The 10 Supplements People Are Actually Deficient In

95% of U.S. adults fall short on fibre. 90% on choline. 90% on long-chain omega-3. The U.S. is essentially short on potassium as a country. Multivitamins still lead with C and E — neither of which is the actual gap. The 10 nutrients where pills genuinely fill a hole.

1. Potassium — Median intake ~2,400–2,800 mg/day (men) and 1,800–2,300 (women). AI is 3,400 / 2,600. Essentially the entire U.S. population is short.
2. Fibre — ~95% of U.S. adults below the 25–38 g/day target.
3. Choline — ~90% below the AI. Critical for liver, brain, and pregnancy.
4. Omega-3 (EPA + DHA) — ~90% of U.S. adults below the AHA's 250 mg/day from seafood.
5. Vitamin K2 — No formal RDA, but ~75% of adults below intakes associated with cardiovascular and bone benefits.
6. Magnesium — ~50% of U.S. adults below the EAR (320 mg women / 420 mg men).
7. Vitamin D — ~42% of U.S. adults have serum 25(OH)D below 30 ng/mL.
8. Calcium — ~40% below the EAR (800–1,000 mg). Highest gaps in adolescent girls and adults over 50.
9. Iron (women 19–50) — ~25% have low iron stores; ~10% meet criteria for iron-deficiency anemia.
10. Vitamin B12 (adults 50+) — ~20% of older adults are low or borderline, primarily from age-related stomach-acid decline.

Bottom line

Most "deficiency" marketing is aimed at the wrong nutrients. Multivitamins lead with vitamin C and E. The actual population-wide gaps are potassium, fibre, choline, omega-3, K2, magnesium, and D. Fix those and you've covered most of what supplementation can plausibly do for an average adult.

See the full deficiency rankings with NHANES-grade citations on Discover →