Vitamin A

Alternative Names

Retinol, Retinal, Retinoic acid, Carotenoids, Palmatate, Acetate


Overview

Vitamin A is essential for the functions of all the organs within the body and is particularly important for growth and development. Vitamin A primarily helps with the maintenance of our vision, the growth and repair of cells, cell differentiation, maintaining the health of epithelial cells and protection against infection. Having sufficient amounts of vitamin A can help improve our immune systems, help to prevent infection; cancer and cardiovascular disease, and can be used to help treat symptoms of the common cold or the flu and osteoarthritis. Liver, raw carrots, squash, kale, mangoes and cantaloupe are all good sources of this vitamin.


Function

Maintenance of normal vision: Vitamin A is needed to help our eyes to function effectively. This vitamin forms the photosensitive pigments that absorb light and initiate the visual process. Vitamin A is used in the production of a chemical called visual purple, which helps us to see in dim lighting. Without the necessary amounts of vitamin A night blindness can occur.

Cellular Involvement and Epithelial Health: The growth and repair of many body cells including bone, teeth collagen and cartilage relies on vitamin A. Vitamin A is also essential for a process called cell differentiation, in this process cells with an unspecified purpose are modified into various cells such as a liver cell, blood cell or a neuron, so that they can perform specific functions throughout the body. Since it plays a large role in cell development and differentiation, adequate vitamin A helps to ensure that the changes which occur in the cells and tissues during the fetal development take place normally. The health and formation of epithelial cells is also reliant on adequate amounts of vitamin A. These cells cover the internal and external surfaces of the body and found in the skin, lungs, developing teeth, gums, sex organs, glands and their ducts, and the nose. Many of these epithelial cells produce mucus which is necessary for our bodies to create lubrication for various surfaces and protect against any possible invading microorganisms.

Protection against Infection: Nicknamed “the anti-infective vitamin”, vitamin A plays an essential role in protecting the body from infection. It helps keep body surfaces healthy so they function as barriers to any possible invading micro-organisms. Vitamin A stimulates and enhances many of our immune functions including antibody responses and the activity of white blood cells such as T-helper cells and phagocytes. The immune enhancing properties of vitamin A promote the healing of infected tissues and increases resistance to infection.


Forms Available


Recommended Intake

Infants (average intake)

  • 0-6 months: 400 micrograms per day (mcg/day)
  • 7-12 months: 500 mcg/day

Children

  • 1-3 years old: 300 mcg/day
  • 4-8 years old: 400 mcg/day
  • 9-13 years old: 600 mcg/day

Adolescents and Adults

  • Males 14 years old and older: 900 mcg/day
  • Females 14 years old and older: 700 mcg/day

It is a good idea to consult a doctor for recommended amounts for pregnant women and other health factors that may change the level of Vitamin A necessary in the diet.


Deficiency

Eye: One of the earliest symptoms of vitamin A deficiency is night blindness, which occurs when the chemical visual purple is not produced. When there is a prolonged deficiency of vitamin A, a condition called xerophthalmia occurs. During this condition the eyes become dry, ulcers begin to appear on the cornea, the eyelids become swollen and sticky which ultimately leads to blindness.

Skin: a prolonged deficiency in vitamin A leads to thickened dry skin which is more prone to developing infections. This condition can lead to the development of small hardened bumps of a protein, known as keratin, around the hair follicles within the skin.

Immune system: Epithelial cells and surfaces are greatly affected by vitamin A deficiencies, causing an increase susceptibility to skin and respiratory infections. Along with epithelial cells, immune cells and antibody functions become affected which in return can lead to an increase in precancerous cells within the epithelial tissues of the mouth, lungs and throat. Vitamin A deficiencies are often seen in those with compromised immune systems like those who are HIV – positive.

Thyroid gland: Deficiencies in vitamin A can contribute to lower levels of active thyroid hormone, some symptoms can include lower body temperature, depression, difficulty with weight loss, headaches and lethargy.


Sources in the Diet

Vitamin A can be found in foods from animal origins such as beef liver or liverwurst, cod liver oil, some seafood such as sardines, butter, and some vegetables such as kale, raw carrots, mangoes, cantaloupe and apricots.


Recent Studies and Articles

Vitamin A and prostate cancer

http://medicalxpress.com/news/2013-04-vitamin-prostate-cancer.html

Vitamin A and skin cancer

http://www.easier.com/115114-vitamin-a-supplementation-could-cut-skin-cancer-risk.html

Vitamin A and the immune system

http://www.naturalnews.com/031778_vitamin_A_immune_system.html


Challenges Presented


Watson Products

E ACETATE 50% C.W.D. , 22 LB (10 KG) IP BAG
VITAMIN A 1.7 IU/GRM , 6 X 1KG CARTON


Sources

  1. [] – Reavley N. The New Encyclopedia of Vitamins, Minerals, Supplements and Herbs. New York, NY: M. Evans and Company, Inc.; 1998.
  2. [] – Nelms, M. Sucher, K. Lacey, K. Roth, S. Nutrition Therapy & Pathophysiology. 2 ed. New York, NY: Cengage Learning; 2011.
  3. [] – Crouch R, Kono K, Tang P. Role of Vitamin A in Retinal Diseases. Journal of the South Carolina Academy of Science. 2014. Vol. 12: Iss. 1, Article 3. http://scholarcommons.sc.edu/jscas/vol12/iss1/3/.
  4. [] – Boyle, Marie A. and Anderson Sara L. Personal Nutrition. 7th ed. Belmont, CA: Wadsworth/Thomson Learning; 2007.
  5. [0] – http://www.nlm.nih.gov/medlineplus/ency/article/002400.htm
  6. [0] – http://learn.genetics.utah.edu/content/begin/dna/transcribe/