What is vitamin A?
Vitamin A is a fat-soluble compound with the same biological effect as retinol. “Fat soluble” means it is stored in the body’s adipose (or fat) tissues and liver when your body isn’t using it. This is why you should not exceed the recommended daily intake of vitamin A.
Your body releases the vitamin when it needs it and about 90% is stored in the liver. Supplies of vitamin A usually last up to a year in healthy people.
Vitamin A is important for normal vision, reproduction, growth and immune function, as well as the maintenance of normal mucous membranes.
What are food sources of vitamin A?
We usually get enough vitamin A through a normal, healthy diet but there are some foods that contain more vitamin A than others, for example:
- Liver and liver pâté
- Cod liver oil
- Oily fish such as mackerel, salmon, trout, herring
- Eggs
- Whole milk, butter, cream, cheese
- Broccoli, brussel sprouts
- Spinach, kale, lettuce
- Red pepper
- Apricots, melon, grapefruit
- Sweet potatoes, pumpkin, carrots
- Squash
These fruits and vegetables contain carotene, which is converted into retinol in the body when needed. In food, retinol and carotene are the most important forms of vitamin A, where retinol is found in animal foods and carotene in vegetables.
Carotenoids are a group of over 600 substances in plants and some of these can be converted into vitamin A in the body, with beta-carotene being the most important. Preferably, the body should produce vitamin A by itself and in order to do so, it’s important to eat enough foods containing beta-carotene.
Cod liver oil is a good source of vitamin A, and a spoonful of cod liver oil every day is important for all age groups.
What are the other health benefits of vitamin A?
Besides playing a role in cell specialisation (whereby new cells are modified so they can perform their function efficiently), Vitamin A helps to maintain normal
- iron metabolism
- mucous membranes
- skin
- function of the immune system
- vision
Vitamin A is known as ‘the vitamin of the eye’ due to its importance to specific cells in the retina and their ability to detect light. Vitamin A is therefore especially important for good night vision.
Too much or too little vitamin A
As with everything in life, it’s all about the balance when it comes to vitamin A. It’s not good to have an excess or deficiency of vitamin A, but the body usually manages to produce enough vitamin A when it needs it.
If you take in too much vitamin A over a long time, you could experience poisoning symptoms. A golden rule is to not take more than one dietary supplement containing vitamin A. If you are taking cod liver oil and want a supplement of other vitamins as well, opt for a multi-vitamin supplement without vitamins A and D.
Vitamin A deficiency is uncommon in the First World but in developing countries it’s still one of the most common causes of blindness. The earliest symptoms of vitamin A deficiency are decreased ability to adapt to light and loss of night vision. Wounds on the skin that don’t heal can also be an early symptom of vitamin A deficiency. As vitamin A is essential for the immune system, children with a mild deficiency are at a higher risk of infections.