Know What Your Body Actually Needs
Cut through the supplement noise. Get clear, science-backed answers about the 13 vitamins your body can't live without.
Explore All 13 Vitamins
What each vitamin does, where to find it, and how much you actually need.
Explore →Personalized Supplement Guide
Answer a few questions. Get recommendations tailored to your age, diet, and lifestyle.
Take the Quiz →Deficiency Diseases
Scurvy. Rickets. Beriberi. Pellagra. The diseases that shaped medicine — and still matter today.
Learn More →Vitamins by the Numbers
Two Families, Very Different Rules
Water-Soluble (B-complex + C)
Your body uses what it needs and flushes the rest. Excess generally won't hurt you — but you need them daily.
6 Things Most People Get Wrong
You need exactly 13 — not 20, not 50.
Despite what the supplement aisle suggests, only 13 vitamins are truly essential. Everything else is marketing.
Vitamin D isn't really a vitamin.
It acts like a hormone. Your skin makes it from sunlight — which is why deficiency is so common in northern climates and indoor lifestyles.
Humans can't make vitamin C.
A gene mutation millions of years ago left us, other primates, and guinea pigs unable to synthesize it. That's why citrus saved sailors from scurvy.
Food beats pills — for most people.
A varied diet covers most healthy adults. Supplements matter for specific groups: pregnant women, older adults, vegans, people with absorption issues.
More isn't better.
Fat-soluble vitamins can become toxic at high doses. "Mega-dose" is rarely a good word.
The vitamin era is younger than you think.
The word "vitamin" was coined in 1912. The last vitamin (B12) was isolated in 1948 — within living memory.
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