Vitamin A

Vitamin A

Vitamin A is a fat-soluble vitamin that acts as an antioxidant in the body. It is found in two forms:

Preformed in animal products like meat, eggs, and dairy
Beta-carotene found in plant based foods

The body converts beta-carotene into vitamin A. Among the carotenoids (yellow, orange, or red fat-soluble pigments) that can be converted to vitamin A, beta-carotene is the most abundant and effective. Aside from being a source of vitamin A, beta-carotene plays many different roles in the body that are critical for human survival.

Benefits of Vitamin A

As an antioxidant, vitamin A offers extensive benefits that range from protecting the body against damaging molecules called free radicals to lowering your risk for fatal illnesses.

Improves Vision and Prevents Eye Diseases

A major clinical trial, the Age Related Eye Disease Study (AREDS), revealed that beta-carotene supplementation at a dose of 15 mg was able to slow the progression of age-related macular degeneration.^[1] This eye disease happens when the macula, which controls central vision, starts to break down. In addition, vitamin A is one of the required precursors for the formation of the photopigment rhodopsin, which helps you see better at night.^[2]

Prevents Various Cancers

Several observational studies in smokers and non-smokers, found that higher intakes of carotenoids from fruits and vegetables are associated with a lower risk of lung cancer.^[3]

Reduces Asthma Attacks

Taking beta-carotene by mouth seems to reduce symptoms of asthma and prevent impairment of lung function by counteracting the effects of damaging free radicals and reducing external attacks (bacteria, virus, or toxins).^[4]

Lowers Risk for Heart Diseases

In vitro studies indicate that carotenoids can prevent plaque build-up inside your arteries (atherosclerosis), a condition that is associated with progression of heart diseases.^[5]  

Prevents Inflammatory Disorders

One study revealed that beta-carotene possesses anti-inflammatory activity by functioning as a potential inhibitor of several inflammatory pathways, probably due to its antioxidant activity.^[6] Therefore, beta-carotene can be beneficial in arthritis, bronchitis and other inflammatory disorders.

Boosts Immune Function

Clinical trials have found that beta-carotene supplementation boosts the production of white blood cells (WBC) and enhances the activity of natural killer cells (NK).^[7-8] WBC and NK both help in fighting infections and harmful foreign bodies such as virus, bacteria and toxins.

Essential for Healthy Skin

In one study assessing the effects of 2 different doses of beta-carotene supplementation in 30 healthy female subjects over the age of 50 years, low-dose beta-carotene was able to improve facial wrinkles and skin elasticity.^[9]  

References:

1. Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev. 2012 Nov 14;11:CD000254. doi: 10.1002/14651858.CD000254.pub3.
2. Wald G. Molecular basis of visual excitation.  Science  1968;162(850):230-9.
3. Johnson EJ, Russell RM. Beta-Carotene. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. London and New York: Informa Healthcare; 2010:115-20.
4. Riccioni G, Barbara M, Bucciarelli T, Di ilio C, D’orazio N. Antioxidant vitamin supplementation in asthma. Ann Clin Lab Sci. 2007;37(1):96-101.
5. Pavia SA, Russell RM. Beta-carotene and other carotenoids as antioxidants. J Am Coll Nutr 1999; 18:426–33.
6. Bai SK, Lee SJ, Na HJ, et al. beta-Carotene inhibits inflammatory gene expression in lipopolysaccharide-stimulated macrophages by suppressing redox-based NF-kappaB activation. Exp Mol Med. 2005;37(4):323-34.
7. Villamor E, Fawzi WW. Effects of Vitamin A Supplementation on Immune Responses and Correlation with Clinical Outcomes. Clinical Microbiology Reviews. 2005;18(3):446-464. doi:10.1128/CMR.18.3.446-464.2005.
8. Stephensen CB. Vitamin A, infection, and immune function. Annu Rev Nutr. 2001;21:167-92.
9. Cho S, Lee DH, Won CH, et al. Differential effects of low-dose and high-dose beta-carotene supplementation on the signs of photoaging and type I procollagen gene expression in human skin in vivo. Dermatology (Basel). 2010;221(2):160-71.