A Global Challenge to Health
In its 2002 report, the World Health Organization (WHO) estimates that approximately 168 million children under five years of age are underweight, meaning they do not get enough nutrients to meet their bodys’ needs. Multiple micronutrient deficiencies, such as from iron, zinc, and vitamin A, are affecting the lives and health of billions of people in the developing world.
Micronutrients play an essential role in the metabolic processes of the human body, but are only required in small quantities.
Because of their essential role, when micronutrients are not sufficient from food in the diet, significant health problems can result.
Iron deficiency is the most prevalent nutritional deficiency worldwide. It is a major public health problem with adverse consequences particularly for women of reproductive age and for young children.
When there is not enough iron in the body, fewer red blood cells are produced. This reduces the capacity of the blood to transport oxygen. As a result, symptoms, ranging from fatigue and inability to concentrate, to impaired physical and cognitive development of children, can occur. Iron deficiency anaemia may also cause problems during pregnancy particularly in developing countries, where it can increase the risk of premature delivery, as well as the risk of maternal and foetal complications and death.
The most common reason for iron deficiency anaemia, especially among infants and children, is due to inadequate iron from food. Parasites, infections, stomach and digestive diseases, and blood loss during menstruation may also worsen anaemia.
Global Distribution of Iron Deficiency.
Zinc is an important nutrient. It is an essential part of many enzymes (a protein molecule that catalyzes chemical reactions in the body) and plays an important role in protein synthesis and cell division. The health consequences of zinc deficiency include, poor immune system function, growth retardation, and delayed sexual maturity in children. Zinc deficiency is caused by low intake and/or low absorption of bioavailable zinc. Diets low in meat and fish increase the risk of zinc deficiency, because zinc is poorly bioavailable in cereals.
Global Distribution of Vitamin A Deficiency.
Vitamin A Deficiency
Vitamin A is another essential nutrient in the human diet, contributing to the functioning of the retina, the growth of bone, and the immune response. Apart from preventable, irreversible blindness, vitamin A deficiency also causes reduced immune function, leading to an increased risk of severe infectious disease and anaemia. It also increases the risk of death during pregnancy for both the mother and foetus and after birth for the newborn.
Vitamin A deficiency occurs when too little vitamin A is taken in and absorbed from food. Vitamin A also comes from beta-carotene, a precursor found in fruits and vegetables, however, investigations have shown that beta-carotene is not as bioavailable as once thought, meaning that more must be eaten to get an adequate amount of vitamin A. An estimated 250 million pre-school children in developing countries are affected by Vitamin A deficiency, although severe deficiency that causes blindness is declining.
Bioavailability refers to how much of a given substance is in a form that can be readily used by the body.
In nutrition, it is not only important to have enough of a particular nutrient, but it must also be “available” to be used by the body