Vitamin A

Vitamin A is one of those nutrients many people recognise by name, but fewer understand in detail. It plays a quietly essential role in keeping the body working as it should, particularly when it comes to vision, immune health, and the condition of the skin and internal linings.

For most people in the UK, getting enough vitamin A is straightforward when eating a reasonably varied diet. At the same time, vitamin A is one of the few vitamins where too much can cause problems, which makes understanding safe intake especially important.

This guide explains what vitamin A does, how to get it from food, when supplements may be appropriate, and how to avoid excessive intake.

What vitamin A is and why it matters

Vitamin A is a fat-soluble vitamin, which means the body stores it in the liver and fatty tissues rather than excreting excess amounts straight away. This is useful because it means vitamin A does not need to be consumed every single day. However, it also explains why consistently high intakes can build up over time.

The term "vitamin A" refers to a group of related compounds that perform similar functions in the body. These include retinol, retinal and retinoic acid, which are active forms the body can use directly.

From a dietary point of view, vitamin A comes in two main forms:

Preformed vitamin A, found in animal foods and ready for the body to use
Provitamin A carotenoids, found in plant foods and converted by the body as needed

Beta-carotene is the most important provitamin A carotenoid and is responsible for the orange colour of foods like carrots and sweet potatoes.

Vitamin A supports everyday health in several key ways, particularly vision, immune function, and the maintenance of healthy skin and tissues.

Vision and eye health

Vitamin A is best known for its role in vision, especially in low-light conditions. The retina relies on vitamin A to produce rhodopsin, a pigment that allows the eye to respond to light. When vitamin A intake is too low, rhodopsin production is reduced, which can make it harder to see in dim environments.

People sometimes notice this as difficulty adjusting when moving from bright light into darkness, such as when entering a poorly lit room or driving at dusk. This is commonly referred to as night blindness.

Vitamin A also helps maintain the health of the cornea and the conjunctiva. These structures need to remain moist and intact to protect the eye from infection and damage. When vitamin A levels are very low for a prolonged period, the eyes can become dry and more vulnerable, although this is rare in the UK.

Immune function and barrier protection

Vitamin A plays a supportive role in the immune system, particularly by helping maintain the body’s physical barriers. The skin, the lining of the respiratory tract, and the lining of the gut all act as the first line of defence against infection. Vitamin A helps keep these surfaces healthy and resilient.

It also supports the normal function of certain immune cells. This does not mean vitamin A "boosts" the immune system in a dramatic way. Rather, it helps the immune system function as it should. There is no good evidence that taking vitamin A supplements prevents common infections in people who already have adequate intake.

Skin health and cell renewal

Vitamin A is involved in the growth, repair and turnover of cells throughout the body. This is particularly important for the skin and mucous membranes. Adequate vitamin A intake helps maintain smooth, resilient skin and supports normal wound healing.

When vitamin A intake is very low, the skin may become dry, rough or flaky, and internal linings may become less effective at retaining moisture. These changes happen gradually and are usually seen only in cases of significant deficiency.

Preformed vitamin A vs beta-carotene: why the difference matters

Understanding the difference between preformed vitamin A and beta-carotene is important for both nutrition and safety.

Preformed vitamin A, found in animal foods, is absorbed efficiently and can be used by the body straight away. Because it is already active, it can also accumulate in the liver if intake is consistently high.

Beta-carotene, found in plant foods, must be converted into vitamin A by the body. This conversion is regulated according to need. If vitamin A stores are sufficient, the body converts less beta-carotene.

The practical implications are:

Preformed vitamin A can build up and cause toxicity if intake is too high
Beta-carotene does not cause vitamin A toxicity
Eating large amounts of colourful vegetables is safe

Very high beta-carotene intake can cause a harmless yellowing of the skin, which resolves when intake is reduced.

How common is vitamin A deficiency in the UK?

True vitamin A deficiency is rare in the UK. Most people obtain enough through a varied diet, and clinical deficiency is usually linked to underlying medical conditions rather than poor food choices.

UK hospital data show that symptomatic deficiency occurs infrequently and is most often seen in people with conditions that affect fat absorption or nutrient metabolism.

That said, some groups are at higher risk and may need closer monitoring.

