If a product smells off or looks discolored, don’t use it.

Common interactions and timing tips

Vitamins can change how drugs work. For example, vitamin K can reduce the effect of blood thinners like warfarin. Calcium and iron supplements can block absorption of levothyroxine and some antibiotics. Take levothyroxine on an empty stomach and separate calcium or iron by at least four hours. Iron absorbs better with vitamin C but avoid taking iron with dairy or calcium-containing foods.

Fat-soluble vitamins (A, D, E, K) need a meal with fat to absorb. Water-soluble vitamins (B and C) don’t, but taking them with food can reduce stomach upset. High doses of fat-soluble vitamins can build up in the body — don’t exceed recommended upper limits unless supervised by a clinician.

Want personalized advice? Ask your pharmacist for brand checks, dose recommendations, and timing tips. If labs show low levels, a short monitored course is often safer than indefinite high-dose self-treatment. Small changes — picking a tested brand, checking interactions, and getting one lab test — can protect your health and your wallet.