What supplements should I take?
The right supplements come down to three things: what your diet already covers, how much sun and fish you get, and what symptoms you actually notice. Almost everyone benefits from vitamin D3 and omega-3; everything else depends on you.
Check my stack (2 min)The short answer for most adults
- Vitamin D3 — 1,000–2,000 IU/day if you rarely see the sun or eat fatty fish.
- Omega-3 (EPA/DHA) — 1–2 g/day if you eat fish less than twice a week.
- Magnesium — 200–400 mg glycinate at night if sleep, cramps, or stress are issues.
- B12 — 500–1,000 mcg/day if you're vegan, over 50, or on metformin/PPIs.
- Iron — only if a blood test or heavy periods point to it. Never stack blindly.
- Creatine — 3–5 g/day if you train. Strong evidence for strength and cognition.
Everything else — greens powders, collagen, immunity gummies, adaptogens — is optional and often duplicates what you already have.
The three factors that decide your stack
1. Diet — what's already covered
Eat fruit most days? Vitamin C is handled. Eat red meat weekly? Iron and B12 are handled. Eat fish twice a week? Omega-3 is handled. The point of supplements is to fill actual gaps, not to double up on what dinner already delivers. See the duplicates guides.
2. Lifestyle — sun, training, sleep
Indoor work + no fish = vitamin D and omega-3 are almost always low. Heavy training raises magnesium and protein needs. Poor sleep responds to magnesium glycinate and (sometimes) low-dose melatonin. Pregnancy needs folate and iodine on top of a prenatal.
3. Symptoms — what your body is telling you
Persistent fatigue often traces to B12, iron, or vitamin D. Brittle nails to biotin or protein. Restless legs to magnesium or iron. Symptoms alone aren't a diagnosis, but they narrow the shortlist. Browse the symptom guides.
Common mistakes to avoid
- Stacking a multivitamin + a greens powder + single-nutrient bottles — huge B/zinc overlap.
- Taking 1,000 mg vitamin C daily when you eat fruit — mostly excreted.
- Zinc from multi + immunity gummy → often over the 40 mg/day upper limit.
- Iron "just in case" — can be harmful in men and post-menopausal women.
- Calcium without vitamin K2 — see calcium + vitamin D.
Frequently asked questions
What supplements should I take every day?
For most adults with a mixed diet, only a few supplements have strong evidence for daily use: vitamin D3 (if you get little sun), omega-3 (if you rarely eat fatty fish), and a basic multivitamin as a safety net. Everything else — magnesium, B12, iron, zinc — should depend on your diet and symptoms, not a default routine.
How do I know which supplements I actually need?
Start with three inputs: what you eat in a normal week, how much sun and fish you get, and any symptoms (fatigue, poor sleep, brittle nails, low mood). Most gaps are predictable from those. VitaCheck asks the same questions a careful pharmacist would and returns a specific list.
Is it bad to take supplements you don't need?
Water-soluble vitamins (C, most Bs) are mostly excreted, but they still cost money. Fat-soluble vitamins (A, D, E, K) and minerals (iron, zinc, calcium, selenium) can build up and cross the tolerable upper limit — especially when a multivitamin, a single-nutrient bottle, and fortified foods stack on top of each other.
What supplements should a woman take?
Women of childbearing age typically need folate (400 mcg/day) and often iron if periods are heavy. After menopause, iron requirements drop and calcium + vitamin D + K2 become more important for bone. Pregnancy needs a dedicated prenatal, not a regular multivitamin.
What supplements should a man take?
Men without heavy training rarely need iron and often over-consume zinc from multis plus immunity gummies. Vitamin D3, omega-3, and magnesium (for sleep and training recovery) cover most cases. Creatine 3–5 g/day has the strongest evidence for strength and cognition if you train.
Do I need a multivitamin?
A basic multivitamin is a reasonable safety net if your diet is inconsistent. It's not a substitute for the two nutrients most people actually miss — vitamin D and omega-3 — because multivitamins usually under-dose both.
How many supplements is too many?
The number matters less than the overlap. Three well-chosen bottles beat eight that duplicate each other. The common failure is stacking a multivitamin + a greens powder + several single-nutrient bottles that all deliver the same B-complex and zinc.
Is this medical advice?
No. VitaCheck is educational. Reference values follow the NIH Office of Dietary Supplements for the adult general population. If you take prescription medication or have a chronic condition, run any new supplement past your doctor or pharmacist.