Micronutrients: The Vitamins and Minerals Your Body Can't Make Itself

What Are Micronutrients?

Your body runs on two broad categories of nutrients: macronutrients (carbohydrates, proteins, and fats) and micronutrients. While macros supply energy and raw building material, micronutrients — vitamins and minerals — do the regulatory and structural work that keeps every system functioning. If you want a grounding in how macros fit into the bigger picture, see our overview of macronutrients.

Unlike macronutrients, micronutrients are needed only in small amounts — milligrams or micrograms — yet their absence has outsized consequences. The defining feature is that the human body cannot synthesize most of them in adequate quantities, so they must come from food or, in some cases, supplementation under professional guidance.

Vitamins are organic compounds, meaning they contain carbon and can be broken down by heat, air, or acid. Minerals are inorganic elements — iron, calcium, zinc — that retain their structure regardless of cooking or processing. Both categories are subdivided further, and those distinctions affect how your body absorbs and stores them.

Fat-Soluble vs. Water-Soluble Vitamins

Vitamins fall into two groups based on how the body handles them, and the difference is clinically meaningful.

Fat-soluble vitamins (A, D, E, K) dissolve in fat and are stored in the liver and adipose (fat) tissue. Because they accumulate, both deficiency and excess can cause health problems over time. Vitamin D is unique in this group: your skin can produce it when exposed to UV-B sunlight, but most people in northern latitudes or with limited sun exposure don't produce enough year-round.

Water-soluble vitamins (the eight B vitamins and vitamin C) dissolve in water and are generally not stored in large amounts — excess is excreted in urine. This means deficiencies can develop relatively quickly if intake drops, but toxicity from food sources is rare. B vitamins are central to energy metabolism; vitamin C is critical for immune function and collagen synthesis.

For a broader view of how these nutrients slot into overall dietary patterns, our foundational nutrition guide covers the full picture.

Key Minerals and Why They Matter

Minerals are categorized as macrominerals (needed in larger amounts: calcium, phosphorus, magnesium, sodium, potassium, chloride, sulfur) and trace minerals (needed in smaller amounts: iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium, molybdenum).

A few minerals deserve particular attention because deficiencies are common in the U.S. population:

• Iron — essential for oxygen transport via hemoglobin; deficiency is the most widespread nutritional deficiency globally. Women of reproductive age and people who don't eat red meat are at higher risk.
• Calcium — critical for bone density, muscle contraction, and nerve signaling. Adequate intake in youth and middle age reduces the risk of osteoporosis later in life.
• Magnesium — involved in over 300 enzymatic reactions, including those regulating blood glucose and blood pressure. Dietary surveys consistently show many adults fall short.
• Iodine — required for thyroid hormone production. Iodized salt is the primary source for much of the U.S. population.

Dietary fiber works alongside micronutrients to support gut health and nutrient absorption — our article on dietary fibre explains why most people don't get enough.

Recognizing and Addressing Deficiencies

Micronutrient deficiencies are often subtle before they become severe. Fatigue, poor wound healing, brittle nails, frequent illness, or changes in skin and hair can all signal shortfalls — but these symptoms overlap with many other conditions. A healthcare provider can order blood tests to confirm specific deficiencies before recommending supplements.

The most reliable strategy for meeting micronutrient needs is a varied whole-food diet: dark leafy greens, legumes, whole grains, nuts, seeds, fish, dairy or fortified alternatives, and a range of colorful fruits and vegetables. No single food or supplement covers every gap. Highly restrictive diets — whether by choice or circumstance — carry the highest deficiency risk and warrant closer monitoring by a nutrition professional.

This article provides general nutrition information for educational purposes and is not a substitute for personalized medical or dietary advice. Consult a qualified healthcare professional before making significant dietary changes or beginning any supplement regimen.