What Are Micronutrients — and Why Do They Matter?

Micronutrients are vitamins and minerals the body needs in relatively small amounts, yet they drive nearly every essential biological process — from converting food into energy to repairing DNA and keeping the immune system functional. Unlike macronutrients such as carbohydrates, proteins, and fats, micronutrients provide no calories, but their absence can still have serious health consequences.

Vitamins are organic compounds, meaning they contain carbon and can be broken down by heat, air, or cooking. Minerals are inorganic elements sourced from soil and water that retain their chemical structure regardless of preparation. Together, they form a dense network of co-factors that support hormone production, bone formation, nerve signaling, and antioxidant defense.

Most people in the United States can meet their micronutrient needs through a varied, balanced diet. However, certain groups — including pregnant individuals, older adults, and those with specific medical conditions — may face higher risk of deficiency. For personalized guidance, always consult a qualified healthcare provider. See also how micronutrient needs shift across life stages.

Total essential vitamins 13 (National Institutes of Health, Office of Dietary Supplements)
Essential dietary minerals 16 recognized (Institute of Medicine, Dietary Reference Intakes)
Most common U.S. micronutrient shortfalls Vitamin D, calcium, potassium, iron (2020–2025 Dietary Guidelines for Americans)
Fat-soluble vitamins A, D, E, K
Water-soluble vitamins C and 8 B vitamins
Best overall dietary strategy Varied whole-food diet (2020–2025 Dietary Guidelines for Americans)

Key Vitamins: Functions and Food Sources

Vitamins are divided into two categories based on how the body stores and processes them:

  • Fat-soluble vitamins (A, D, E, K) — stored in fatty tissue and the liver; can accumulate to excess if over-supplemented.
  • Water-soluble vitamins (C and the eight B vitamins) — not stored in significant amounts; excess is excreted in urine, so regular dietary intake is necessary.

Vitamin A

Essential for vision (especially in low light), immune function, and cell growth. Found in liver, dairy, eggs, and as beta-carotene in orange and dark-green vegetables like sweet potatoes and spinach.

B Vitamins

This family includes thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), B6, biotin (B7), folate (B9), and B12. Collectively they support energy metabolism, red blood cell production, and neurological function. Folate is especially critical during early pregnancy for neural tube development. B12 is found almost exclusively in animal products, making supplementation worth discussing with a doctor for those following plant-based diets.

Vitamin C

A powerful antioxidant that supports collagen synthesis, wound healing, and immune response. Citrus fruits, bell peppers, strawberries, and broccoli are excellent sources.

Vitamin D

Supports calcium absorption, bone health, and immune regulation. The skin synthesizes it from sunlight exposure, but many Americans — particularly those in northern latitudes or with limited sun access — have insufficient levels. Dietary sources include fatty fish, fortified dairy, and egg yolks.

Vitamin E

Acts as an antioxidant protecting cell membranes. Found in nuts, seeds, and vegetable oils.

Vitamin K

Critical for blood clotting and bone metabolism. Leafy greens like kale, collards, and spinach are the richest sources.

Fat-soluble vitamins

Vitamins A, D, E, and K, which dissolve in fat and are stored in the body's fatty tissues and liver. Because they accumulate, excessive intake from supplements can reach harmful levels.

Water-soluble vitamins

Vitamin C and the eight B vitamins, which dissolve in water and are not stored in large amounts. They must be consumed regularly through food, as excess is excreted in urine.

Macrominerals

Minerals the body requires in relatively larger amounts, including calcium, magnesium, phosphorus, potassium, sodium, and chloride. They support structural and metabolic functions.

Trace minerals

Minerals needed only in very small quantities, such as iron, zinc, iodine, selenium, and copper. Despite the tiny amounts required, deficiencies can have significant health effects.

Bioavailability

The proportion of a nutrient the body can actually absorb and use from a given food or supplement. Factors like food preparation, the presence of other nutrients, and individual health status all affect bioavailability.

Heme iron

A form of iron found in animal-derived foods such as red meat, poultry, and fish. It is absorbed more efficiently by the body compared to non-heme iron from plant sources.

Essential Minerals: From Calcium to Zinc

Minerals are classified as either macrominerals (needed in larger amounts) or trace minerals (needed in smaller quantities but no less essential).

Calcium

The most abundant mineral in the body, calcium is foundational to bone and tooth structure, muscle contraction, and nerve transmission. Dairy products, fortified plant milks, tofu, and dark leafy greens are primary sources.

Iron

Iron is a component of hemoglobin, the protein in red blood cells that carries oxygen throughout the body. Animal-based (heme) iron from red meat, poultry, and fish is absorbed more readily than plant-based (non-heme) iron from legumes and fortified cereals. Pairing non-heme sources with vitamin C improves absorption.

Magnesium

Involved in over 300 enzymatic reactions, including muscle and nerve function, blood glucose regulation, and protein synthesis. Found in nuts, seeds, whole grains, and leafy greens.

Potassium

Supports healthy blood pressure, fluid balance, and muscle contractions. Bananas, potatoes, beans, and yogurt are good sources.

Zinc

Supports immune function, wound healing, and DNA synthesis. Found in shellfish, meat, legumes, and seeds.

Iodine

Essential for thyroid hormone production, which regulates metabolism and growth. Iodized salt and seafood are the primary dietary sources in the U.S.

For a broader look at nutrition vocabulary, explore our guide to common nutritional terms.

This article is for general informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before making changes to your diet or supplement routine.