Essential vitamins, at a glance
There are 13 essential vitamins: A, C, D, E, K and eight B vitamins. We need them in small amounts for jobs ranging from vision and blood formation to the chemical reactions that keep cells working.
Two broad families
A, D, E and K are fat-soluble: dietary fat helps their absorption, and the body can store them. Vitamin C and the B vitamins are water-soluble. B12 is a useful exception to a common rule of thumb: despite being water-soluble, it can be stored for years.
The eight B vitamins are thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), biotin (B7), folate (B9), B6 and B12. Gaps in the numbering do not mean there are missing vitamins to find.
Different jobs, different evidence
Vitamin A helps with vision and cell development. Vitamin C is needed to make collagen, the structural protein in skin and connective tissue. Vitamin D helps regulate calcium and phosphate, while vitamin K helps activate proteins involved in blood clotting and bone metabolism.
Vitamin B12 supports red blood cell formation, DNA synthesis and the nervous system. These overlapping roles explain why the body needs a range of vitamins rather than one all-purpose nutrient.
The form matters
Some vitamin names cover several related compounds. Retinol is a form of vitamin A; beta-carotene is a precursor the body can convert into it. They contribute different amounts of vitamin A activity, so equal weights are not interchangeable.
Food tables and labels may show a specific form or a combined activity measure. Check the unit and serving alongside the number, especially when comparing different sources.
References
Source-checked educational draft. Human editorial review pending.
MedlinePlus, National Library of MedicineVitaminsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin A and Carotenoids: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin C: Fact Sheet for Health ProfessionalsSource accessed 2026-09-04NIH Office of Dietary SupplementsVitamin D: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin B12: Fact Sheet for Health ProfessionalsSource accessed 2026-09-04NIH Office of Dietary SupplementsVitamin K: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05