Vitamin A
Vitamin A is a fat-soluble vitamin needed for vision, immunity and cell renewal. It reaches us in different forms, from animal and plant sources alike.
| Type | Fat-soluble vitamin |
|---|---|
| Main roles |
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| Sources |
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| Deficiency note | Inadequate intake is associated over the long term with difficulty seeing in low light and a tendency to infection; a definite assessment calls for a health service. |
| Caution | Because it is fat-soluble it can accumulate in the body, and high-dose supplements are risky in pregnancy in particular. A supplement should be started only after a doctor's assessment. |
Two different forms: retinol and beta-carotene
Vitamin A enters the body by two routes. Animal sources (liver, egg yolk, dairy products) provide retinol, a form the body can use directly. Orange and dark green vegetables and fruit such as carrots, spinach and apricots provide beta-carotene, which the body converts into vitamin A as it needs it. Because of this two-way system, someone who eats a varied diet can usually meet their requirement from food.
What does it do in the body?
Vitamin A is most often associated with night vision: it takes part in making the pigments that let the eye see in low light. Beyond that it plays a role in how immune cells work, in the renewal of skin and mucous tissues, and in regulating cell growth. Daily requirements vary with age, sex and circumstances such as pregnancy; no single number holds for everyone.
What being fat-soluble means
Fat-soluble vitamins (A, D, E and K) can be stored in the body, which means that, unlike the water-soluble ones, any excess is not easily passed out in urine. With intake from food this generally causes no problem, but long-term use of high-dose supplements can lead to accumulation. High-dose vitamin A supplements carry a risk in pregnancy in particular. Whether a supplement is needed should be decided by a doctor on the basis of blood values and individual circumstances.
Related terms: Vitamin D, Vitamin E, Spinach