Studies on Health Effects
Vitamin A is involved in many physiological functions and processes
"Improvement of vitamin A status in young child populations … leads to a reduction in all-cause mortality rates of about 23 percent"
United Nations, 1993
"Improved vitamin A nutriture would be expected to prevent approximately 1.3-2.5 million deaths annually among children aged under 5 years."
WHO Bulletin, 1992
Excellent information about the health effects of vitamin A available at the «Sight and Life» website in their Manual on Vitamin A Deficiency Disorders .
Vision and good health go together with a bright smile. Impaired vision, a terrible condition in itself, is but one manifestation of the disorders caused by vitamin A deficiency (VAD). More than one million children a year die as a consequence of a number of diseases precipitated by VAD.
Vitamin A is involved in:
- Vision (night, day, colour)
- Epithelial cell integrity against infections
- Immune response
- Haemopoiesis (red blood cell production)
- Skeletal growth
- Fertility (male and female)
In keratomalacia the hyperkeratotic epithelium has become soft and may thus become secondarily infected.
Retinol content in some natural sources
μg RE per 100 g
|dark green leafy
|red palm oil||30,000|
|cod liver oil||18,000|
Carotenoid content alone is not sufficient to tell how much will be taken up by the body, because other factors affect the bioavailability of carotenoids in the food, ie, carotenoid species, concentration, the food matrix, dietary fat, and also the health status of the person, eg, presence of parasites.
This world map from «Sight and Life» shows the impressive spread of clinical and subclinical VAD. brown, clinical; red, acute subclinical; orange, subclinical.
All developing countries are affected by multiple micronutrient deficiencies. In the case of vitamin A the most affected regions are Africa and SE Asia.