People more likely to be affected include those with long-term digestive conditions, individuals with chronic alcohol misuse, and people who have undergone certain types of weight-loss surgery. Strict vegan diets can also increase risk if they lack sufficient beta-carotene-rich foods, although this is uncommon in practice.

Signs vitamin A intake may be low

Early signs of low vitamin A intake are often subtle and non-specific. Experiencing these symptoms does not confirm deficiency, but they may warrant further assessment.

Possible signs include:

Difficulty seeing in dim light
Dry or irritated eyes
Dry, rough or flaky skin

Because these symptoms can have many causes, anyone experiencing persistent issues should seek medical advice rather than self-diagnosing or starting supplements without guidance.

Getting vitamin A from food

For most people, food is the safest and most effective way to meet vitamin A needs.

Animal foods provide preformed vitamin A, while plant foods provide beta-carotene. A diet that includes both generally supplies adequate amounts without risk.

Liver is by far the richest source of vitamin A. However, because it contains extremely high levels, it should be eaten no more than once a week and avoided altogether during pregnancy.

Other useful sources include dairy products, eggs, oily fish and fortified spreads. Plant sources such as carrots, sweet potatoes, squash, spinach and kale provide beta-carotene, which the body converts safely as needed.

Because beta-carotene is fat-soluble, absorption improves when these foods are eaten with a small amount of fat.

When vitamin A supplements may be appropriate

Most adults in the UK do not need vitamin A supplements. There are, however, specific situations where supplementation may be recommended.

These include:

Children aged six months to five years, who are advised to take vitamin drops containing vitamins A, C and D
People with medically diagnosed deficiency due to malabsorption
Individuals under specialist care where intake is known to be inadequate

Standard multivitamins usually contain moderate amounts of vitamin A. However, it is important to consider total intake from all sources, including liver, fortified foods and fish liver oil supplements.

Pharmacist comment

"Vitamin A is essential, but it’s also one of the vitamins where more is not better. In pharmacy, we focus on a food-first approach and caution with supplements, particularly for pregnant women and older adults. Most people don’t need extra vitamin A, and it’s important to check labels to avoid unintentionally taking too much from multiple products." - Alessandro Grenci, Superintendent Pharmacist

Can you take too much vitamin A?

Yes. Unlike water-soluble vitamins, vitamin A is stored in the body. Consistently high intakes of preformed vitamin A can lead to toxicity over time.

UK guidance suggests keeping long-term intake below 1,500 micrograms per day from all sources combined. Higher intakes may increase the risk of bone thinning and fractures, particularly in older adults.

Symptoms of excessive intake can include headaches, dry or peeling skin, hair loss, bone pain and fatigue. Severe toxicity is rare but can cause liver damage.

These risks do not apply to beta-carotene from plant foods.

Pregnancy and vitamin A: special precautions

Vitamin A is essential for fetal development, but excessive intake of preformed vitamin A during early pregnancy can cause serious harm.

For this reason, UK guidance is clear. Pregnant women and those trying to conceive should:

Avoid supplements containing vitamin A or fish liver oil
Avoid liver and liver products such as pâté
Use pregnancy-specific multivitamins that exclude retinol

Beta-carotene from fruit and vegetables is safe during pregnancy.

Who should be particularly cautious

Some people need to take extra care with vitamin A intake:

Pregnant women or those planning pregnancy
People who eat liver regularly
Older adults at risk of osteoporosis
Anyone taking multiple supplements

Checking labels and seeking advice from a pharmacist can help prevent accidental over-consumption.

When to speak to a healthcare professional

You should seek advice if you have a medical condition affecting digestion or absorption, if you are pregnant or planning pregnancy, or if you are considering supplements alongside an already varied diet.

Persistent symptoms such as night vision problems, eye dryness or unexplained skin changes should always be assessed by a healthcare professional.

Pharmacists can help review supplement use, identify duplication, and advise on safer alternatives where appropriate.

Final thoughts

Vitamin A is essential for vision, immune health and the maintenance of healthy skin and tissues. For most people in the UK, a varied diet provides all that is needed, and supplements are unnecessary.

The key is balance. Beta-carotene-rich plant foods are safe and beneficial, while preformed vitamin A requires caution, particularly from liver and supplements.

A food-first approach, combined with awareness of high-risk situations, is the safest and most effective way to support vitamin A intake for long-term health.

Sources

Written by Christian Jakobsson