| Total essential vitamins | 13 (4 fat-soluble, 9 water-soluble) (National Institutes of Health, Office of Dietary Supplements) |
| Essential dietary minerals | At least 16 recognized as essential (Institute of Medicine / National Academies) |
| Most common global micronutrient deficiency | Iron deficiency (World Health Organization) |
| Vitamin D synthesis | Produced in skin via UVB sunlight exposure (NIH Office of Dietary Supplements) |
| B12 in plant foods | Virtually absent without fortification (NIH Office of Dietary Supplements) |
| Vitamin C and iron absorption | Vitamin C can significantly enhance non-heme iron absorption (American Journal of Clinical Nutrition) |
What Are Micronutrients and Why Do They Matter?
Macronutrients — carbohydrates, protein, and fat — supply the body with energy. Micronutrients do something different: they make energy use possible. Vitamins and minerals act as cofactors, structural components, and signaling molecules across virtually every system in the body, from immune defense and bone formation to DNA repair and hormone synthesis.
The word micro refers to the amounts required, not to their importance. The body needs most vitamins and minerals in milligram or microgram quantities, yet a sustained shortfall of even a single one can have measurable consequences. See our practical checklist on nutritional gaps for signs worth watching. For a broader nutrition foundation, the macronutrient overview is a useful starting point.
Micronutrient
A vitamin or mineral required by the body in small amounts to support growth, metabolism, and normal physiological function. Unlike macronutrients, micronutrients do not provide calories.
Fat-soluble vitamin
Vitamins A, D, E, and K, which are absorbed with dietary fat and stored in body tissue. Because they accumulate, excessive intake from supplements carries a risk of toxicity.
Water-soluble vitamin
The B vitamins and vitamin C, which dissolve in water and are not significantly stored by the body. Regular dietary intake is needed to maintain adequate levels.
Trace mineral
A mineral the body requires in very small amounts — typically micrograms to low milligrams per day. Examples include iron, zinc, iodine, and selenium. Small quantities do not imply low importance.
Bioavailability
The proportion of a nutrient that is actually absorbed and used by the body. Bioavailability varies by food source, preparation method, and the presence of other nutrients consumed at the same time.
Cofactor
A non-protein molecule — often a vitamin or mineral — that an enzyme requires to function. Many B vitamins, for example, serve as cofactors in energy-producing reactions.
Vitamins: Fat-Soluble vs. Water-Soluble
The thirteen recognized essential vitamins fall into two broad categories based on how the body stores and handles them.
Fat-Soluble Vitamins (A, D, E, K)
These vitamins are absorbed alongside dietary fat and stored in body fat and the liver. Because they accumulate, prolonged excess from high-dose supplements can reach toxic levels — a consideration worth discussing with a healthcare provider before supplementing.
- Vitamin A — Supports vision (especially low-light), immune function, and cell differentiation. Found in liver, dairy, eggs, and as provitamin A carotenoids in orange and dark-green vegetables.
- Vitamin D — Regulates calcium absorption and is critical for bone health and immune modulation. Synthesized in skin on sun exposure; dietary sources include fatty fish and fortified foods. Its relationship with calcium is explored in the Vitamin D and Calcium guide.
- Vitamin E — A fat-soluble antioxidant that protects cell membranes. Found in nuts, seeds, and vegetable oils.
- Vitamin K — Essential for blood clotting and bone metabolism. Leafy greens are the primary dietary source.
Water-Soluble Vitamins (B Vitamins and Vitamin C)
Water-soluble vitamins are not stored in appreciable amounts; excess is excreted in urine. This means regular dietary intake matters more, and deficiencies can develop relatively quickly.
- B vitamins (B1, B2, B3, B5, B6, B7, B9, B12) — Collectively drive energy metabolism, red blood cell production, and neurological function. Whole grains, legumes, meat, dairy, and leafy greens cover most of the group; B12 is found almost exclusively in animal products, making it a key consideration on plant-based diets. See nutrients to watch on a vegan diet.
- Vitamin C — Supports collagen synthesis, iron absorption from plant foods, and antioxidant defense. Citrus fruits, bell peppers, and broccoli are excellent sources.
| Total essential vitamins | 13 (4 fat-soluble, 9 water-soluble) (National Institutes of Health, Office of Dietary Supplements) |
| Essential dietary minerals | At least 16 recognized as essential (Institute of Medicine / National Academies) |
| Most common global micronutrient deficiency | Iron deficiency (World Health Organization) |
| Vitamin D synthesis | Produced in skin via UVB sunlight exposure (NIH Office of Dietary Supplements) |
| B12 in plant foods | Virtually absent without fortification (NIH Office of Dietary Supplements) |
| Vitamin C and iron absorption | Vitamin C can significantly enhance non-heme iron absorption (American Journal of Clinical Nutrition) |
Essential Minerals: Macro and Trace
Minerals are inorganic elements the body cannot synthesize. They are grouped by the quantity needed: macrominerals (needed in hundreds of milligrams daily) and trace minerals (needed in much smaller amounts, though no less essential).
Key Macrominerals
- Calcium — The most abundant mineral in the body; provides structural integrity to bones and teeth and is required for muscle contraction and nerve signaling.
- Magnesium — A cofactor in more than 300 enzymatic reactions, including energy production, protein synthesis, and blood glucose regulation. Whole grains, nuts, seeds, and dark leafy greens are reliable sources. The in-depth magnesium guide covers its many functions.
- Potassium — Maintains fluid balance and normal heart rhythm. Bananas, potatoes, beans, and dairy are good sources.
- Phosphorus — Partners with calcium in bone structure and is integral to the energy molecule ATP. Found in protein-rich foods including meat, fish, dairy, and legumes.
Important Trace Minerals
- Iron — Required for hemoglobin and oxygen transport. Heme iron from animal foods is more bioavailable; pairing non-heme iron from plants with vitamin C enhances absorption.
- Zinc — Supports immune function, wound healing, and enzyme activity. Found in meat, shellfish, legumes, and pumpkin seeds.
- Iodine — Necessary for thyroid hormone synthesis, which regulates metabolism. Iodized salt and seafood are primary sources.
- Selenium — An antioxidant cofactor and immune modulator. Brazil nuts are exceptionally high; fish and whole grains also contribute.
Food First, Supplements Second
For most healthy adults eating a varied diet, whole foods provide micronutrients in combinations and ratios the body is well adapted to use. Supplements can address specific documented deficiencies or needs identified by a healthcare provider, but they are not a reliable substitute for dietary variety. High-dose supplementation of fat-soluble vitamins in particular carries risks and should always involve professional guidance.
Micronutrient needs interact in important ways. Before adding supplements, it is worth reading about nutrient interactions that affect absorption, and consulting a qualified healthcare provider or registered dietitian for personalized guidance. For a broader view of dietary nutrients, explore the Nutrients & Supplements hub.
This article provides general nutrition information and education only. It is not a substitute for personalized medical or dietary advice. Always consult a qualified healthcare professional regarding your individual health needs.