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Vitamin

A nutrient that the body needs in small amounts to function and stay healthy.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Vitamins

A nutrient that the body needs in small amounts to function and stay healthy. Sources of vitamins are plant and animal food products and dietary supplements. Some vitamins are made in the human body from food products.

Vitamins are either fat-soluble (can dissolve in fats and oils) or water-soluble (can dissolve in water). Excess fat-soluble vitamins are stored in the body's fatty tissue, but excess water-soluble vitamins are removed in the urine. Examples are vitamin A, vitamin C, and vitamin E. NIH - National Cancer Institute

What works? Research summarized

Evidence reviews

Antioxidant vitamins and mineral supplements to slow down the progression of age‐related macular degeneration

Age‐related macular degeneration (AMD) is a condition affecting the central area of the retina (back of the eye). The retina can deteriorate with age and some people get lesions that can lead to loss of central vision. It has been suggested that progression of the disease may be slowed down in people who eat a diet rich in antioxidant vitamins (carotenoids, vitamins C and E) or minerals (selenium and zinc). We identified 13 randomised controlled trials that included 6150 participants; five trials based in the USA, two in the UK, two trials in Austria, and one trial in each of a further four countries (Australia, China, Italy and Switzerland). The review of trials found that supplementation with antioxidants and zinc may be of modest benefit in people with AMD. This was mainly seen in one large trial that followed up participants for an average of six years. The other smaller trials with shorter follow‐up do not provide evidence of any benefit. Large well‐conducted trials in a range of populations and with different nutritional status are required. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed.

Vitamins for epilepsy

No evidence that folic acid, thiamine, vitamin D or vitamin E improve seizure control or prevent side effects for people with epilepsy.

Antioxidant vitamins and mineral supplements to prevent the development of age‐related macular degeneration

Age‐related macular degeneration (AMD) is a condition affecting the central area of the retina (back of the eye). The retina can deteriorate with age and some people get lesions that can lead to loss of central vision. Some studies have suggested that people who eat a diet rich in antioxidant vitamins (carotenoids, vitamins C and E) or minerals (selenium and zinc) may be less likely to get AMD. The authors identified four large, high‐quality randomised controlled trials which included 62,520 people. The trials were conducted in Australia, Finland and the USA and investigated the effects of vitamin E and beta‐carotene supplementation. These trials provide evidence that taking vitamin E and beta‐carotene supplements is unlikely to prevent the onset of AMD. There was no evidence for other antioxidant supplements and commonly marketed combinations. Although generally regarded as safe, vitamin supplements may have harmful effects and clear evidence of benefit is needed before they can be recommended.

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Summaries for consumers

Antioxidant vitamins and mineral supplements to slow down the progression of age‐related macular degeneration

Age‐related macular degeneration (AMD) is a condition affecting the central area of the retina (back of the eye). The retina can deteriorate with age and some people get lesions that can lead to loss of central vision. It has been suggested that progression of the disease may be slowed down in people who eat a diet rich in antioxidant vitamins (carotenoids, vitamins C and E) or minerals (selenium and zinc). We identified 13 randomised controlled trials that included 6150 participants; five trials based in the USA, two in the UK, two trials in Austria, and one trial in each of a further four countries (Australia, China, Italy and Switzerland). The review of trials found that supplementation with antioxidants and zinc may be of modest benefit in people with AMD. This was mainly seen in one large trial that followed up participants for an average of six years. The other smaller trials with shorter follow‐up do not provide evidence of any benefit. Large well‐conducted trials in a range of populations and with different nutritional status are required. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed.

Vitamins for epilepsy

No evidence that folic acid, thiamine, vitamin D or vitamin E improve seizure control or prevent side effects for people with epilepsy.

Antioxidant vitamins and mineral supplements to prevent the development of age‐related macular degeneration

Age‐related macular degeneration (AMD) is a condition affecting the central area of the retina (back of the eye). The retina can deteriorate with age and some people get lesions that can lead to loss of central vision. Some studies have suggested that people who eat a diet rich in antioxidant vitamins (carotenoids, vitamins C and E) or minerals (selenium and zinc) may be less likely to get AMD. The authors identified four large, high‐quality randomised controlled trials which included 62,520 people. The trials were conducted in Australia, Finland and the USA and investigated the effects of vitamin E and beta‐carotene supplementation. These trials provide evidence that taking vitamin E and beta‐carotene supplements is unlikely to prevent the onset of AMD. There was no evidence for other antioxidant supplements and commonly marketed combinations. Although generally regarded as safe, vitamin supplements may have harmful effects and clear evidence of benefit is needed before they can be recommended.

See all (325)

More about Vitamin

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Other terms to know:
Micronutrient, Mineral, Nutrient

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