Vitamin A

Vitamin A

Vitamin A is a vital fat-soluble vitamin that can greatly improve your overall health. It is derived from two different sources: pre-formed retinoids and pro-vitamin carotenoids. As a supplement, Vitamin A has many health benefits.

Vitamin A is great for maintaining eye health. It is also great for skin, bones, immune system and to improve fertility. Beta-carotene and other carotenoids are antioxidants that can help decrease your risk of cancer.

The Different Forms of Vitamin A

As mentioned above, Vitamin A is a vital fat-soluble vitamin. Vitamin A itself comes in many forms, but the three most significant forms are retinol, retinal, and retinoic acid.

Despite being very similar in name, the three forms each play different roles in the body, which we will discuss in more detail below:


Retinol, the animal form of Vitamin A, is the most common supplement form. Retinol is also the “food form” of Vitamin A, and the body can easily convert it to retinal and retinoic acid as needed.

Food sources of retinol, the active form of Vitamin A, include animal products like eggs, liver, beef and dairy products. Beta-carotene and the other carotenoids, which can be converted to Vitamin A in the body, are found in orange fruits and vegetables. This is why it’s called Retinol as it helps keep the retina in the eye healthy.


Retinol can be converted in the body to Retinal. Retinal is the form of Vitamin A that plays a vital role in eye health. It regulates the conversion of light into impulses that allow us to see. Because of this important function of retinal, Vitamin A deficiency is often characterized by vision impairment and night blindness.

Retinoic acid

Retinol can also be converted in the body to Retinoic acid, which is important for healthy skin, bones and teeth. It can prevent keratinization, or the drying out and hardening of skin [1]. For this reason, Vitamin A is commonly used as a treatment in disorders of skin keratinization.

Other Health benefits of Vitamin A

Vitamin A is also very important in the body for; immune support, reproductive health, menstrual regulation in women, cellular growth and metabolism.


Beta-carotene is the precursor of Vitamin A. It is a pigment that is highly concentrated in orange vegetables such as carrots and sweet potatoes. Beta-carotene possesses antioxidant properties, meaning that it can be used to destroy harmful free radical molecules that cause cellular damage. This is called oxidative stress, and this is why coloured fruit and vegetables reduce oxidative stress, and why the advise is to ‘eat a rainbow of different foods’.

Beta-carotene and other antioxidants are being studied for their applications in cancer prevention. They are also great at helping to prevent disease.

The good thing about getting Vitamin A from Beta-carotene, rather than from animal sources such as Liver, is that the body only converts it to Vitamin A as needed, so overdose is not a risk, unlike with consuming Liver where it is a very well known risk, as we will discuss below.

Vitamin A Overdose in the Arctic

Concerns around vitamin A toxicity from eating a dog’s liver in the Arctic, is rooted in historical incidents. In the early 20th century, during Arctic explorations, there were instances where explorers or indigenous people developed symptoms of vitamin A toxicity after consuming the livers of polar bears or sled dogs, when no other food sources were available. The symptoms include; nausea, dizziness, blurred vision, and, in severe cases, can lead to more serious health issues.

Vitamin A toxicity is known as “hypervitaminosis A” or “polar bear liver disease.” It has been associated with the consumption of the livers of certain Arctic animals, including polar bears and sled dogs.

The livers of these animals contain extremely high levels of vitamin A, particularly in the form of retinol, which can be toxic in excessive amounts. The toxicity is a result of bioaccumulation, where animals at the top of the Arctic food chain, such as polar bears, accumulate large amounts of vitamin A from consuming prey like seals.

It’s essential to note that the average diet and food sources in most regions do not pose a risk of vitamin A toxicity. Animal livers, in general, are rich in vitamin A, but consumption as part of a balanced diet typically does not result in harmful levels. However, in specific Arctic contexts where the liver of certain animals is a significant dietary component, there is a risk of vitamin A toxicity.

In modern times, awareness of this issue has led to precautions and dietary guidelines, and the consumption of certain animal livers is approached with caution in the Arctic regions. It’s a reminder of how environmental factors and dietary practices can have unique health implications in different parts of the world.

Vitamin A WWII Radar Myth

The association between radar, retinol and carrots during World War II is a part of historical misinformation that has persisted over the years. The story is a combination of facts and myths.

Here are the key facts:

Radar: During World War II, radar technology played a crucial role in air defense. The British Royal Air Force (RAF) had developed an effective radar system for detecting incoming enemy aircraft. To maintain the secrecy of this technology, the British government spread the misinformation that their pilots had superior night vision due to eating carrots, suggesting that carrots improved eyesight and, therefore, the ability to see in the dark.

Carrots and Vitamin A (Retinol): Carrots are a good source of beta-carotene, which the body can convert into vitamin A, also known as retinol. Vitamin A is essential for maintaining healthy vision, skin, and other tissues. However, consuming excessive amounts of carrots or beta-carotene does not enhance vision beyond the body’s natural requirements.

Myth and Misinformation: The British government’s attempt to keep radar technology a secret led to the dissemination of the myth that eating carrots could give pilots superior night vision. This was a deliberate misinformation campaign to conceal the existence and effectiveness of radar.

In reality, while vitamin A is crucial for maintaining healthy eyes and vision, consuming excessive amounts of carrots or vitamin A-rich foods does not result in superhuman night vision. The idea was more about diverting attention and creating a plausible cover story than promoting actual health benefits.

The association between carrots, radar and improved vision during World War II is an interesting example of wartime propaganda and how myths can persist even after the truth is revealed.

Vitamin A Deficiency

Vitamin A deficiency is characterised by; stunted growth, impaired vision, night blindness and increased susceptibility to disease. In extreme cases, complete blindness can occur. Too little Vitamin A can cause Bitot’s Spots and then keratinisation of the eyes.

This is a common problem amongst children in Asia, due to poor diet. Deficiency also contributes to increased mortality and impaired lactation among children, pregnant women and new mothers.

Vitamin A Supplements

Vitamin A supplements can come in a variety of forms. Most supplements are synthetic or animal-based retinol. However, you can purchase carotenoid supplements too.

Because Vitamin A is a fat-soluble vitamin, it needs to be taken with a small amount of fat to be properly absorbed and utilized by the body. Vitamin A supplements should be purchased as gel caps or drops that contain an oil. The most commonly-used oils in vitamin supplements are soybean and sunflower oil, so try to purchase a Vitamin A supplement that is oil-based for maximum effectiveness.

Vitamin A Dosage and RDA

The recommended amount of retinol needed to prevent Vitamin A deficiency is 900 micrograms for men and 700 micrograms for women. Many supplement manufacturers report Vitamin A amounts in International Units (IU). Men should aim for 3,000 IU per day, and women should aim for 2,333 IU per day of Vitamin A in any of its forms [2]. However, do not exceed 10,000 IU of Vitamin A per day.

See also our section on Vitamins.

Always take care when taking herbs and Read Our Disclaimer.

Vitamin A Notes / Side Effects

There are some important things you should know before you take a Vitamin A supplement. The Tolerable Upper Limit of Vitamin A is 10,000 IU. This means that you should take no more than 10,000 IU per day. When you consume more than the Tolerable Upper Limit of any nutrient, harmful side effects may occur [3]. It is not advised to take Vitamin A supplements, or eat liver when pregnant, as too much vitamin A causes toxicity.



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