Risk factors beat symptom-guessing
Knowing whether you're in a higher-risk group is far more useful than matching symptoms to supplements. The NIH notes that while most people meet their needs through food, specific groups have well-documented gaps [1]. Here are the main ones and the nutrients they tend to involve.
Higher-risk groups
- Older adults absorb vitamin B12 less efficiently and often get less vitamin D and calcium — see [supplement guide for adults over 50](/learn/supplement-guide-adults-over-50).
- Pregnancy and breastfeeding raise needs for folate, iron, iodine, and choline — see [supplements during pregnancy](/learn/supplements-during-pregnancy).
- Vegans and vegetarians are at risk for vitamin B12 (found mainly in animal foods), and may need to attend to iron, zinc, and omega-3 — see [supplements for vegans](/learn/supplements-for-vegans).
- Malabsorption conditions (celiac, Crohn's, etc.) and weight-loss (bariatric) surgery reduce absorption of B12, iron, calcium, and fat-soluble vitamins.
- Heavy alcohol use lowers thiamin and folate — see [thiamin and who's at risk](/learn/thiamin-b1-deficiency-risk).
- Certain medications deplete nutrients (for example, long-term acid reducers and B12) — see [nutrient depletion from medications](/learn/nutrient-depletion-from-medications).
- Limited or restrictive diets, food insecurity, and very low calorie intake raise the risk across many nutrients.
What to do if you're in a risk group
- Target the likely gap rather than taking everything; the nutrient at risk depends on the cause.
- Ask about testing where a reliable marker exists (for example, ferritin, 25-hydroxyvitamin D, B12).
- Work with a clinician, especially after surgery or with a malabsorption condition, since needs and monitoring are individual.
For everyone else
If you eat a varied diet and aren't in a risk group, a broad multivitamin is optional insurance at most [2] — see do you need supplements. The point isn't to fear deficiency; it's to know whether your situation makes one plausible.