Micronutrients at a Glance: Essential Vitamins and Minerals Reference
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In this article
A quick-reference overview of key vitamins and minerals, their functions, common food sources, and signs of deficiency.
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 enormous. Unlike macronutrients like carbohydrates, proteins, and fats, micronutrients don't supply calories. Instead, they drive hundreds of biochemical processes: from energy metabolism and immune defense to bone formation and nerve signaling.
If you're new to thinking about nutrition, understanding micronutrients is a practical next step. Deficiencies — even mild ones — can affect energy, cognition, immune function, and long-term health. This reference is designed to give you a clear, scannable overview of the vitamins and minerals most relevant to everyday American adults.
Micronutrients
Vitamins and minerals required by the body in small amounts to support essential physiological processes. Unlike macronutrients, they provide no caloric energy but are indispensable for health.
Fat-Soluble Vitamins
Vitamins A, D, E, and K, which dissolve in fat and are stored in the body's fatty tissue and liver. Because they accumulate, excessive supplementation can lead to toxicity.
Water-Soluble Vitamins
Vitamin C and the B vitamins, which dissolve in water and are not stored in large amounts. Regular dietary intake is necessary to maintain adequate levels.
Bioavailability
The proportion of a nutrient that is actually absorbed and used by the body after ingestion. Bioavailability varies by food source, preparation method, and individual factors.
Trace Minerals
Minerals the body needs in very small amounts — including iron, zinc, and iodine — that are nonetheless essential for normal physiological function.
Deficiency
A state in which the body lacks an adequate supply of a specific nutrient, potentially leading to measurable physical symptoms or increased disease risk.
Key Vitamins: Functions, Sources, and Deficiency Signs
Vitamins fall into two categories: fat-soluble (A, D, E, K — stored in body fat and liver) and water-soluble (C and the B vitamins — not stored long-term, requiring regular dietary intake).
| Number of essential vitamins | 13 (National Institutes of Health (NIH), Office of Dietary Supplements) |
| Number of essential dietary minerals | At least 16 (World Health Organization guidance) |
| Most common nutrient deficiency globally | Iron (World Health Organization) |
| Vitamin D deficiency prevalence (U.S. adults) | Approximately 35% (National Health and Nutrition Examination Survey (NHANES) data) |
| Fat-soluble vitamins | A, D, E, K |
| Best overall micronutrient strategy | Dietary variety from whole foods (Dietary Guidelines for Americans) |
| Vitamin | Primary Role | Common Food Sources | Deficiency Signs |
|---|---|---|---|
| Vitamin A | Vision, immune function, skin integrity | Liver, dairy, eggs, orange/yellow vegetables | Night blindness, dry skin, impaired immunity |
| Vitamin D | Calcium absorption, bone health, immune regulation | Fatty fish, fortified dairy, sunlight exposure | Bone pain, muscle weakness, fatigue |
| Vitamin C | Collagen synthesis, antioxidant activity, iron absorption | Citrus fruits, bell peppers, broccoli, strawberries | Slow wound healing, bleeding gums, fatigue |
| Vitamin B12 | Nerve function, red blood cell production, DNA synthesis | Meat, fish, dairy, fortified plant foods | Fatigue, nerve tingling, cognitive changes |
| Folate (B9) | DNA replication, cell division, fetal neural development | Leafy greens, legumes, fortified grains | Anemia, fatigue; neural tube defects in pregnancy |
| Vitamin K | Blood clotting, bone metabolism | Leafy greens, fermented foods, some vegetable oils | Impaired clotting, potential bone fragility |
Essential Minerals: What They Do and Where to Find Them
Minerals are inorganic elements absorbed from food and water. Macrominerals (like calcium and magnesium) are needed in larger amounts; trace minerals (like iron and zinc) are required in smaller quantities but are no less critical.
| Mineral | Primary Role | Common Food Sources | Deficiency Signs |
|---|---|---|---|
| Calcium | Bone and tooth structure, muscle contraction, nerve signaling | Dairy, fortified plant milks, tofu, leafy greens | Muscle cramps, low bone density |
| Iron | Oxygen transport in red blood cells | Red meat, legumes, fortified cereals, spinach | Fatigue, pallor, shortness of breath |
| Magnesium | Energy production, muscle and nerve function, blood sugar regulation | Nuts, seeds, whole grains, dark leafy greens | Muscle cramps, irritability, irregular heartbeat |
| Zinc | Immune response, wound healing, taste and smell | Meat, shellfish, legumes, nuts, seeds | Impaired immunity, slow wound healing, hair loss |
| Potassium | Blood pressure regulation, fluid balance, heart function | Bananas, potatoes, beans, avocado | Muscle weakness, fatigue, irregular heartbeat |
| Iodine | Thyroid hormone production, metabolism | Iodized salt, seafood, dairy | Goiter, fatigue, impaired metabolism |
People following plant-based diets should pay particular attention to iron, zinc, calcium, iodine, and B12, as these are less bioavailable or entirely absent in many plant foods.
Putting It Into Practice
For most healthy adults, a varied whole-food diet — emphasizing vegetables, fruits, legumes, whole grains, lean proteins, and dairy or fortified alternatives — provides adequate micronutrients without supplementation. Dietary variety remains the most evidence-supported strategy for meeting micronutrient needs. Adequate hydration also plays a supporting role; see how water fits into your nutrition for more context.
Certain populations have elevated needs or absorption challenges: older adults (vitamin D, B12), pregnant individuals (folate, iron), people with limited sun exposure (vitamin D), and those with restrictive diets. If you suspect a deficiency or have a chronic condition affecting nutrient absorption, consult a registered dietitian or your primary care provider before starting any supplement regimen.
This article is for general informational and educational purposes only and does not constitute medical or dietary advice. Always consult a qualified healthcare professional for guidance specific to your health situation.
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Health & Wellness Editorial Team
Health & Wellness Editorial Team is the collective byline for our editorial team and contributor network. Articles published under this byline or an editorial pen name are researched, written, and reviewed according to our editorial standards for clarity, consistency, and independence before publication.
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