Vitamins & nutrition

Vitamins, minerals and nutrition explained

Clear, referenced guides to the nutrients your body needs — what each vitamin and mineral does, good food sources, and the signs of deficiency. 50 topics and growing.

Food groups

Fruit and VegetablesFruit and vegetables provide vitamins, minerals and fibre and help protect against many di… WholegrainsWholegrains keep all parts of the grain, giving more fibre and nutrients than refined grai… Dairy and AlternativesDairy foods and fortified alternatives are good sources of calcium and protein — choose lo… Oily FishOily fish such as salmon, mackerel and sardines are rich in omega-3 fats that support hear… Red and Processed MeatRed meat provides protein, iron and B12, but processed meat and large amounts of red meat … Pulses and BeansPulses such as beans, lentils and chickpeas are cheap, high in protein and fibre and low i… Nuts and SeedsNuts and seeds provide healthy fats, protein, fibre and minerals — a handful of unsalted o… EggsEggs are a good, affordable source of protein and nutrients and can be eaten regularly as … Plant-Based EatingA well-planned plant-based diet can be healthy and complete, but it needs attention to nut… Ultra-Processed FoodsUltra-processed foods are industrially made products often high in salt, sugar, fat and ad…

Macronutrients

ProteinProtein is a major nutrient the body uses to build and repair muscles, organs, skin and mo… FibreFibre is the part of plant foods the body cannot digest. It keeps the bowels healthy, help… CarbohydratesCarbohydrates are the body’s main source of energy. Starchy, higher-fibre carbs such as wh… Dietary FatsFat is an essential nutrient that provides energy and helps absorb some vitamins — but the… Saturated FatSaturated fat, found mainly in fatty meat, butter and cheese, can raise cholesterol and he… Unsaturated FatUnsaturated fats — from vegetable oils, nuts, seeds and oily fish — are the healthier fats… Trans FatsTrans fats are harmful fats, mostly from industrial processing, that raise heart disease r… SugarSugar provides energy but no other nutrients. Cutting down on "free sugars" — those added … Starchy FoodsStarchy foods such as potatoes, bread, rice and pasta should make up about a third of your…

Minerals

IronIron is a mineral needed to make haemoglobin, which carries oxygen in the blood. Low iron … CalciumCalcium is the mineral that builds and maintains strong bones and teeth. It also helps mus… MagnesiumMagnesium helps turn food into energy and keeps muscles, nerves and bones working normally… ZincZinc supports the immune system, wound healing, and normal growth. It is found in meat, sh… PotassiumPotassium helps control fluid balance, blood pressure and normal muscle and heart function… SodiumSodium, found mainly in salt, is needed in small amounts for fluid balance and nerve funct… IodineIodine is needed to make thyroid hormones, which control metabolism and are vital for a ba… SeleniumSelenium supports the immune system, reproduction and thyroid function, and acts as an ant… PhosphorusPhosphorus works with calcium to build strong bones and teeth and helps release energy fro… CopperCopper helps make red blood cells, keeps nerves and the immune system healthy, and helps t… ManganeseManganese helps make and activate enzymes involved in energy release and healthy bones. It… ChromiumChromium is a trace mineral that helps the body use insulin and process carbohydrate and f…

Diet & general nutrition

Omega-3 Fatty AcidsOmega-3 fatty acids are healthy fats, found especially in oily fish, that support heart an… Healthy Eating & a Balanced DietA balanced diet means eating a variety of foods in the right proportions — plenty of fruit… Water and HydrationWater is essential for life — aim for 6 to 8 glasses of fluid a day, more in hot weather o… Dietary CholesterolCholesterol in food has less effect on blood cholesterol for most people than saturated fa… Calories and EnergyCalories measure the energy food provides. Balancing the calories you eat with those you u…

Vitamins

Vitamin DVitamin D helps the body absorb calcium to keep bones, teeth and muscles healthy. Most is … Vitamin B12Vitamin B12 helps make red blood cells and keeps the nervous system healthy. It is found m… Vitamin CVitamin C helps protect cells, supports the immune system, and is needed to make collagen … Folate & Folic AcidFolate (and its supplement form, folic acid) helps make healthy red blood cells and is vit… Vitamin AVitamin A helps vision (especially in dim light), the immune system and healthy skin. Most… Vitamin EVitamin E is an antioxidant that helps protect cells and supports the immune system and sk… Vitamin KVitamin K is essential for blood clotting and helps keep bones healthy. It is found in gre… Vitamin B1Vitamin B1 (thiamine) helps the body release energy from food and keeps the nervous system… Vitamin B2Vitamin B2 (riboflavin) helps release energy from food and keeps skin, eyes and the nervou… Vitamin B3Vitamin B3 (niacin) helps release energy from food and keeps the nervous system and skin h… Vitamin B5Vitamin B5 (pantothenic acid) helps release energy from food. It is found in a very wide r… Vitamin B6Vitamin B6 helps the body use and store energy from protein and carbohydrate, and helps fo… Vitamin B7Vitamin B7 (biotin) helps the body make energy from food. It is found in many foods and al… CholineCholine is a nutrient, similar to a B vitamin, that supports the liver, brain and nervous …

See also

Healthy living · Conditions A–Z · Tests · First aid · Health calculators

Food first

What the evidence actually supports

Nutrition attracts more confident claims than almost any area of health, and most of them outrun the evidence. A few things are genuinely well supported, and they are unglamorous: an overall dietary pattern built on vegetables, fruit, wholegrains, pulses, and a moderate intake of unsaturated fats does more for long-term health than any single nutrient. Whole foods bring fibre and a mix of nutrients that an isolated supplement does not reproduce, which is why "food first" is the default in UK dietetic practice.

Supplements have real uses, but narrower ones than marketing suggests: correcting a demonstrated deficiency, meeting a raised requirement in pregnancy, covering a nutrient a particular diet genuinely lacks — vitamin B12 on a vegan diet, for example — or following specific national advice, such as taking a vitamin D supplement through the UK autumn and winter when sunlight is too weak for the skin to make enough. Outside those situations, more is not better, and some nutrients are actively harmful in excess.

Where a nutrient is also used as a prescribed treatment, we cover it twice on purpose: this section explains it as a dietary nutrient, and the linked treatment guide covers supplementation with its monitoring and interactions.

Reading a nutrition claim

Four questions that deflate most of them

  1. Was this measured in people, over a meaningful period? A great deal of nutrition marketing rests on cell studies or short trials measuring a blood marker rather than whether anyone lived longer or felt better — a surrogate endpoint.
  2. Is it a nutrient or a food? Findings about a nutrient inside a whole food frequently fail to reproduce when the nutrient is extracted into a capsule.
  3. How big is the effect in absolute terms? "Cuts your risk by 30%" means little without the starting risk. See absolute risk versus relative risk.
  4. Would it change what you actually eat? A real dietary change you can sustain beats an optimal one you abandon in a fortnight.

Each guide here covers what the nutrient does in the body, which foods supply it well, who is more likely to fall short, what deficiency looks like, and whether supplementing is supported. For applying this day to day see healthy living; for conditions where diet is part of management, the relevant condition guide sets out specifics.

Reference only. If you have a condition affecting what you can eat, are pregnant, or are considering supplements alongside prescribed medicines — several interact — speak to your GP, pharmacist or a registered dietitian rather than relying on general guidance.

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