list of all vitamins, their types, and their primary functions

A vitamin is an organic compound the body needs in small amounts for normal function but generally cannot make in sufficient quantity itself, which means it has to come from the diet or, in one case, from sunlight exposure.

That last clause is what separates a vitamin from other nutrients. Carbohydrates, fats and proteins supply energy and structure in large quantities. Vitamins do not supply energy. They act as cofactors and precursors in the chemical reactions that release energy, build tissue, form blood cells and maintain nerves, vision, skin and bone.

The word “essential” in nutrition has a technical meaning: the body cannot synthesise enough of the compound to meet its needs. All 13 vitamins listed on this page are essential in that sense. Vitamin D is the notable partial exception, since the skin synthesises it on exposure to ultraviolet B radiation, which is why it is sometimes called the sunshine vitamin.

There are 13 essential vitamins: A, C, D, E, K, and eight vitamins in the B group, namely B1, B2, B3, B5, B6, B7, B9 and B12.

The gaps in the B numbering are historical. Compounds once numbered B4, B8, B10 and others were later found either not to be essential to humans or to be the same substance as something already named, so the numbers were retired rather than reassigned. The surviving eight are collectively called the B-complex because they were originally isolated together and often occur together in the same foods.

Choline is sometimes discussed alongside the B vitamins as an essential nutrient, but it is not formally classified as a vitamin. Vitamin K exists in more than one natural form, most commonly phylloquinone from plants and menaquinone from bacterial synthesis and fermented foods.

The single most useful division in this subject is solubility, because solubility determines how a vitamin is absorbed, whether the body stores it, and how often it needs replacing.

Fat soluble vitamins are A, D, E and K. They dissolve in fat, are absorbed alongside dietary fat, and are stored in the liver and in fatty tissue. Because they are stored, intake does not need to be matched day by day. For the same reason, excess intake from concentrated sources can accumulate.

Water soluble vitamins are vitamin C and the eight B-complex vitamins. They dissolve in water, are absorbed more directly, and are largely not stored in the body, with vitamin B12 as the significant exception since the liver holds a substantial reserve. Surplus amounts are generally excreted in urine, which is why intake matters on a more regular basis.

Solubility also affects cooking. Water soluble vitamins can leach into cooking water and are more sensitive to heat and prolonged storage; fat soluble vitamins survive water better but need some dietary fat present for absorption.

The table below is the reference version of this article. It lists every essential vitamin, its chemical name, its solubility class, its principal roles in the body and common food sources. Functions are stated as physiological roles, not as health claims: no vitamin listed here is presented as treating or preventing any disease.

Vitamin A exists as preformed retinoids in animal foods and as carotenoid precursors in plants, which the body converts as needed. Its best-understood role is in the retina, where retinal is a component of the pigment that allows vision in low light. It also maintains the epithelial linings of the eye, gut and airways.

Vitamin D functions more like a hormone than a classical vitamin. It is synthesised in the skin under ultraviolet B exposure, then converted in the liver and kidneys to its active form, which regulates calcium and phosphorus absorption from the gut. It has a much fuller treatment in vitamin D in more detail.

Vitamin E is a family of compounds that act as fat-soluble antioxidants, protecting the lipids in cell membranes from oxidative damage. In Indian diets it comes largely from cooking oils, seeds and nuts.

Vitamin K is required for the liver to produce several clotting factors, which is why it is central to normal blood coagulation. It also participates in bone protein metabolism. Anyone taking anticoagulant medication should discuss vitamin K intake with their treating doctor, because the interaction is clinically significant and is a matter for a physician, not an article.

The eight B vitamins are grouped together because they were isolated from the same sources and because most of them act as coenzymes in energy metabolism. They are not interchangeable and each has distinct roles.

Three of them have a particular connection to blood. Vitamin B9 (folate) and vitamin B12 (cobalamin) are both required for normal red blood cell production, and inadequate status of either is a recognised cause of a form of anaemia. Vitamin B6 participates in haemoglobin synthesis. This matters in the Indian context, where anaemia is a recognised public health priority addressed through National Health Mission programming including Anaemia Mukt Bharat.

Vitamin B12 deserves a specific note for readers following vegetarian and vegan diets, which are common across India. B12 is not naturally present in unfortified plant foods; dietary sources are animal foods and fortified products. Anyone whose diet excludes those sources should raise the question with a qualified physician, who can decide whether testing is appropriate. That decision, and anything that follows from it, belongs to a doctor.

