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Vitamin A: Essential nutrition guide

A is for Vitamin A. Dr Sarah Brewer and Rob Hobson take us through the A to Z of vitamins and minerals.

Vitamin A
Some older people not getting recommended daily intake of vitamin A.

What is Vitamin A?

Vitamin A is a collective term for a group of powerful antioxidants, known as retinoids, which are found in both animal and plant foods.

Who’s deficient?

According to the National Diet and Nutrition Survey 12% of men and 8% of women aged between 19 and 65 years do not get enough of the vitamin in their diet. Amongst those over 65 there are 10% of men and 7% of women who do not meet recommended daily intake in their diet.

Deficiency is sometimes diagnosed in people with absorption problems, chronic liver disease or alcohol dependency associated with a poor diet.

One of the first signs of vitamin A deficiency is a loss of sensitivity to green light, followed by difficulty in adapting to dim light (night blindness), hence the adage that ‘carrots help you see in the dark’. More severe deficiency can lead to:

  • Scaly skin with raised pimply hair follicles (keratosis pilaris)
  • Flaking scalp
  • Brittle, dull hair
  • Loss of appetite
  • Reduced male fertility
  • Impaired hearing, taste and smell
  • Dry, burning, itchy eyes (xerophthalmia)
  • Hardening of the cornea
  • Corneal ulceration
  • Visual loss, including blindness
  • Low resistance to infection

Why we need it? 

Vitamin A is needed to maintain normal growth and development, sexual health and fertility, healthy skin, teeth, bones and mucous membranes, healing of sores, wounds, and burns, and colour vision. Within the eye, vitamin A is converted into a pigment, rhodopsin, which is also known as visual purple. It is also important for immunity as it plays a key role In maintaining the body’s natural defences which include the mucus barriers in your lungs, eyes and gut which trap bacteria and other pathogens.

How does it work?

It binds to receptors within the nucleus of cells to regulate the way in which genes are activated. It is vital to produce numerous proteins, including enzymes, hormones and growth factors.

Assortment of vitamin A rich foods
An assortment of foods rich in vitamin A.

Where do we can get it from?

Foods from animals contain preformed vitamin A in a form your cells can use: 

  • animal and fish liver
  • meat
  • oily fish and cod liver oil
  • dairy products
  • eggs
  • milk and dairy products
  • butter (margarine is also fortified by law to contain as much vitamin A as in butter).

Plant based foods such as dark green leaves, fruit and vegetables contain carotenoid pigments of which some can be converted into vitamin A. However, it is easily destroyed by exposure to light and heat, however, so once you cook food by boiling or frying, its vitamin A content falls

How can I include it in my diet?

Start the day with an egg is a good way to make sure you are getting a good mount of vitamin A in your diet and you could serve this with smoked salmon for another good source. A simple stir fry made with beef and green vegetables such as broccoli, spring greens and orange peppers will also supply you with a large amount of vitamin A. Even a simple breakfast smoothie made with milk, yoghurt and orange fruits such as mango or canned peaches can offer another useful source of vitamin A.

Supplements

Vitamin A is included in multivitamin and mineral supplements, usually in the form of mixed carotenoids.

The EU nutrient reference value for vitamin A (retinol) is 800mcg per day.  The upper safe level for long-term intake from both diet and supplements is suggested as 1500mcg (5000 IU).

Do not exceed the recommended dose as excess can cause side effects such as headache, irritability, blurred vision, nausea, weakness, fatigue, abdominal pain and loss of appetite.

What to avoid? 

Taking high dose betacarotene supplements has been linked with an increased risk of lung cancer in smokers, and in those with previous occupational exposure to asbestos. Although this is controversial, it’s prudent for smokers to avoid taking betacarotene supplements, and obtain these compounds naturally by eating plenty of red-yellow-orange-green fruit and vegetables.

Not relevant most probably, but something to be aware of, pregnant women are advised to avoid foods that are high in vitamin A such as liver and to avoid supplements containing retinol vitamin A (except under medical supervision). Excess vitamin intake has been linked with some congenital defects. The safest way to obtain your recommended daily intake during pregnancy is in the form of natural carotenoids found in fruit and vegetables, which is converted into retinol when needed.

To find out further information about supplements or if you have any queries about taking supplements you can visit healthspan or speak to a  qualified nutritionists.

If you enjoyed this guide to vitamins, you’ll find more stories on our health channel by Sarah Brewer and Rob Hobson.

Tags: Last modified: September 14, 2021

Written by 11:12 am Nutrition