Vitamins and Minerals: A Quick-Reference Guide to Key Micronutrients
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In this article
A concise lookup resource covering the main vitamins and minerals, their primary functions, food sources, and general deficiency signs.
What Are Micronutrients and Why Do They Matter?
Vitamins and minerals are collectively called micronutrients — nutrients the body needs in relatively small amounts but cannot function without. Unlike macronutrients like carbohydrates, proteins, and fats, micronutrients do not supply calories. Instead, they serve as essential co-factors in virtually every biological process: energy metabolism, immune defense, bone formation, nerve signaling, and cell repair.
Vitamins are organic compounds divided into two categories based on how the body stores them. Fat-soluble vitamins (A, D, E, K) are stored in fatty tissue and the liver; they can accumulate to excess if over-supplemented. Water-soluble vitamins (C and the eight B vitamins) are not stored in significant quantities and must be replenished regularly through food. Minerals are inorganic elements sourced entirely from diet and water — the body cannot synthesize them.
For a practical guide to identifying these nutrients on food packaging, see how to read a U.S. nutrition label.
Micronutrients
Vitamins and minerals needed by the body in small amounts to support essential biological functions. Unlike macronutrients, they provide no calories 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 eight B vitamins, which dissolve in water and are not stored in significant quantities. They must be replenished regularly through dietary sources.
Trace minerals
Minerals required in very small quantities — such as iron, zinc, iodine, and selenium — that are nonetheless essential for critical physiological processes including immune defense, thyroid function, and oxygen transport.
Bioavailability
The proportion of a nutrient that the body actually absorbs and uses after ingestion. Bioavailability varies by food source, preparation method, and the presence of other nutrients (e.g., vitamin C enhances non-heme iron absorption).
Recommended Dietary Allowance (RDA)
The average daily intake level sufficient to meet the nutrient requirements of nearly all healthy individuals in a particular life stage and sex group, as established by the National Academies of Sciences, Engineering, and Medicine.
Key Vitamins: Functions, Sources, and Deficiency Signs
The table below summarizes the primary fat-soluble and water-soluble vitamins. It is intended as a general educational reference, not a personal dietary prescription. Needs vary by age, health status, and other individual factors — consult a registered dietitian or healthcare provider for personalized guidance.
| Total essential vitamins | 13 (National Institutes of Health, Office of Dietary Supplements) |
| Fat-soluble vitamins | 4 (A, D, E, K) |
| Water-soluble vitamins | 9 (C and 8 B vitamins) |
| Most common global deficiency | Iron deficiency (World Health Organization) |
| Vitamin D deficiency prevalence (U.S. adults) | ~35% (National Health and Nutrition Examination Survey (NHANES)) |
| Folate critical window | First 28 days of pregnancy (CDC folic acid guidance) |
| Vitamin | Primary Function | Main Food Sources | Common Deficiency Signs |
|---|---|---|---|
| A (Retinol / Beta-carotene) | Vision, immune function, skin integrity | Liver, dairy, eggs; beta-carotene in orange/yellow produce and leafy greens | Night blindness, dry skin, frequent infections |
| D | Calcium absorption, bone health, immune modulation | Fatty fish, fortified dairy and plant milks, egg yolks; sunlight exposure | Bone pain, muscle weakness, increased infection risk |
| E | Antioxidant protection, immune support | Nuts, seeds, vegetable oils, wheat germ | Rare; nerve damage and muscle weakness in severe cases |
| K | Blood clotting, bone metabolism | Leafy greens (kale, spinach), broccoli, fermented foods | Impaired clotting, easy bruising |
| C | Collagen synthesis, antioxidant, immune support, iron absorption | Citrus fruits, bell peppers, broccoli, strawberries | Fatigue, bleeding gums, slow wound healing (scurvy in severe cases) |
| B1 (Thiamine) | Energy metabolism, nerve function | Whole grains, legumes, pork | Fatigue, nerve pain, heart complications (beriberi) |
| B2 (Riboflavin) | Energy production, red blood cell formation | Dairy, eggs, lean meats, leafy greens | Cracked lips, sore throat, skin rash |
| B3 (Niacin) | DNA repair, energy metabolism | Poultry, fish, peanuts, fortified cereals | Skin rash, diarrhea, dementia (pellagra) |
| B6 | Protein metabolism, neurotransmitter synthesis | Poultry, fish, potatoes, bananas | Anemia, depression, confusion |
| B9 (Folate) | DNA synthesis, red blood cell formation, fetal neural development | Leafy greens, legumes, fortified grains | Anemia, fatigue; neural tube defects in early pregnancy |
| B12 | Nerve function, red blood cell production, DNA synthesis | Animal products (meat, fish, dairy, eggs); fortified plant foods | Fatigue, nerve damage, megaloblastic anemia |
A Note on Supplement Use
Dietary supplements can help address specific, clinically confirmed deficiencies, but they are not universally necessary and carry their own risks — particularly for fat-soluble vitamins, which can accumulate to harmful levels. The U.S. Food and Drug Administration does not evaluate supplements for safety or efficacy before they reach the market. Always discuss supplementation with a healthcare provider before starting a new regimen.
