Physiology · Temperature, exercise and metabolism
Vitamins and minerals: a physiological overview !
- Table to know
- Exam priority: medium
Vitamins and minerals are needed in small amounts, but without them blood, bones, nerves and the thyroid fail.
Updated 2026-11-01
Also called: Micronutrients
What it is
Vitamins are organic cofactors the body cannot make in sufficient amounts; minerals are inorganic elements. Fat-soluble vitamins (A, D, E, K) are absorbed with fat and stored, so they can build up and become toxic. Water-soluble ones (B complex, C) are stored little, except B12. This page sums up function and classic deficiency; the chemistry lives in Biochemistry.
Function and classic deficiency
| Nutrient | Key function | Deficiency |
|---|---|---|
| Vitamin A | Rhodopsin (vision), epithelia | Night blindness, xerophthalmia |
| Vitamin D | Intestinal calcium and phosphate absorption | Rickets (child), osteomalacia (adult) |
| Vitamin K | Carboxylation of factors II, VII, IX, X | Bleeding (newborn) |
| Thiamine (B1) | Decarboxylation of pyruvate and α-ketoglutarate | Beriberi, Wernicke encephalopathy |
| Niacin (B3) | NAD⁺/NADP⁺ | Pellagra: dermatitis, diarrhea, dementia |
| Vitamin C | Collagen hydroxylation; iron absorption | Scurvy: bleeding gums, petechiae |
| Cobalamin (B12) | DNA synthesis, myelin metabolism | Megaloblastic anemia, neuropathy |
| Iron | Hemoglobin, myoglobin, cytochromes | Microcytic anemia |
| Iodine | Thyroid hormones | Goitre, hypothyroidism |
Clinical notes
- Giving folate to someone with B12 deficiency corrects the anemia but not the nerve damage.
- Hypervitaminosis A (fish liver, supplements) causes raised intracranial pressure and liver injury.
- Newborns have little vitamin K (sparse gut flora): hence their bleeding risk.
Test yourself
Think of the answer, then tap the question to see it.
Why can a patient with chronic cholestasis bleed and fracture bones?
Without bile, fat and fat-soluble vitamins are not absorbed: vitamin K (clotting factors) and vitamin D (bone calcium) run short.
Why does B12 deficiency take years to appear after gastrectomy?
The liver stores several years of B12; deficiency appears only when that store runs out, once intrinsic factor is gone.
Why does vitamin C improve absorption of plant iron?
It reduces ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), the form the duodenal DMT1 transporter takes up.
Related topics
Related conditions
- Scurvy (vitamin C deficiency)
- Beriberi (thiamine deficiency)
- Rickets and osteomalacia
- Pellagra (niacin deficiency)
- Iron deficiency anaemia
- Goitre
- Pernicious anaemia
- Wernicke encephalopathy (thiamine deficiency)
In Biochemistry
- Vitamin A (retinol)
- Vitamin D (calcitriol)
- Thiamine (vitamin B1)
- Cobalamin (vitamin B12)
- Iron
- Iodine
- Vitamin C (ascorbic acid)
- Vitamin K (phylloquinone)
- Folate (vitamin B9)
Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.
Sources: 24.7 Nutrition and Diet (OpenStax (Rice University), 2022); Vitamins: MedlinePlus (MedlinePlus, US National Library of Medicine, 2026); Minerals: MedlinePlus (MedlinePlus, US National Library of Medicine, 2026); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 72). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).
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Representative model, for educational purposes only.