Vitamin A


What is vitamin A?

Vitamin A is a generic term for ‘retinoids’. Retinoids are a group of structurally related chemical compounds, that possess the biological activity of retinol. Retinol is a yellow compound that is essential for growth and for vision in dim lighting. Therefore, it is necessary for normal functioning – eye health, growth and development and immune status. It is a fat-soluble vitamin so it is stored in the liver (Around 90%).




What are the sources?

Animal – liver, dairy products, eggs (yolk), cod liver oil
Plant – Orange and yellow fruit and vegetables (Carrots, sweet potato etc), dark green leafy veg




Bioavailability

Animal sources are 70-90% bioavailable, but to get the best absorption you should take it with fat. However, cooking these for too long can affect the level of vitamin a that is absorbed. Iron also is really important because if there is no iron in the body then you won’t be able to access the stores from the liver. 
This is a similar case for zinc, because it releases an enzyme that helps to distribute the Vitamin A.

Vitamin A Deficiency

Can occur when the bodies reserves are depleted to a limit which affects physiological processes. It can mainly affect children and women of reproductive again. According to the World Health Organisation, it is the leading cause of preventable blindness in children, and can also increase the risk of disease and death from severe infections – respiratory disease, measles, diarrhoea etc. 
In pregnant women, this can cause night blindness and can also increase the risk of maternal mortality because of the lack of immune function.
However, even in some of the more advanced stages, some people may react well with vitamin A treatment and this can prevent permanent blindness. There can be a response within 2-5 days of therapy and normal vision can resume after 1-2 weeks. 
Vitamin A deficiency influences a severe infection, as it is classed as an ‘anti-infective’ vitamin.




What is the scale of the problem around the world?

This is a massive public health problem in 50% of all countries including Africa and South East Asia. It is estimated that 250 million preschool children are vitamin A deficient with 250,000-500,000 vitamin A deficient children becoming blind. And because blindness is one of the last symptoms to show, 50% of these children die within 12 months because of the low immune system.
The prevalence for vitamin A deficiency is among low income communities because they have a diet mainly focused on rice or other carbohydrates. They are high in calories but very low in micronutrients.


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