Posted by Ramneek S. Bhogal, DC, DABCI on Mar 30, 2021 4:57:15 PM
Vitamin A is a fat-soluble vitamin that plays a crucial role in keeping your body happy and healthy year-round.* Best-known for its support of firm, beautiful skin, hair, and nails, vitamin A is also integral to eye health, fetal development, and a well-functioning immune system.*
Interestingly, vitamin A does not refer to a single nutrient—it is actually a term used for a group of compounds called provitamin A and preformed vitamin A, which is found in both plant and animal sources. This essential group of compounds is highly important for many aspects of human health.*
Provitamin A carotenoids include beta-carotene, beta-cryptoxanthin, and alpha-carotene. These three forms of vitamin A are known as inactive forms found in plant foods. Preformed vitamin A is the active form found in animal products and is more bioavailable to the body. These compounds include retinal, retinoic acid, and retinol.
Inactive forms of vitamin A can be converted to active forms in the small intestine, and beta-carotene is the most common inactive form that the body transforms. However, not everybody is able to efficiently and effectively convert inactive forms of vitamin A; inadequacy tends to be higher in vegetarians and vegans, as well as people with gut health issues.
Provitamin A can be obtained from beef and lamb liver, cod liver oil, mackerel, salmon, tuna, goat cheese and other cheeses, butter, and eggs. Preformed vitamin A is found in sweet potato, winter squash, kale, collard greens, carrots, turnip greens, red bell pepper, Swiss chard, and spinach. Several fruits also contain smaller amounts of preformed vitamin A, such as mango, cantaloupe, red grapefruit, watermelon, papaya, apricot, and tangerines.
One of vitamin A’s most important health benefits is its support of the immune system, Vitamin A strengthens the body’s mucosal barriers in the eyes, gut, and lungs that trap bacterias and other compounds.*
Immunoregulatory behavior seems to be the least understood mechanism of how vitamin A works in the body, but we do know that it plays a key role in mucin production and supports the growth and distribution of T-cells, a type of white blood cell that protects the body from foreign invaders.* Adequate vitamin A levels also help to support a robust immune system by modulating macrophage production.*
Along with boosting immune function, vitamin A may also provide the following health benefits.*
Vitamin A is best-known for its role in skin support, as it supports skin integrity by acting as a core epithelial-building block for surface tissue maintenance.* In fact, vitamin A is known as the epithelial vitamin, since it helps strengthen the tissues in the outer surfaces of blood vessels and organs, along with inner cavities.* Specifically, vitamin A supports lungs, bladder, skin, and ear epithelial tissue*.
While the mechanisms aren’t entirely clear, it also seems that vitamin A inadequacy might be one underlying factor in cases of acne, possibly due to an overproduction of keratin in hair follicles, which can lead to blockages.
Due to its ability to support surface tissue maintenance, vitamin A also supports the health of eye tissue and protects the retina.* Lack of adequate vitamin A can contribute to night blindness, as this nutrient is a precursor to rhodopsin, a light-sensitive protein essential for night vision.
Hair and Nails
Like many other cells in the body, hair also requires vitamin A for proper growth and keratinization, and studies suggest that adequate vitamin A can promote hair growth and retention.* Vitamin A is also a cofactor for healthy collagen production, which is essential for skin elasticity and strong nails.*
Reproduction and Fetal Development
Vitamin A contributes to a more stable cell maturation process, helping to protect cells from free radical damage during higher risk stages of their maturation cycle, which is of great importance during fetal development.* While sufficient vitamin A levels are important for fetal development, too much vitamin A during pregnancy can be toxic, so working with a doctor to achieve the right balance is key.
Because it is foundational to many bodily functions and optimal immune health, it’s important to stay vigilant about your vitamin A intake and work with your practitioner to test serum levels over time. If you are a pregnant woman, always avoid supplementation or high levels of vitamin A-rich foods before discussing it with your provider.
 Tang G. Bioconversion of dietary provitamin A carotenoids to vitamin A in humans. Am J Clin Nutr. 2010 May;91(5):1468S-1473S. doi: 10.3945/ajcn.2010.28674G. Epub 2010 Mar 3. PMID: 20200262; PMCID: PMC2854912.
 AIP Conference Proceedings 1744, 020049 (2016); https://doi.org/10.1063/1.4953523 Published Online: 14 June 2016
 McCullough FS, Northrop-Clewes CA, Thurnham DI. The effect of vitamin A on epithelial integrity. Proc Nutr Soc. 1999 May;58(2):289-93. doi: 10.1017/s0029665199000403. PMID: 10466169.
 Alfred Sommer, Vitamin A Deficiency and Clinical Disease: An Historical Overview, The Journal of Nutrition, Volume 138, Issue 10, October 2008, Pages 1835–1839, https://doi.org/10.1093/jn/138.10.1835
 Mejia LA, Hodges RE, Rucker RB. Clinical signs of anemia in vitamin A-deficient rats. Am J Clin Nutr. 1979 Jul;32(7):1439-44. doi: 10.1093/ajcn/32.7.1439. PMID: 453058.
Subscribe to get email notifications about the latest Davinci blog posts