| Total essential vitamins | 13 (National Institutes of Health, Office of Dietary Supplements) |
| Fat-soluble vitamins | A, D, E, K |
| Water-soluble vitamins | C plus 8 B vitamins |
| Most common deficiency in the US | Vitamin D (National Health and Nutrition Examination Survey (NHANES)) |
| Vitamin C content in one red bell pepper | ~190 mg (over 2× the adult RDA) (USDA FoodData Central) |
| Iron absorption boost | Up to 3× higher when paired with vitamin C (American Journal of Clinical Nutrition) |
What Vitamins and Minerals Actually Do
Vitamins and minerals are classified as micronutrients — nutrients your body needs in relatively small amounts but cannot function well without. Unlike protein, carbohydrates, and fat, micronutrients provide no calories; instead, they act as cofactors that enable thousands of biological processes, from converting food into usable energy to keeping your immune system ready to respond. For a broader look at how macronutrients fit into the picture, see our plain-language guide to macronutrients.
Vitamins fall into two groups based on how the body handles them:
- Fat-soluble vitamins (A, D, E, K) are stored in body fat and the liver, meaning they accumulate over time. This makes deficiency less common on a reasonably varied diet, but also means excessive supplementation can lead to toxicity.
- Water-soluble vitamins (C and the eight B vitamins) are not stored in significant amounts and are excreted in urine. They need to be replenished more consistently through food.
Minerals are inorganic elements. Major minerals — including calcium, magnesium, potassium, and sodium — are needed in larger amounts. Trace minerals — including iron, zinc, selenium, and iodine — are required in much smaller quantities but are still essential.
Micronutrient
Vitamins and minerals that the body requires in small quantities to function properly. They do not provide calories but play critical roles in metabolism, immunity, and cell function.
Fat-soluble vitamin
Vitamins (A, D, E, and K) that dissolve in fat and are stored in body tissues. Because they accumulate, excessive intake from supplements can cause toxicity over time.
Water-soluble vitamin
Vitamins (C and the B-complex group) that dissolve in water and are not stored in the body for long. Excess amounts are typically excreted in urine, so regular dietary intake is important.
Trace mineral
A mineral the body needs in very small amounts — typically less than 100 mg per day — such as iron, zinc, selenium, and iodine. Deficiency can still have significant health consequences.
Bioavailability
The proportion of a nutrient that the body actually absorbs and uses. Factors like food preparation, other nutrients present, and individual gut health all influence bioavailability.
Dietary Reference Intake (DRI)
A set of reference values developed by the National Academies of Sciences that guide how much of each nutrient is adequate, sufficient, or tolerable for most healthy people.
Key Vitamins: What They Do and Where to Find Them
The table below summarizes the most commonly discussed vitamins, their primary roles in the body, and reliable food sources. This is general reference information — not a guide for self-diagnosing deficiencies or selecting supplements. Always consult a healthcare provider before making significant changes to your diet or starting a supplement regimen.
| Vitamin | Primary Role | Common Food Sources |
|---|---|---|
| Vitamin A | Vision, immune function, skin cell turnover | Liver, dairy, eggs; beta-carotene in sweet potatoes, carrots, spinach |
| Vitamin C | Antioxidant, collagen synthesis, immune support | Bell peppers, citrus fruit, broccoli, strawberries |
| Vitamin D | Calcium absorption, bone health, immune modulation | Fatty fish, fortified milk, egg yolks; skin synthesis from sunlight |
| Vitamin E | Antioxidant, cell membrane protection | Sunflower seeds, almonds, vegetable oils, spinach |
| Vitamin K | Blood clotting, bone mineralization | Leafy greens (kale, collards), broccoli, fermented foods |
| B1 (Thiamine) | Energy metabolism, nerve function | Whole grains, pork, legumes |
| B9 (Folate) | DNA synthesis, cell division; critical in pregnancy | Lentils, leafy greens, fortified cereals, asparagus |
| B12 | Nerve health, red blood cell formation | Meat, fish, dairy, eggs; fortified plant milks |
People following plant-based diets may want to discuss B12 and vitamin D intake specifically with a registered dietitian, as these are harder to obtain without animal products or sunlight. You can also learn how these nutrients appear on food packaging in our guide to reading a nutrition label.
| Total essential vitamins | 13 (National Institutes of Health, Office of Dietary Supplements) |
| Fat-soluble vitamins | A, D, E, K |
| Water-soluble vitamins | C plus 8 B vitamins |
| Most common deficiency in the US | Vitamin D (National Health and Nutrition Examination Survey (NHANES)) |
| Vitamin C content in one red bell pepper | ~190 mg (over 2× the adult RDA) (USDA FoodData Central) |
| Iron absorption boost | Up to 3× higher when paired with vitamin C (American Journal of Clinical Nutrition) |
Key Minerals: Roles and Reliable Sources
Minerals work alongside vitamins and macronutrients to keep bones strong, regulate fluid balance, carry oxygen in the blood, and support muscle and nerve signaling.
| Mineral | Primary Role | Common Food Sources |
|---|---|---|
| Calcium | Bone and tooth structure, muscle contraction, nerve signaling | Dairy, fortified plant milks, tofu (set with calcium), sardines, leafy greens |
| Iron | Oxygen transport in red blood cells | Red meat, shellfish, lentils, spinach (pair with vitamin C to improve absorption) |
| Magnesium | Enzyme reactions, muscle and nerve function, blood sugar regulation | Nuts, seeds, whole grains, dark leafy greens, legumes |
| Potassium | Blood pressure regulation, fluid balance, muscle contractions | Bananas, potatoes, beans, yogurt, avocados |
| Zinc | Immune function, wound healing, protein synthesis | Oysters, beef, pumpkin seeds, chickpeas, dairy |
| Iodine | Thyroid hormone production, metabolism regulation | Iodized salt, seafood, dairy, eggs |
| Selenium | Antioxidant defense, thyroid function | Brazil nuts, tuna, eggs, sunflower seeds |
For a complementary overview of these same nutrients in a different format, see Micronutrients at a Glance. And to understand how federal guidance shapes daily intake recommendations, our article on making sense of dietary guidelines offers practical context.
This article is for general informational purposes only and is not a substitute for professional medical or dietary advice. Speak with a qualified healthcare provider about your individual nutritional needs.