Vitamin B1 (thiamine), B2 (riboflavin), B3 (niacin) and B5 (pantothenic acid) are the core energy-metabolism cofactors, each entering a different step of the pathway that converts food into usable energy. Vitamin B7 (biotin) works in fatty acid synthesis and is popularly associated with hair, skin and nails because of its role in keratin structure.

Vitamin C, or ascorbic acid, is the most widely known water soluble vitamin. Its central biochemical role is as a cofactor in collagen synthesis, which makes it structurally important for skin, blood vessels, gums, bone and connective tissue.

It also acts as an antioxidant and substantially improves the absorption of non-haem iron, the form of iron found in plant foods. That interaction is why a citrus fruit or an amla alongside a pulse-based meal is a long-standing feature of Indian dietary practice.

Humans, unlike most mammals, cannot synthesise vitamin C, which is why it must come from the diet. It is heat sensitive and water soluble, so prolonged cooking reduces the amount retained in food.

This section is about who should raise the question with a physician. It is not a list of people who need supplements, and nothing here should be read as a recommendation to take any product.

• People following diets that exclude whole food groups, including strict vegetarian and vegan diets, particularly with respect to vitamin B12.
• People who are pregnant, planning a pregnancy or breastfeeding. Nutritional requirements change and are managed by an obstetrician, not self-assessed.
• Older adults, in whom absorption of some nutrients changes with age and with commonly prescribed medications.
• People with gastrointestinal conditions or after gastrointestinal surgery, where absorption may be affected.
• People with limited sunlight exposure, including indoor workers, people who cover most of the skin and residents of areas with high air pollution, in relation to vitamin D.
• People taking long-term medication, since several common medicines interact with specific vitamins. Anyone on anticoagulants in particular should not change vitamin K intake without medical advice.
• Infants, children and adolescents, whose requirements are managed by a paediatrician against growth references.

The correct next step for any of these groups is a consultation, and if the doctor considers it appropriate, a laboratory blood test. Vitamin status cannot be assessed from symptoms alone, and it cannot be assessed from a screening kiosk.

No. Clinics On Cloud Health ATMs and Health Kiosks do not measure vitamin levels. There is no vitamin A, vitamin D, vitamin B12, folate or vitamin C assay in the parameter set, and this article should not be read as implying one.

Vitamin status is assessed by laboratory blood assays ordered and interpreted by a doctor. Those are venous blood tests processed in an accredited laboratory. A screening kiosk is a different instrument with a different purpose.

Stating this plainly is deliberate. Clinics On Cloud is a preventive screening infrastructure company, not a diagnostic laboratory, and a reader who arrives here searching for vitamin information deserves an accurate answer about what the product does and does not do.

A Health ATM is a self-service screening station that measures a defined set of clinical parameters in a single session and returns a report without requiring a skilled operator. The Clinics On Cloud Health ATM covers 65+ clinical parameters across 14 specialties, with a full checkup in 10 minutes.

The parameter closest to the nutritional questions on this page is anaemia screening, which sits within the anaemia and kidney group. Anaemia has multiple causes, some nutritional and some not, and a screening result is an indication to investigate rather than an answer in itself. Where a reading is flagged, an integrated telemedicine consultation is available from the kiosk, and the appropriate outcome is a physician’s assessment and, where indicated, laboratory testing.

The wider set includes general health and body composition, cardiac parameters including ECG, blood pressure and lipid profile, random blood sugar and HbA1c, urine analysis, pulmonary function, vision, hearing, dental and oral screening, dermatology, mental health questionnaires and rapid infectious disease tests. The full breakdown is in clinical parameters and tests offered by a health kiosk and the 19 general health parameters a health checkup machine covers.

Across the Clinics On Cloud network, 12M+ patients have been screened and 2 lakh+ abnormalities have been detected and routed for early intervention, through 3,500+ installations in 200+ cities and 8+ countries as of 2026.

For a single-nutrient deep dive, read vitamin D in more detail. For what a screening station genuinely measures, read what a Health ATM is. To plan a workplace, community or CSR screening programme, call +91 8999 073 447, Monday to Saturday, 9:00 to 18:00 IST, or email sales@clinicsoncloud.com.