The supplement aisle is full of products promising more energy, better sleep and a stronger immune system. Most of them have little good research behind them. A short list stands out because the evidence is strong, but even these only help people with a specific need. Here are seven, who they are for, and what to look for when you buy.
This is general information, not medical advice. Check with a doctor or pharmacist before starting anything new, especially if you take medicines or are pregnant.
1. Folic acid, for anyone who could become pregnant
Taking folic acid before and during early pregnancy lowers the risk of serious birth defects of the brain and spine. Health agencies recommend 400 micrograms a day for anyone who could become pregnant, because these defects form before many people know they are pregnant. The NIH folate fact sheet has the details.
What to look for: a prenatal vitamin or a folic acid supplement with 400 to 800 micrograms. See our prenatal vitamins guide.
2. Vitamin D, for people who are low
Vitamin D helps your body absorb calcium and keep bones strong. People who get little sun, have darker skin, are older, or live far from the equator are more likely to run low. If your levels are normal, extra vitamin D has not been shown to prevent most diseases.
What to look for: vitamin D3 at 600 to 2,000 IU a day is common. A blood test tells you whether you need it. Read how much vitamin D you should take and compare products on our vitamin D page.
3. Vitamin B12, for adults over 50, vegans and some medicine users
Many people absorb less B12 from food as they age. Vegans get almost none from their diet. Long-term use of metformin or heartburn medicines can also lower levels. Low B12 can cause tiredness, numbness and memory problems. The NIH B12 fact sheet explains who is at risk.
What to look for: cyanocobalamin or methylcobalamin. Our guide to vitamin B12 for adults over 50 covers doses.
4. Iron, for people with a diagnosed deficiency
Iron deficiency is one of the most common nutrient problems worldwide, especially in people with heavy periods, pregnant people and frequent blood donors. Iron supplements work well for treating it. But too much iron is harmful, so do not take it without a blood test.
What to look for: follow your doctor's dose. Taking iron every other day may be better absorbed and easier on the stomach. Read iron supplements: who needs them.
5. Creatine, for people who lift or sprint
Creatine monohydrate reliably improves strength and power during short, intense exercise when combined with training. It is one of the most studied sports supplements, with a good safety record in healthy adults.
What to look for: plain creatine monohydrate powder, 3 to 5 grams a day. Follow our step-by-step guide on how to take creatine, and compare cost per 5 grams on our creatine page.
6. Protein powder, for people who struggle to eat enough protein
Protein powder is food, not magic, but it is a convenient way to reach your protein target if you are older, recovering from illness, training hard, or eat a mostly plant-based diet. It works as well as protein from food.
What to look for: a product with third-party testing and a short ingredient list. See our protein powder buying guide.
7. Omega-3s, for people who rarely eat fish
Fish oil reliably lowers high triglycerides, a type of blood fat, at prescription-level doses. For people who already eat fatty fish twice a week, extra omega-3s add little for most outcomes. The NIH omega-3 fact sheet summarizes the research.
What to look for: the amount of EPA and DHA per serving, not the total fish oil. Our guide on how to read omega-3 labels shows how.
What did not make the list
Popular supplements like multivitamins, collagen, turmeric and most "immune boosters" have weaker or mixed evidence for healthy people. That does not mean they never help, but it does mean you should be skeptical of big promises. Read are multivitamins worth it? and immune support supplements: what the evidence says.
How to buy any of these well
- Look for third-party testing seals such as USP or NSF. Learn what third-party tested means.
- Compare cost per serving, not price per bottle. Our guide on how to calculate cost per serving explains the math.
- Check for interactions with your medicines.