Everything you need to know about vitamin A
Vitamin A is the collective term for a group of fat-soluble retinoids which are essential for many processes in the body
What is vitamin A?
Vitamin A is the collective term for a group of fat-soluble retinoids which are essential for many processes in the body. Several genes involved in immune responses are regulated by Vitamin A. Vitamin A also helps maintain the integrity of all surface tissues including the skin, the lining of the respiratory tract, the bladder, the gut and the eyes. Vitamin A is an important part of the rhodopsin molecule, activated when light shines on the retina. The retina then sends a signal to the brain which gives us our sense of vision. Healthy levels of vitamin A in the body play a role in the prevention of macular degeneration, the leading cause of age-related blindness. The antioxidant properties of vitamin A help to fight inflammation through neutralising free radicals that can lead to tissue damage.
How do we get vitamin A?
There are 2 main forms of vitamin A, active vitamin A and beta-carotene. Active vitamin A or ‘retinol’ comes from animal-derived foods and can be used directly by the body. In contrast, the other form of vitamin A, ‘provitamin A’ is obtained from fruits and vegetables in the form of carotenoids, which the body converts to retinol after food is eaten.
Cheese, eggs, lamb and beef liver, as well as oily fish such as mackerel, salmon and trout, are all great sources of active vitamin A. Coloured fruit and vegetables including spinach, carrots, sweet potatoes, mango, papaya and apricots are all good sources of beta-carotene. The NHS recommends that for adults, (19-64 years) 0.7 mg of vitamin A should be consumed per day for men and 0.6 mg of vitamin A a day for women.
What are the symptoms of vitamin A deficiency?
Vitamin A deficiency is uncommon in Western countries but common in developing countries. Night blindness is one of the earliest signs of a vitamin A deficiency which can potentially lead to permanent blindness if left untreated. Vitamin A deficiency can also cause respiratory infections, weight loss, dry skin and hair. People who suffer from illnesses that affect the way food is absorbed from the gut including coeliac disease, Crohn's disease and cystic fibrosis are at a greater risk of developing vitamin A deficiency. Treatment of vitamin A deficiency often includes increasing consumption of vitamin A-rich foods and taking daily oral vitamin A supplements.
For those who are pregnant, having large amounts of vitamin A can harm the unborn baby. If you are pregnant or thinking about having a baby, it is recommended that you don't eat liver or liver products, because these are very high in vitamin A. Avoid taking supplements that contain vitamin A and speak with your GP or midwife for further advice.