Vitamin A is one of the most important vitamins for the good functioning of the body. What exactly are the actions of vitamin A in our body and in which cases do we need supplements?
What is vitamin A?
Vitamin A is a fat-soluble molecule that is stored in the liver. In nature, there are two types of vitamin, a vitamin precursor molecule named retinol, which is found in meat, fish, poultry and dairy products, and provitamin A, which is mainly found in plant foods (fruits and vegetables). There are various provitamin A molecules, which are commonly known as carotenoids. There have been identified over 500 carotenoids that can be converted to vitamin A, but the most common among them is beta-carotene.
Vitamin A deficiency
Even though in the developed world, vitamin A deficiency is relatively rare, it will be wise to know and to identify the symptoms of deficiency.
- Dryness in the eyes
- Impaired dark adaptation (diminished vision in the dark or night)
- Skin diseases
Actions and properties
Vitamin A has many different actions in the body:
- It participates in the health of teeth and bones
- It is involved in maintaining the integrity of skin and cell membrane
- It participates in the production of pigments in the eyes and in night vision
- It contributes to reproductive capacity
- It offers antioxidant properties and preserves other molecules from oxidation
- It has anti-cancer properties (β-carotene)
Acne, psoriasis and skin diseases
Deficiency of vitamin A can lead to hyperkeratosis, dry and rough skin. Retinoids are synthetic molecules of vitamin A, which are used to treat severe acne and psoriasis. They are also widely used in cosmetics for their anti-aging properties and reduction of fine lines and wrinkles.
Deficiency of vitamin A leads to dry eyes and vision problems, especially during the night. Many studies have shown that individuals who receive adequate amounts of vitamin A are less likely to develop macular degeneration, cataracts.
Inflammatory Bowel Diseases (IBD)
People suffering from inflammatory bowel diseases, such as ulcerative colitis or Crohn’s disease, have a difficulty in absorbing nutrients, including vitamin A. Therefore, it is recommended to take a multivitamin supplement.
There are several studies which indicate that vitamin A exerts anti-cancer properties. Individuals who receive adequate amounts of beta-carotene through diet are less likely to develop breast, colon, esophageal and uterine cancer. On the contrary, taking high dosages of vitamin A or b-carotene from supplements may increase the likelihood of certain types of cancer.
Side effects and interactions
Vitamin A, as a fat-soluble molecule, thus can be stored in the body and especially in the liver. Taking large doses of vitamin A through diet or supplements is toxic. For this reason, vitamin A supplements should be taken under the supervision of a physician or dietician.
B-carotene is not stored in the body and so there is no such a big issue of toxicity. However, taking large doses may make the skin more yellowish-orange, which returns to normal once stop taking beta-carotene supplements. People with diabetes or liver disease should not take vitamin A without the doctor’s approval. In addition, alcoholics and people who smoke should not take supplements with β-carotene.
Both vitamin A and β-carotene may increase serum triglyceride levels. Taking any vitamin A or carotenoid supplement, it is not approved during pregnancy.
Available forms and supplements
It is marketed in supplements in both tablet and capsule form, either in the form of retinol or retinyl palmitate.
Recommended dosage and administration
Vitamin A is a fat-soluble molecule, thus it is advisable to consume it along with fat. The maximum daily dosage is 10,000 IU per day for adults. The recommended daily intake for men and women is 900 mcg and 700 mcg, respectively.
In Vita4you you can find a great variety of dietary supplements with vitamin A.