What Vitamins and Minerals Actually Are
Vitamins and minerals are micronutrients — compounds your body requires in relatively small amounts but cannot produce in sufficient quantities on its own. Unlike macronutrients (carbohydrates, proteins, and fats), micronutrients provide no calories. Instead, they serve as essential co-factors in hundreds of biological processes, from energy metabolism to immune signaling to bone maintenance. For a fuller picture of how macronutrients and micronutrients work together, see our macronutrient deep-dive.
Vitamins fall into two broad categories: fat-soluble (A, D, E, K), which are stored in body fat and liver tissue, and water-soluble (C and the B vitamins), which must be replenished more regularly because the body excretes excess amounts. Minerals are inorganic elements; macrominerals such as calcium and magnesium are needed in larger amounts, while trace minerals such as iron and zinc are needed in smaller quantities but are no less critical. For a deeper look at how these nutrients function inside the body, visit Vitamins and Minerals: What They Actually Do in Your Body.
Micronutrient
A vitamin or mineral required by the body in small amounts to support normal physiological function. Unlike macronutrients, micronutrients do not supply calories.
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 intake from supplements can potentially reach harmful levels over time.
Water-Soluble Vitamins
Vitamin C and the eight B vitamins, which dissolve in water and are not stored in significant amounts. The body regularly excretes excess amounts in urine, so consistent dietary intake is important.
RDA (Recommended Dietary Allowance)
The average daily dietary intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a particular life stage and sex group, as established by the National Academies of Sciences.
Adequate Intake (AI)
A reference value used when evidence is insufficient to establish a firm RDA. It represents an approximation of the intake that appears to sustain adequate nutritional status.
Trace Minerals
Essential minerals needed by the body in very small quantities — generally less than 100 mg per day. Examples include iron, zinc, iodine, and selenium.
Macrominerals
Essential minerals required in larger daily amounts (100 mg or more), including calcium, magnesium, and potassium. They play structural and regulatory roles throughout the body.
Key Vitamins: Roles, Sources, and General Guidance
The table below summarizes the major vitamins, their primary functions, and common food sources. Daily intake figures reflect general adult reference values published by the National Institutes of Health (NIH) Office of Dietary Supplements and should not be interpreted as personal prescriptions. Always consult a qualified healthcare professional before making significant changes to your diet or starting any supplement regimen.
| Vitamin | Primary Role | Common Food Sources | General Adult Reference (RDA/AI) |
|---|---|---|---|
| A | Vision, immune function, cell growth | Liver, dairy, sweet potato, carrots, leafy greens | 700–900 mcg RAE/day |
| D | Calcium absorption, bone health, immune support | Fatty fish, fortified dairy, egg yolks, sunlight synthesis | 600–800 IU/day (15–20 mcg) |
| E | Antioxidant protection, immune function | Sunflower seeds, almonds, vegetable oils, spinach | 15 mg/day |
| K | Blood clotting, bone metabolism | Kale, broccoli, spinach, fermented foods | 90–120 mcg/day |
| C | Collagen synthesis, antioxidant, iron absorption | Citrus fruits, bell peppers, strawberries, broccoli | 75–90 mg/day |
| B1 (Thiamin) | Energy metabolism, nerve function | Whole grains, legumes, pork | 1.1–1.2 mg/day |
| B2 (Riboflavin) | Energy production, cellular function | Dairy, eggs, lean meats, almonds | 1.1–1.3 mg/day |
| B3 (Niacin) | DNA repair, energy metabolism | Poultry, tuna, peanuts, whole grains | 14–16 mg NE/day |
| B6 | Protein metabolism, neurotransmitter synthesis | Poultry, fish, potatoes, bananas | 1.3–1.7 mg/day |
| B9 (Folate) | DNA synthesis, red blood cell formation | Legumes, leafy greens, fortified grains | 400 mcg DFE/day |
| B12 | Nerve function, red blood cell formation | Meat, fish, dairy, fortified plant milks | 2.4 mcg/day |
A Note on Supplements vs. Food Sources
Whole foods deliver vitamins alongside fiber, antioxidants, and other compounds that may work synergistically in ways isolated supplements cannot fully replicate. Most major nutrition authorities, including the Dietary Guidelines for Americans, recommend meeting nutrient needs primarily through food. If you suspect a deficiency or belong to a higher-risk group — such as older adults, pregnant individuals, or those with restricted diets — speak with a healthcare professional before starting any supplement.
Key Minerals: Roles, Sources, and General Guidance
Minerals support structural roles (bones, teeth) as well as regulatory functions (fluid balance, muscle contraction, oxygen transport). The values below are general adult reference figures from NIH guidelines.
| Number of Essential Vitamins | 13 (NIH Office of Dietary Supplements) |
| Fat-Soluble Vitamins | A, D, E, K |
| Most Common Micronutrient Deficiency Worldwide | Iron deficiency (World Health Organization) |
| Vitamin D Synthesis Source | UVB sunlight exposure on skin (NIH Office of Dietary Supplements) |
| B Vitamins Count | 8 (B1, B2, B3, B5, B6, B7, B9, B12) |
| Vitamin C Also Aids | Absorption of non-heme (plant-based) iron |
| Mineral | Primary Role | Common Food Sources | General Adult Reference (RDA/AI) |
|---|---|---|---|
| Calcium | Bone and tooth structure, muscle contraction, nerve signaling | Dairy, fortified plant milks, kale, tofu | 1,000–1,200 mg/day |
| Magnesium | Enzyme activity, energy production, muscle and nerve function | Nuts, seeds, whole grains, dark chocolate | 310–420 mg/day |
| Potassium | Fluid balance, blood pressure regulation, heart rhythm | Bananas, potatoes, beans, leafy greens | 2,600–3,400 mg/day |
| Iron | Oxygen transport via hemoglobin | Red meat, legumes, fortified cereals, spinach | 8–18 mg/day (higher for menstruating adults) |
| Zinc | Immune function, wound healing, protein synthesis | Oysters, beef, pumpkin seeds, legumes | 8–11 mg/day |
| Iodine | Thyroid hormone production, metabolism regulation | Iodized salt, seafood, dairy | 150 mcg/day |
| Selenium | Antioxidant defense, thyroid function | Brazil nuts, tuna, eggs, whole grains | 55 mcg/day |
Eating a varied diet centered on whole foods — vegetables, fruits, legumes, whole grains, lean proteins, and dairy or fortified alternatives — remains the most evidence-supported strategy for meeting micronutrient needs across most healthy adults. Building this foundation aligns well with the everyday habits described in our Healthy Daily Habits reference guide.
This article is for general informational and educational purposes only and does not constitute medical advice. Reference values cited are general population figures; individual needs vary based on age, sex, health status, and other factors. Consult a qualified healthcare professional before making changes to your diet or supplement routine, especially if you have a medical condition, are pregnant, or care for a child or older adult.
