Vitamins and Minerals: What Micronutrients Actually Do Inside Your Body

What Are Micronutrients — And Why Do They Matter?

Your body runs on two broad categories of nutrients: macronutrients (carbohydrates, protein, and fat), which supply energy and building blocks, and micronutrients — vitamins and minerals — which regulate virtually every biological process that keeps you alive and well. To understand how the two categories relate, see our overview of macronutrients and micronutrients together.

The prefix micro refers to quantity, not importance. Your body needs vitamins and minerals in milligram or even microgram amounts — far smaller than the grams of carbs or protein you consume daily. Yet without them, core functions break down: enzymes stall, cells can't divide properly, bones lose density, and the immune system falters.

Unlike macronutrients, the human body cannot synthesize most micronutrients on its own (with a few exceptions, such as vitamin D produced through sun exposure). That means you must obtain them consistently through food — or, in specific circumstances, through supplementation guided by a healthcare provider.

Vitamins: Fat-Soluble vs. Water-Soluble

The 13 essential vitamins are divided into two groups based on how they dissolve and how the body handles them.

Fat-Soluble Vitamins (A, D, E, K)

These vitamins dissolve in fat and are stored in body tissues and the liver. Because they accumulate, you don't need to consume them every single day — but excess intake, especially from high-dose supplements, can build to harmful levels over time.

• Vitamin A — supports vision in low light, immune defense, and skin cell turnover. Found in liver, dairy, eggs, and as beta-carotene in orange and dark leafy vegetables.
• Vitamin D — critical for calcium absorption and bone mineralization; also plays a role in immune signaling. Synthesized by skin in sunlight; found in fatty fish and fortified foods.
• Vitamin E — an antioxidant that helps protect cell membranes from oxidative damage. Found in nuts, seeds, and vegetable oils.
• Vitamin K — essential for blood clotting and bone metabolism. Found in leafy greens such as kale and spinach.

Water-Soluble Vitamins (B Vitamins and Vitamin C)

These dissolve in water and are not stored significantly by the body — excess amounts are largely excreted in urine. This means they need to be replenished more regularly through diet, and toxicity from food sources is uncommon.

• B vitamins (including B1/thiamine, B2/riboflavin, B3/niacin, B6, B12, folate, and others) — act as coenzymes in energy metabolism, red blood cell production, and neurological function. Found across whole grains, meat, fish, dairy, legumes, and leafy greens.
• Vitamin C — supports collagen synthesis, wound healing, and immune function; also enhances iron absorption from plant foods. Found in citrus fruits, bell peppers, broccoli, and strawberries.

Minerals: Major and Trace Elements

Minerals are inorganic elements absorbed from food and water. They are grouped by how much the body needs: major minerals are required in larger amounts (hundreds of milligrams daily), while trace minerals are needed in very small amounts.

Major Minerals

• Calcium — the most abundant mineral in the body; provides structural strength to bones and teeth, and supports muscle contraction and nerve signaling. Found in dairy products, fortified plant milks, tofu, and leafy greens.
• Magnesium — involved in over 300 enzymatic reactions, including energy production and protein synthesis. Found in nuts, seeds, whole grains, and dark chocolate.
• Potassium — helps regulate fluid balance, muscle contractions, and blood pressure. Found in bananas, potatoes, beans, and yogurt.
• Sodium — critical for nerve transmission and fluid balance, though most Americans consume more than needed. Present in most foods; especially high in processed and packaged items.

Key Trace Minerals

• Iron — essential for making hemoglobin, the protein in red blood cells that carries oxygen. Found in red meat, poultry, seafood, and legumes. Vitamin C consumed alongside plant-based iron improves absorption.
• Zinc — supports immune function, wound healing, and DNA synthesis. Found in meat, shellfish, legumes, and seeds.
• Iodine — required for thyroid hormone production, which regulates metabolism. Found in iodized salt, seafood, and dairy.
• Selenium — acts as an antioxidant and supports thyroid function. Brazil nuts are an especially concentrated source; also found in fish and grains.

How to Get Enough Through Food

The most reliable path to adequate micronutrient intake is a varied diet built around whole, minimally processed foods. Major dietary guidelines — including those from the USDA — consistently emphasize variety because no single food provides every essential nutrient. Think of different food groups as complementary pieces: each food group contributes distinct nutrients that the others don't fully cover.

A few practical principles support good micronutrient status:

1. Eat a wide range of colors. Plant pigments often correspond to specific phytochemicals and micronutrients — orange foods tend to be high in beta-carotene; dark leafy greens supply vitamin K, folate, and magnesium.
2. Pair nutrients strategically. Vitamin C enhances non-heme iron absorption from plant foods. Fat consumed alongside fat-soluble vitamins improves their uptake.
3. Minimize heavy processing. Refining grains removes much of their B vitamin and mineral content, which is why choosing whole grains over refined versions matters.
4. Consider your life stage. Needs shift during pregnancy, infancy, adolescence, and older adulthood. If you fall into a higher-need group, or follow a plant-focused diet, a healthcare provider or registered dietitian can help identify any gaps. For plant-based eaters specifically, see our guide on getting enough vitamins and minerals on a plant-based diet.

Supplements can help address confirmed deficiencies, but they are not a straightforward substitute for dietary variety. If you're unsure whether your intake is adequate, a registered dietitian or your primary care provider is the right resource — not the supplement aisle.

To learn how to evaluate micronutrient content when shopping, our guide to reading nutrition labels walks through Percent Daily Values and what they mean in practice. And if you've heard conflicting claims about vitamins and minerals, our article on common micronutrient myths separates fact from fiction.

This article is for general informational and educational purposes only and does not constitute medical or dietary advice. Consult a qualified healthcare professional for guidance specific to your health needs.