How Vitamin A Could Save Children's Lives, Vision

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Vitamin A supplements are inexpensive to make, easy to administer, could save more than 600,000 children’s lives per year, and also preserve their vision, according to a new joint study between experts from Pakistan and the United Kingdom. How does vitamin A work to save lives?

Vitamin A is critical for immune system function

The new study evaluated 43 trials that included 215,633 children ages 6 months to 5 years. In 17 of those trials, there was a 24 percent reduction in deaths when children were given vitamin A supplements compared with those who did not receive the nutrient.

Seven trials showed a 28 percent reduction in deaths associated with diarrhea among children who took vitamin A. The reviewers also found a 15 percent reduction in the incidence of diarrhea, a 50 percent reduction in measles, and a reduced prevalence of vision problems, including night blindness (68% less) and xerophthalmia (69% less). Xerophthalmia is excessive dryness and thickness of the conjunctiva and cornea that can eventually lead to blindness.

How does vitamin A cause these significant reductions in death and symptoms? Vitamin A is an umbrella term for several related compounds, including retinol, retinal, and retinoic acid, collectively known as retinoids. These are also referred to as preformed vitamin A, and they are found in animal foods.

Beta-carotene and other carotenoids are found in plants (e.g., fruits, vegetables, grains), and the body can convert them into retinol. They are referred to as provitamin A carotenoids.

Vitamin A is necessary for normal functioning of the immune system. Retinol and its metabolites maintain the integrity and function of skin and mucosal cells, which act as a barrier against infection. Vitamin A and retinoic acid are essential for immune response and fighting off infections. In addition, retinoids are required for the production of red blood cells, which transport oxygen throughout the body.

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The World Health Organization estimates that 190 million children age 5 and younger around the world are vitamin A deficient. Research shows that even children who are only mildly deficient in vitamin A are more likely to have respiratory diseases and diarrhea and a higher rate of death from infectious diseases compared with children who get a sufficient amount of vitamin A.

When children get an infection, their blood levels of retinol decline rapidly, which is believed to be associated with a decline in the production of retinol binding protein by the liver. The deficiency of vitamin A and the severity of the infection increase the chance of death from infectious disease.

Vitamin A, specifically retinol, is involved in a complex process that is critical for normal vision. If an inadequate amount of retinol is available to the retina, the result can be night blindness, which is an inability to adapt to the dark. Xerophthalmia is also a result of vitamin A deficiency.

Vitamin A deficiency occurs in areas of the world where adequate food is typically in short supply. Foods that provide preformed vitamin A include cheese, liver, eggs, and oily fish. Provitamin A carotenoids can be found in high levels in carrots, spinach, sweet potatoes, winter squash, and various greens.

Although vitamin A supplementation programs are ongoing around the world, they are not reaching all the children in need. According to Dr. Evan Mayo-Wilson from the University of Oxford, one of the study’s authors, “Until other sources are available, supplements should be given to all children who are at risk of vitamin A deficiency.” Reaching more children means saving more lives and vision.

SOURCES:
Field CJ et al. Journal of Leukocyte Biology 2002; 71(1): 16-32
Linus Pauling Institute
Mayo-Wilson E et al. British Medical Journal 2011; 343:d5094
Thurnham DI, Northroop-Clewes CA. Proceedings of the Nutrition Society 1999; 58(2): 449-57

Picture credit: Wikimedia Commons

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