Vitamin A is an essential vitamin required for vision, gene transcription, boosting immune function, and great skin health.
A deficiency of vitamin A can lead to blindness and increased viral infection, however, deficiency is only considered a problem in developing countries where it is a leading cause of blindness in children.
Overconsumption of vitamin A can lead to jaundice, nausea, loss of appetite, irritability, vomiting, and even hair loss.
About The Types of Vitamin A and Retinol Equivalents
Vitamin A is available to humans in 2 ways: preformed vitamin A and carotenoids.
Carotenoids, like beta-carotene, are found in plant foods and have to be converted by the body into vitamin A. (2)
Preformed vitamin A is found in animal food sources like liver, meat, fish, and dairy. Like carotenoids, the preformed vitamin A also needs to be metabolized by the body into an active form of vitamin A. (2)
Solving the Vitamin A Problem: Since vitamin A comes in many forms, starting from July 2018 large US food producers will report vitamin A values in retinol activity equivalents (RAE) of vitamin A. The new daily value for Vitamin A RAE will be 900μg per day. (2,3)
High vitamin A foods include sweet potatoes, carrots, fish (tuna), winter squashes, dark leafy greens, cantaloupe, lettuce, bell peppers, broccoli, and grapefruit. The current daily value for Vitamin A is 900μg of retinol activity equivalents (RAEs).
Increased Protection from Bacterial and Viral Infections - Vitamin A is essential for healthy surface liningsof the eyes, mucous membranes, respiratory, urinary, and intestinal tracts.3-6
Proper Immune Functioning - Vitamin A is essential to regulate the immune system, and plays a key role in making white blood cells which fight off infections in the body.4,5,7-9
Cancer Protection (*Food Sources Only) - Studies suggest beta-carotene and vitamin A lower risk of many types of cancer.10 This effect could mainly be from a diet high in vegetables and not from supplements. VitaminA supplements have been shown to increase risk of cancer.11-13
High Risk Groups for a Vitamin A Deficiency
Alcoholics - Excessive consumption of alcohol can deplete levels of vitamin A in the body, and even moderate consumption can interfere with vitamin A absorption.
People with Long Term Problems Absorbing Fat - Problems absorbing fat in the long term can lead to diarrhea and vitamin A deficiency.This includes people with:
Celiac disease - Gluten Intolerance
Crohn's disease - Inflammatory Bowel Disease
Pancreatic disorders - The pancreas releases enzymes for proper digestion of fats
Cystic Fibrosis - Leads to a pancreatic disorder and improper absorption of fats
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Ross DA. Vitamin A and public health: Challenges for the next decade. Proc Nutr Soc 1998;57:159-65.
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de Pee S, West CE. Dietary carotenoids and their role in combating vitamin A deficiency: A review of the literature. Eur J Clin Nutr 1996;50 Suppl 3:S38-53.
Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press, Washington, DC, 2001.
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Ross AC, Stephensen CB. Vitamin A and retinoids in antiviral responses. FASEB J 1996;10:979-85.
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Albanes D, Heinonen OP, Taylor PR, Virtamo J, Edwards BK, Rautalahti M, Hartman AM, Palmgren J, Freedman LS, Haapakoski J, Barrett MJ, Pietinen P, Malila N, Tala E, Lippo K, Salomaa ER, Tangrea JA, Teppo L, Askin FB, Taskinen E, Erozan Y, Greenwald P, Huttunen JK. Alpha-tocopherol and beta-carotene supplement and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: Effects of base-line characteristics and study compliance. J Natl Cancer Inst 1996;88:1560-70.
Redlich CA, Blaner WS, Van Bennekum AM, Chung JS, Clever SL, Holm CT, Cullen MR. Effect of supplementation with beta-carotene and vitamin A on lung nutrient levels. Cancer Epidemiol Biomarkers Prev 1998;7:211-14.
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