FOOD SECURITY - Science for Agriculture and Rural Development in Low-income Countries - page 34

intergenerational cycle of malnutrition. Persisting malnutrition leads to the vicious
circle of hunger, poverty, and continued underdevelopment. Weight for age (WFA),
finally, is an easy to measure indicator and is therefore often reported. However, it is
difficult to judge whether low values result from chronic or acute malnutrition.
Micronutrient deficiencies (qualitative malnutrition)
Micronutrient deficiencies, often referred to as hidden hunger, are the world's most
threatening nutritional problems, especially because of the associated sub-clinical
changes in physiology that have a strong impact on health and functioning of large
numbers of people. Micronutrient deficiencies, visible in the ultimate clinical symp-
toms, are considered just the 'top of the iceberg' in terms of prevalence. For many
vitamins and minerals, deficiencies with associated sub-clinical physiological
changes may occur. Three micronutrients show such high prevalence that they are
considered a public health problem, i.e., Vitamin A, iron and iodine. In the follow-
ing, each of these will be discussed, with consequences and possible interventions.
Vitamin A
The typical first noticeable symptom of Vitamin A deficiency is night blindness. In
later stages, the epithelial tissue of the eyes is affected and infections of the cornea
can occur, leading to corneal ulcers and scar tissue after healing, ultimately leading
to irreversible blindness (xerophthalmia). However, of much greater importance is
sub-clinical Vitamin A deficiency, undermining the condition of the epithelial tissue
of all parts of the body and leading to higher susceptibility for infections and infectious
diseases. Since Vitamin A also plays a role in fighting infections, infectious diseases
further deplete body stores of Vitamin A, leading to a vicious circle of undermined
immune systems, enhanced susceptibility to infections, further depletion of Vitamin
A stores, etc. The relation between Vitamin A deficiency and prevalence of measles
is notorious.
At global scale, 140 million pre-school children (2-5 years of age) are Vitamin
A-deficient, of which every year 250,000-500,000 go blind, half of whom die within
12 months after loosing sight (because of the reduced immune response due to the
low Vitamin A status). Vitamin A-deficient children that do not suffer (as yet) from
blindness will have severely reduced immunity against infections, and thus suffer
from sub-optimal health.
Vitamin A deficiency is not only a problem of young children. Over 7 million
pregnant women suffer from night blindness and Vitamin A deficiency, because of
their increased need during pregnancy and lactation. Vitamin A deficiency in pregnant
women is a precursor of maternal mortality, as shown by a reduction by almost half,
following supplementation with Vitamin A.
Vitamin A naturally occurs in foods of animal origin and is fat-soluble. It can
also be synthesized in the body from beta-carotene, the yellow pigment in green
leafy vegetables and orange-fleshed fruits and vegetables. However, bio-availability
from fruits and vegetables is limited. Vitamin A can be added to (fatty) foods
(fortification), such as cooking oil and margarine. An alternative is semi-annual