What is Vitamin A?

Vitamin A is the name of a group of fat-soluble retinoids, including retinol, retinal, and retinyl esters. It comes in two forms:

• retinol (also known as preformed vitamin A) which is found in foods from animal sources, such as dairy products, fish, and meat (especially liver), and
• Beta-carotene which is found in plants. It is by far the most important carotenoid found in plants.

Beta-carotene is sometimes called a pro-vitamin because it must be broken down by the body into vitamin A before it can act as a vitamin. Several other carotenoids are found in food, such as lycopene, lutein, and zeaxanthin, but these are not converted into vitamin A.

Health Benefits of Vitamin A

The health benefits of vitamin A include:

1. Boosts the Immune System

Vitamin A strengthens the immune system as it is involved in the formation of B- and T-cells which are vital for the immune response. It therefore protects the body against infection.

2. Helps to maintain Eye Health

Vitamin A is essential for eye health and it helps to prevent certain eye conditions, such as age-related macular degeneration. This is the main cause of age related blindness in the elderly. Vitamin A helps to maintain good vision and is especially important for night vision and vision in dim light.

3. Helps Prevent Chronic Diseases

Vitamin A is a powerful antioxidant which neutralises harmful free radicals. Free radicals can cause oxidative stress which may lead to chronic diseases such as heart disease, diabetes, cancer and dementia.

4. Important for Fertility and Foetal Development

Vitamin A is essential for both male and female reproduction as it plays a role in sperm and egg development. It is also important for placental health and foetal development.

5. Healthy Skin

Beta-carotene is a powerful antioxidant which is important for glowing skin as it helps prevent the degeneration of cells, slows aging and makes the skin glow. Studies have shown that people who eat a high amount of carotenoid-containing fruits and vegetables, such as carrots, have more yellow tones in their skin giving them a complexion that others rate as looking healthier. In addition, vitamin A also helps to keep body tissues, eyes, bones and teeth healthy.

6. May Protect Against Certain Cancers

Due to their antioxidant properties, carotenoid-rich fruits and vegetables may protect against certain types of cancer such as bladder, breast and ovarian cancer.

Dietary Sources of Vitamin A

Vitamin A is found in a wide variety of foods. Retinol is absorbed and used by the body much more easily than plant-based sources of carotenoids. The body’s ability to convert carotenoids, such as beta-carotene, into active vitamin A depends on many factors, including genetics, diet, overall health and medications. It is therefore very important for vegetarians to ensure that they are getting enough carotenoid-rich foods.

Foods high in retinol (preformed vitamin A) include:

• Egg yolks
• Beef and chicken liver
• Liver sausage
• Dairy products such as whole milk, butter and cheese
• Fish oils such as cod liver oil
• Fish such as salmon, trout and mackerel

Foods high in pro-vitamin A carotenoids such as beta-carotene include:

• Green leafy vegetables such as kale, spinach, broccoli, collard greens, parsley, turnip greens,
• Sweet potatoes, carrots and cabbage
• Pumpkin and red peppers
• Butternut squash
• Yellow fruits such as apricots, mango and papaya

Signs of Vitamin A Deficiency

The health benefits of vitamin A are many. Signs of vitamin A deficiency include night blindness, slow or stunted growth in children, dry skin and eyes and increased susceptibility to infections. Vitamin A deficiency is in fact the leading cause of preventable blindness in children worldwide.

How much vitamin A do I need?

Vitamin A used to be labelled in IUs (International Units) but is now expressed in retinol equivalents (RE) to better distinguish between the two forms of vitamin A. The total vitamin A content of a food can also be expressed as micrograms (µg) of retinol equivalents (RE).

Adults aged 19 to 64 require:

• Men: 700 µg a day
• Women: 600 µg a day

Sufficient vitamin A is usually obtained from the diet. As it is fat soluble it can be stored in your body until your body needs; it is therefore not required every day.

Beta-carotene is preferred over vitamin A, and it is recommended that you buy a high-quality supplement that contains beta-carotene. Some supplements state “Vitamin A (as beta-carotene).”

Possible Side Effects of Vitamin A

Vitamin A is fat soluble and is stored in the body. Over time, if consumed excessively, it can reach toxic levels. Toxicity is most commonly associated with excessive supplement intake or treatment with certain medications, such as isotretinoin.  It is important not to exceed 10,000 IU (3,000 mcg) for adults to prevent toxicity.

Possible Interactions of Vitamin A

Taking vitamin A supplements while using medicines derived from vitamin A (such as isotretinoin) can lead to toxic side effects.

Precautions with Vitamin A

If you are pregnant, consuming large amounts of vitamin A can harm your unborn baby. So if you are pregnant or thinking about becoming pregnant, do not eat liver or liver products (such as pâté), as these are very high in vitamin A. In addition, avoid taking supplements which contain vitamin A.

Speak to your doctor or pharmacist if you would like more information.

Vitamin A supplements can be found here.