Vitamin A

What Is Vitamin A?

Vitamin A is a fat-soluble vitamin which is stored in the body. It is an essential micronutrient, meaning our body is unable to make it so we must get it from our diet. We get vitamin A from the foods that we eat and it is stored in the liver until it is needed.[1]

Which tests include this marker?

What Role/s Does It Play in The Body?

Many physiological processes in the body require vitamin A, including:

  • Maintenance of the function and integrity of surface tissues – skin, the lining of the respiratory tract, gut and the eye
  • Replacement of dead skin cells daily
  • Helping with vision in poor conditions
  • Maintaining the good health status of the immune system
  • Growth and development
  • Reproduction

There are 2 main sources of vitamin A: plant and animal sources. In animal sources, vitamin A is found in its active form, retinol. Whereas, in plant sources, vitamin A is in the form of carotenoids which need to be converted into retinol when digested before the body can use it. Carotenoids give plants their green colour and fruit their red or orange colour.

Too much vitamin A can be toxic, while a deficiency can have several health implications.

How Does Vitamin A Affect My Wellbeing?

Vitamin A deficiency is rare in the United Kingdom and is often a result of malnutrition, but it is a problem in developing countries where there is a limited diet available. Changes in vision are the first signs of vitamin A deficiency. You may find it is more difficult to see in poor light or at night. Other symptoms include:

  • Dry, irritated eyes
  • Dry hair, skin, mouth
  • Loss of tears
  • Fatigue
  • Diarrhoea
  • Bladder infections
  • Vaginal infections
  • Respiratory infections
  • Poor wound healing[2]

These symptoms are mainly associated with the linings in the body. Vitamin A is important in the maintenance of surface tissues such as the skin and linings of organs. Therefore, if you are deficient the symptoms are likely to affect these areas. 

Vitamin A toxicity usually occurs when too much of the micronutrient is ingested, particularly with the use of supplements.[3] Symptoms may include:

  • Blurred vision
  • Nausea
  • Bone pain
  • Reduced appetite
  • Dizziness
  • Swelling

How Can I Improve My Result?

You can ensure you get a good intake of vitamin A by including rich sources in your diet. If you acquire enough in your diet there should be no need for additional supplementation. If you are pregnant you should speak to your GP about the safe levels of vitamin A during pregnancy. High retinol levels can be an issue so you should restrict your intake from foods such as liver and eggs.


There two sources of vitamin A: plant and animal.
Plant sources

  • Carrots
  • Cantaloupe melon
  • Tomatoes
  • Mango
  • Sweet potato
  • Red peppers
  • Peas
  • Spinach

Animal sources

  • Liver
  • Egg yolk
  • Milk
  • Fish

It is important when preparing these foods that they are not overcooked as this can decrease their vitamin A content. 


Exercise has a beneficial impact on the gut environment and the diversity of the microbes which live in it.[4] Therefore, exercise is an important aspect of a healthy lifestyle and could aid with the normal functions within the body.  

Everyone should aim for at least 150 minutes of aerobic exercise per week, carried out over a period of 5 days. Activities can include walking, jogging, swimming and cycling.

Tests that include this marker


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[1] Gilbert, C. (2013). What is Vitamin A and Why Do We Need It? Community Eye Health Journal: 26(84), p65.

[2] North London Obesity Surgery Service. (2018). About Vitamin A and Vitamin A Deficiency. Available at:

[3] Lab Tests Online UK. (2017). Vitamin A. Available at:

[4] Clarke, S, F., Murphy, E, F and O’Sullivan, O et al. (2014). Exercise and Associated Dietary Extremes Impact on Gut Microbial Diversity. Gut: 63, pp 1913-1920.

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