Vitamins and Minerals
Tiny amounts, huge jobs. What the key vitamins and minerals do, where they come from in food, and why balance matters more than megadoses.
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What Are Vitamins and Minerals?
Vitamins and minerals belong to a category called micronutrients — nutrients needed in much smaller quantities than carbohydrates, protein or fat, but whose absence causes serious health problems. Together they participate in virtually every chemical reaction the body runs, from releasing energy from food to building bone and fighting infection.
The key distinction: vitamins are organic molecules (they contain carbon) and can be synthesised by plants or animals, including in small amounts by the human body itself. Minerals are inorganic elements — they come from the earth, move into plants and animals through the food chain, and cannot be made by living organisms. Both must mostly come from food.
Fat-Soluble Vitamins: A, D, E and K
Fat-soluble vitamins dissolve in fat, not water. This means they are best absorbed when eaten with some dietary fat, and they can be stored in fatty tissue and the liver — which is both an advantage (stores buffer against temporary shortfall) and a reason to avoid megadosing (toxic build-up is possible with A and D specifically).
| Vitamin | Key roles | Notable food sources |
|---|---|---|
| A (retinol) | Vision (especially night vision), immune function, skin cell turnover | Liver, oily fish, dairy; beta-carotene in orange/yellow vegetables is converted to vitamin A |
| D (calciferol) | Calcium absorption; bone development; immune modulation | Sunlight exposure; oily fish, egg yolks, fortified foods |
| E (tocopherol) | Antioxidant protecting cell membranes from damage | Nuts, seeds, vegetable oils, green leafy vegetables |
| K (phylloquinone / menaquinone) | Blood clotting; bone protein activation | Dark green vegetables (spinach, kale); K2 also found in fermented foods |
Vitamin D deserves special attention. The body synthesises it in the skin when exposed to UVB sunlight, but in regions with limited sunshine (or for people who spend little time outdoors), food and supplements become important. Vitamin D is involved not only in calcium absorption and bone health — covered further in the bones explained guide — but also in immune cell function.
Water-Soluble Vitamins: B Group and C
Water-soluble vitamins are not stored to the same degree as fat-soluble ones — excess is generally excreted in urine — so regular daily intake is important. They include the eight B vitamins and vitamin C.
- B1 (thiamine): Helps convert carbohydrates into energy; essential for nerve function.
- B2 (riboflavin): Energy metabolism; antioxidant roles.
- B3 (niacin): DNA repair; energy release; skin and nerve health.
- B5 (pantothenic acid): Synthesis of coenzyme A, central to metabolism.
- B6 (pyridoxine): Amino acid metabolism; neurotransmitter synthesis; immune function.
- B7 (biotin): Fat and glucose metabolism; often marketed for hair and nails, though evidence for supplementation in non-deficient individuals is limited.
- B9 (folate / folic acid): DNA synthesis and cell division; critical during pregnancy for neural tube development.
- B12 (cobalamin): Nerve function; red blood cell formation; DNA synthesis. Found almost exclusively in animal products, making supplementation important for vegans.
- C (ascorbic acid): Collagen synthesis; antioxidant; enhances iron absorption; supports immune response.
B vitamins work as a team — they are all involved in energy metabolism as coenzymes, helping enzymes do their work in converting food into usable energy.
Major Minerals
Minerals are divided by quantity needed: major (macro) minerals are needed in amounts greater than 100 mg per day; trace minerals are needed in smaller amounts. Both categories are equally important for health.
The major minerals include:
- Calcium: The most abundant mineral in the body — 99% is in bones and teeth. Also vital for muscle contraction and nerve signalling. Dairy, fortified plant milks, and leafy greens are good sources.
- Phosphorus: Works alongside calcium in bone structure; part of DNA and cell membranes; involved in energy storage (ATP). Found in protein-rich foods.
- Magnesium: Involved in over 300 enzyme reactions; supports muscle and nerve function, blood sugar regulation and bone development. Nuts, seeds, legumes and whole grains are good sources.
- Sodium: Regulates fluid balance and blood pressure; nerve and muscle function. The body needs relatively little; most people in developed countries consume considerably more than they need.
- Potassium: Balances sodium; essential for heart rhythm and muscle contraction. Found in vegetables, fruits, legumes and fish.
- Chloride: Fluid balance; component of stomach acid (hydrochloric acid).
- Sulphur: Part of certain amino acids and proteins; found in protein-containing foods.
Trace Minerals
Trace minerals are needed in milligram or microgram quantities, but they are no less essential. Key ones include:
| Mineral | Key function | Deficiency signs |
|---|---|---|
| Iron | Part of haemoglobin (oxygen transport in red blood cells) | Fatigue, pale skin, impaired immunity |
| Zinc | Immune function, wound healing, DNA synthesis, taste and smell | Slow wound healing, altered taste, hair loss |
| Iodine | Required to make thyroid hormones, which regulate metabolism | Goitre, hypothyroidism, developmental problems in pregnancy |
| Selenium | Antioxidant enzyme function; thyroid hormone metabolism | Muscle weakness, impaired immune function |
| Copper | Iron metabolism; connective tissue formation; nerve function | Anaemia, bone and connective tissue problems |
| Manganese | Bone formation; antioxidant enzyme activation; metabolism | Rare; linked to skeletal and reproductive issues |
| Chromium | Supports insulin action in glucose metabolism | Impaired glucose tolerance |
| Fluoride | Tooth enamel strength; bone density | Increased tooth decay |
Getting Enough Through Food
A varied diet built around whole, minimally processed foods is the most reliable way to obtain a full range of vitamins and minerals. No single food provides everything — variety is the strategy.
Particular groups face higher risk of specific deficiencies:
- Older adults are at risk for vitamin D, B12, calcium and magnesium deficiency.
- Vegans need to supplement vitamin B12 and pay attention to vitamin D, iodine, calcium, iron and zinc.
- Pregnant people have increased needs for folate, iron, iodine and vitamin D.
- Those in low-sunlight regions often have low vitamin D regardless of diet.
Use the vitamin reference tool to look up specific nutrients, and the nutrition planner to review whether your typical diet covers the main bases. For personalised advice — especially regarding supplementation — consult a registered dietitian or your doctor.
Micronutrients and Long-Term Health
Chronic micronutrient deficiencies are among the most common nutritional problems worldwide. Iron deficiency is the most prevalent, affecting hundreds of millions of people and causing anaemia that reduces work capacity and cognitive function. Iodine deficiency remains a major cause of preventable intellectual disability in young children in parts of the world where iodised salt is not widely used.
In higher-income settings, outright deficiency diseases are less common, but marginal deficiencies — where levels are low enough to impair function without causing obvious symptoms — are more widespread than many people realise. The immune system, mood, energy levels and bone health are all sensitive to micronutrient status. The connection between vitamins, minerals and immune function is explored further in the immune system guide.
The nutrition basics guide provides the broader context of how vitamins and minerals fit into overall dietary patterns.