Our body needs a constant source of vitamins and minerals every day, yet we know little of what these vitamins can do to our health. Not many of us are familiar with Vitamin A. Vitamin A is actually a group of nutritional organic compounds composed of the substances retinoic acid, retinol and other carotenoids such as beta-carotene. This vitamin is important in the human body because it can boost growth and development of our organs and tissues, maintain our immune system, and promote good vision. The eye needs a constant supply of Vitamin A to form retinal in the retina, which further combines with the protein opsin to form rhodopsin, a light-absorbing molecule. Rhodopsin is responsible for both low-light vision and color vision. A type of Vitamin A, retinoic acid, functions as a growth factor for epithelial cells and other tissues.
The food that we eat can give a constant supply of Vitamin A to us. Vitamin A in food is available as retinol and carotenes such as alpha-carotene, beta-carotene, and gamma-carotene. Retinol is present in animal-derived foods while carotenes along with the xanthophyll beta-cryptoxanthin are found in certain plants, herbivores and omnivore animals. These vitamins are available in foods such as cod liver oil, beef liver, pork liver, fish, chicken liver, dandelion greens, sweet potatoes, broccoli, carrots, spinach, kale, butter, pumpkin, collard greens, cheddar cheese, melons, eggs, apricots, mango, papaya, milk, peas, tomatoes and seaweed.
We need to eat Vitamin A rich foods to enjoy its various benefits. Vitamin A is involved in the process of vision, gene transcription, immune function, embryonic reproduction and development, hematopoiesis, bone metabolism, skin health, cellular health and antioxidant activity. Vitamin A is said to help in the differentiation and maturation of skin cells. Retinoic acid or isotretinoin is said to reduce the secretions and size of the sebaceous gland to prevent pimples and breakouts from forming. If Vitamin A is deficient in the body, as in the case of children and adults who do not consume foods rich in vitamin A and in babies who were weaned early from breast milk, certain symptoms and illnesses may develop such as impaired vision, night blindness, xeropthalmia or blindness, impaired immunity, increased incidence of urinary tract infections and ear infections, meningococcemia, hyperkeratosis or white patches on hair follicles, and skin problems. Vitamin A is especially needed by pregnant women for normal fetal development of their babies. A deficiency of Vitamin A can lead to birth defects. Other states which can lead to deficiency of Vitamin A in the body include fat malabsorption, liver and gallbladder problems, cigarette smoking, and chronic alcoholism. Vitamin A may also be deficient in zinc deficiency, since zinc is essential for vitamin A absorption on the digestive tract.
Vitamin A in Autoimmune Disease and Transplant Recipients
Recent news has it that the form of vitamin A used by teenagers to prevent pimple formation can also be used to modify immune function in people with autoimmune disorders and those who have received organ transplants. The researchers from Penn State University Hershey College of Medicine in Hershey, Pennsylvania used cells isolated from mice to compare the effects of all-trans retinoid acid (ATRA) on CD4+ and CD8+ Treg cell development. The results showed that while all-trans retinoic acid promoted CD4+Foxp3+Treg development and function, it did not boost function and differentiation of human CD8+Foxp3+Treg. The researchers concluded that CD4+Treg treated with all-trans retinoid acid (ATRA) can be used for treatment of organ transplantation and autoimmune diseases. It is said that in their studies, Vitamin A has no known side effects, especially when used according to its recommended dosages. Vitamin A is well-tolerated by people unlike some immunomodulating drugs which may have toxic side effects on the body. More studies are needed to find out whether Vitamin A can really modulate immune response in autoimmune diseases and transplant recipients.
To know more about the other health benefits of Vitamin A, feel free to read our other articles on this site.