Vitamins and Minerals: A Quick-Reference Guide to What They Do

Why Vitamins and Minerals Matter

Your body cannot manufacture most vitamins and minerals on its own — it depends on food (and, in some cases, sunlight) to get them. These micronutrients are distinct from macronutrients like protein, fat, and carbohydrates: you need them in smaller amounts, but their roles are no less critical. They enable thousands of biochemical processes, from converting food into energy to building bone, clotting blood, and supporting immune defenses.

Persistent shortfalls — even modest ones — can interfere with how you feel and function long before a clinical deficiency is diagnosed. Understanding what each nutrient does, and where to find it, is a practical first step toward a more informed approach to eating. For a broader foundation, see our guide to everyday nutrition for US adults.

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

Fat-soluble vitamins are stored in body fat and the liver, which means they accumulate over time. This storage capacity is useful — you don't need to consume them every day — but it also means excessive supplementation can lead to toxicity. Always speak with a healthcare provider before taking high-dose fat-soluble supplements.

• Vitamin A: Supports vision (especially in low light), immune function, and skin cell turnover. Found in liver, dairy, eggs, and orange-yellow produce like carrots and sweet potatoes. Also available as beta-carotene, a precursor found in plants.
• Vitamin D: Regulates calcium absorption and is essential for bone health. The skin synthesizes it from sunlight; dietary sources include fatty fish, fortified milk, and egg yolks. Deficiency is widespread, particularly in northern latitudes and among people with limited sun exposure.
• Vitamin E: Acts as an antioxidant, protecting cell membranes from oxidative damage. Found in nuts, seeds, vegetable oils, and leafy greens.
• Vitamin K: Required for blood clotting and bone metabolism. Vitamin K1 comes mainly from leafy vegetables; K2 is found in fermented foods and some animal products. People taking blood-thinning medications should consult a provider before changing K intake.

Water-Soluble Vitamins (C and the B Vitamins)

Water-soluble vitamins are not stored in significant quantities — excess amounts are generally excreted in urine. This means you need a more consistent supply through diet, and the risk of toxicity from food sources is low (though high-dose supplements are a different matter).

• Vitamin C: Essential for collagen synthesis, wound healing, and immune support. Also enhances iron absorption from plant foods. Found in citrus fruits, bell peppers, strawberries, and broccoli.
• B1 (Thiamine): Converts carbohydrates to energy; supports nerve function. Found in whole grains, legumes, and pork.
• B2 (Riboflavin): Involved in energy metabolism and cellular repair. Found in dairy, eggs, lean meats, and leafy greens.
• B3 (Niacin): Supports energy production and DNA repair. Found in poultry, fish, peanuts, and whole grains.
• B6 (Pyridoxine): Required for protein metabolism and neurotransmitter synthesis. Found in poultry, fish, potatoes, and bananas.
• B9 (Folate/Folic Acid): Critical for DNA synthesis and cell division; especially important before and during pregnancy to reduce neural tube defect risk. Found in dark leafy greens, legumes, and fortified grains.
• B12 (Cobalamin): Essential for nerve health and red blood cell formation. Found almost exclusively in animal products; people following vegan diets should discuss supplementation with a provider.
• Biotin and Pantothenic Acid: Both support energy metabolism and are widely distributed across many foods; deficiencies are uncommon in typical diets.

When reviewing packaged foods, the % Daily Value column on a nutrition label shows how much a serving contributes toward recognized intake targets — our guide to reading nutrition labels explains what those numbers really mean.

Key Minerals: Macro and Trace

Minerals are divided into macrominerals (needed in larger amounts) and trace minerals (needed in tiny amounts, but still essential).

Macrominerals

• Calcium: The primary mineral in bones and teeth; also involved in muscle contraction and nerve signaling. Found in dairy, fortified plant milks, tofu, and leafy greens like kale.
• Magnesium: Participates in over 300 enzymatic reactions, including energy production and muscle relaxation. Found in nuts, seeds, whole grains, and dark chocolate.
• Potassium: Regulates fluid balance, blood pressure, and nerve impulses. Found in bananas, potatoes, beans, and leafy greens.
• Phosphorus: Partners with calcium in bone structure and supports energy storage. Found in dairy, meat, fish, and legumes.

Key Trace Minerals

• Iron: Central to hemoglobin, which carries oxygen in the blood. Heme iron from red meat and poultry is more readily absorbed; non-heme iron from plants is better absorbed alongside vitamin C.
• Zinc: Supports immune function, wound healing, and taste perception. Found in shellfish, red meat, legumes, and pumpkin seeds.
• Iodine: Required for thyroid hormone production, which regulates metabolism. Found in iodized salt, seafood, and dairy.
• Selenium: An antioxidant mineral that supports thyroid function. Found in Brazil nuts, seafood, and whole grains.

Planning your grocery trips with micronutrients in mind doesn't have to be complicated. Our practical grocery shopping guide offers a straightforward checklist to keep variety and nutrition on track.

This article is for general informational purposes only and is not a substitute for professional medical or dietary advice. If you have questions about your specific nutrient needs, speak with a qualified healthcare provider or registered dietitian.