Key Minerals: What the Body Needs and Where to Find It
Minerals are divided into 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). The following covers the most clinically significant ones.
| Mineral | Primary Function | Main Food Sources | Common Deficiency Signs |
|---|---|---|---|
| Calcium | Bone and tooth structure, muscle contraction, nerve signaling | Dairy, fortified plant milks, tofu, leafy greens, canned fish with bones | Muscle cramps, brittle bones, osteoporosis risk |
| Magnesium | Enzyme reactions, energy production, muscle and nerve function | Nuts, seeds, whole grains, legumes, dark leafy greens | Muscle twitches, fatigue, irregular heartbeat |
| Iron | Oxygen transport (hemoglobin), energy metabolism | Red meat, poultry, fish; plant sources: lentils, beans, fortified cereals (pair with vitamin C) | Fatigue, pale skin, impaired concentration (iron-deficiency anemia) |
| Zinc | Immune function, wound healing, protein synthesis, taste/smell | Oysters, red meat, poultry, beans, nuts, whole grains | Delayed wound healing, hair loss, impaired immunity |
| Potassium | Fluid balance, nerve signals, muscle function, blood pressure regulation | Bananas, potatoes, beans, leafy greens, dairy | Muscle weakness, cramps, irregular heartbeat |
| Iodine | Thyroid hormone production, metabolism regulation | Iodized salt, seafood, dairy | Goiter, hypothyroidism, fatigue |
| Selenium | Antioxidant defense, thyroid function | Brazil nuts, seafood, poultry, whole grains | Muscle weakness, impaired immunity |
Because nutrient needs shift considerably across the lifespan, see how dietary needs change from childhood through older adulthood for age-specific context.
~35%
U.S. adults with insufficient vitamin D
According to NHANES data, approximately one in three U.S. adults has blood levels of vitamin D considered below optimal by many clinical standards.
2 billion
People affected by micronutrient deficiencies globally
The World Health Organization estimates that deficiencies in iron, vitamin A, iodine, and other micronutrients affect roughly two billion people worldwide.
B12
Most common deficiency in plant-based eaters
Because B12 is found almost exclusively in animal products, individuals following strict vegan diets are at high risk without supplementation or fortified foods, per dietary research.
Getting Enough Through Food — and When to Consider More
For most generally healthy adults, a varied diet centered on whole foods — vegetables, fruits, legumes, whole grains, lean proteins, and dairy or fortified alternatives — provides adequate amounts of most vitamins and minerals. No single food group covers every micronutrient, which is one of the strongest evidence-based arguments for dietary variety.
Certain populations face elevated deficiency risks and may warrant closer monitoring or supplementation under medical supervision: people who are pregnant or breastfeeding (especially folate, iron, iodine, and choline needs), older adults (vitamin D, B12, calcium), individuals following strict plant-based diets (B12, iron, zinc, iodine, calcium, omega-3s), and those with conditions affecting nutrient absorption.
If you are beginning to build healthier eating habits, focusing first on food variety typically covers micronutrient needs better than supplementing a poor diet. Supplements can help fill specific, clinically identified gaps — but they are not a substitute for a balanced pattern of eating. A registered dietitian or physician can help identify genuine gaps through dietary assessment or blood testing.
A useful practical step is a pantry audit to see whether your everyday staples support adequate micronutrient coverage.
This article provides general nutrition information for educational purposes only and is not a substitute for personalized medical or dietary advice. Consult a qualified healthcare professional before making changes to your diet or supplement regimen.
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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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