What is vitamin A and why do we need it? The understanding nutrients series
We’re back with another nutrient! This time we’re doing vitamin A. You can find all the other nutrients I’ve covered here.
You’re probably familiar with vitamin A helping you see in the dark. But there’s a lot more to this vitamin than that.
Roles of vitamin A:
Vitamin A plays lots of roles in the body, but I’ll just touch
on a few here.
Vision: there’s a common myth that eating carrots can help you
see in the dark. This is because carrots are a good source of vitamin A. Vitamin
A plays a crucial role in eyesight. It helps form rhodopsin, which is a protein
in your retina that’s sensitive to light. Light entering the retina is what allows
us to see. Vitamin A also helps the formation of other parts of the eye, like
the cornea.
Growth and development: vitamin A plays a key role in cell
development and differentiation. Cell differentiation is the process in which
cells become specialised and take on a particular role. For example, a cell may
become a skin cell or an immune system cell. Vitamin A plays a key role in
this, so you could say it helps each cell do its job.
Immune system: a key place that vitamin A helps cell development
is in the immune system. It helps all the different immune cells mature
properly to carry out their role. This helps the body defend itself against
infection.
Skin: vitamin A also plays a part in our skin and membranes.
It helps form the epithelium, which is the inner and outer lining of our
bodies. Maintaining this lining helps protect us from disease. Without vitamin
A your skin would become dry, and the lining of your inner organs would harden.
How much vitamin A should we be having?
An adult man should have 700 μg of vitamin A daily. An adult
woman should have 600 μg daily, with an additional 100 μg if pregnant.
For references, 2 large eggs contain 120 μg of vitamin A.
And it doesn’t matter if we get our vitamin A from animal
products or plant products.
Foods that are high in vitamin A:
This isn’t a complete list, but here are a few examples of
food high in vitamin A. Dairy products, liver, yellow fruits, and brightly
coloured vegetables are all good sources of vitamin A.
- 100g of liver has 7300μg
- 100g of carrots has 1960μg
- 100g of sweet potato has 855μg
- 100g of spinach has 589μg
- 100g of cheddar cheese has 388μg
- 100g of tuna has 80μg
It’s worth noting that liver and liver products like pate
are extremely high in vitamin A. And as vitamin A is a fat soluble vitamin, it’s
stored in the body, in the liver. To reduce the risk of a possible vitamin A build
up, liver shouldn’t be eaten more than once a week. If you’re pregnant, liver
should be avoided entirely. It can become toxic if consumed in excess.
What happens if you don’t get enough vitamin A?
A deficiency in vitamin A is rare. But it can be caused by a
poor diet, poor absorption, or an issue with the liver.
It can lead to xerophthalmia which is an eye disease that
begins with poor vision and night blindness. It can eventually lead to total
blindness if untreated. Other symptoms include frequent infections, dry skin,
and skin irritation.
Vitamin A deficiency is treated with high dose
supplementation. This is through tablets or injections.
Key points:
- Vitamin A has many roles in the body including our eye health, supporting our immune system, and helping our skin.
- Adult men need 700 μg of vitamin A daily, and adult women need 600 μg daily.
- Foods like liver, eggs, dairy products, and some fruit and veg are good sources of vitamin A.
- Vitamin A is fat soluble and can build up in the body if eaten in excess.
- A deficiency in vitamin A is rare but can lead to xeropthalmia (an eye disease), and dry skin.
I hope you enjoyed this blog post;
I’d love to hear your thoughts in the comments below!
Bye for now! 👋
References:
https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-a/
https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
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