Micronutrients at a Glance: A Reference Guide to Key Vitamins and Minerals

What Are Micronutrients and Why Do They Matter?

Micronutrients are vitamins and minerals your body needs in relatively small amounts — but their impact on health is anything but small. Unlike macronutrients (carbohydrates, protein, and fat), micronutrients don't provide calories. Instead, they enable nearly every biological process your body runs: converting food into energy, building and repairing tissue, regulating immune responses, and supporting brain function.

Most healthy adults can meet their micronutrient needs through a varied, whole-food diet. But certain life stages, dietary patterns, and health conditions can create gaps. Understanding what each key nutrient does — and where to find it — is a practical first step toward more informed eating. For deeper context on how nutrients appear on packaged foods, see how to read a Nutrition Facts label.

Key Vitamins: Roles, Sources, and Deficiency Signs

Vitamins are organic compounds divided into two categories based on how the body stores them.

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

Vitamin A supports vision, immune defense, and skin integrity. It's found in liver, dairy, eggs, and as beta-carotene in orange and dark leafy vegetables. Deficiency is rare in the U.S. but can impair night vision and immunity.

Vitamin D regulates calcium absorption and supports bone health and immune function. Skin synthesizes it from sunlight, but many Americans fall short — especially in northern latitudes during winter. Dietary sources include fatty fish, fortified dairy, and egg yolks. Low levels are associated with weakened bones and increased infection susceptibility.

Vitamin E acts as an antioxidant, protecting cells from oxidative damage. Nuts, seeds, and vegetable oils are top sources. Deficiency is uncommon but can appear with fat malabsorption disorders.

Vitamin K is essential for blood clotting and bone metabolism. Leafy greens like kale and spinach are the richest sources. People taking blood-thinning medications should discuss vitamin K intake with their healthcare provider.

Water-Soluble Vitamins (B Complex and C)

B vitamins — including B1 (thiamin), B2 (riboflavin), B3 (niacin), B6, B9 (folate), and B12 — collectively support energy metabolism and neurological function. Folate is critical during early pregnancy to prevent neural tube defects. B12 is found almost exclusively in animal products, making it a key concern for people following plant-based diets. See plant-based nutritional completeness for more on this.

Vitamin C supports collagen synthesis, wound healing, and immune function. It also enhances iron absorption from plant sources. Citrus fruits, bell peppers, and strawberries are excellent sources. Scurvy — a severe deficiency — is rare today but mild shortfalls can impair wound healing.

Essential Minerals: What They Do and Where to Find Them

Minerals are inorganic elements that the body cannot produce. They're grouped by how much the body requires: macrominerals (needed in larger amounts) and trace minerals (needed in smaller quantities).

Macrominerals

Calcium is foundational for bone and tooth strength, muscle contraction, and nerve signaling. Dairy products, fortified plant milks, tofu made with calcium sulfate, and leafy greens are reliable sources. Chronic low intake contributes to osteoporosis over time.

Magnesium participates in over 300 enzymatic reactions, including energy production, blood pressure regulation, and muscle function. Whole grains, legumes, nuts, and dark chocolate are good sources. Marginal magnesium intake is common in American diets.

Potassium helps maintain fluid balance, supports healthy blood pressure, and enables proper muscle and nerve function. Bananas, potatoes, beans, and leafy greens are excellent sources. Most Americans don't get enough.

Trace Minerals

Iron carries oxygen in the blood via hemoglobin. Red meat and shellfish provide highly absorbable heme iron; lentils, tofu, and fortified cereals provide non-heme iron. Iron-deficiency anemia is one of the most common nutritional deficiencies worldwide. Pair plant-based iron with vitamin C to improve absorption.

Zinc supports immune function, wound healing, and DNA synthesis. Meat, shellfish, legumes, and seeds are top sources. Vegetarians may need to consume more zinc-rich foods due to lower bioavailability from plant sources.

Iodine is required for thyroid hormone production, which regulates metabolism. Iodized salt, seafood, and dairy are primary sources in the U.S. Deficiency can cause thyroid enlargement and impair metabolism.

To see how these nutrients show up in food labels and ingredient lists, visit reading an ingredient list. For shopping strategies that put this knowledge into practice, see a practical grocery store walkthrough.

This article is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult a qualified healthcare provider before making changes to your diet or supplement routine, particularly if you have a medical condition or take medications.