In the nations of the West the average age has risen largely due to a significant decrease in the risk of death in childhood. As more people survive childhood and live to their maximum age, it pushes the average age upwards. This is often erroneously used to show that people are living longer in Western countries, which is not true, as the maximum age has not changed much in over 100 years. The reason that childhood death rates have fallen is largely due to reductions in childhood infections, which are a major cause of childhood morbidity and mortality throughout the World. Improvements in sanitation and hygiene have undoubtedly reduced this risk in the developed nations, but improvements in nutrition have also played a significant role. Vitamin A is required by the immune system and low levels of the vitamin are known to increase the risk of infection through gastrointestinal and respiratory infections. Morbidity in school aged children in many developing countries are therefore associated with low vitamin A intakes.
For example, the morbidity of school age children in developing countries has been investigated. In one study1, researchers investigated the morbidity of school children in Bogota, Colombia. The researchers assessed the children for 1 year and in this time recorded all cases of diarrhea with vomiting, coughing with fever, earache or ear discharge with fever, and doctors visits. The vitamin A status of the children was also measured. Adequate vitamin A status was defined as a plasma levels above 30 μg/dL. The results of the study showed that vitamin A deficiency (less than 10 μg/dL) was associated with an increased risk of diarrhea and vomiting and an increased risk of coughing with fever. Each additional 10 μg/dL of vitamin A plasma levels increase was associated with an 18 % decrease in diarrhea with vomiting, a 10 % decrease in coughing with fever and 6 % fewer doctors visits. The results also showed that for every 1 % increase in haemoglobin there was a 17 % reduction in ear infections and 5 % fewer doctors visits.
These results suggest that poor vitamin A status is a risk factor for childhood infections. This may partly explain the high mortality rates for children in developing nations. Vitamin A deficiencies still cause millions of cases of childhood blindness every year, and this along with infections leads to much unnecessary suffering for children. Traditionally it has been thought that poor vitamin A status most negatively affects children below the age of 5, but these data show that children above the age of 5 are also at risk (the children in this study were between the ages of 5 and 12 years). The low haemoglobin levels of some of the children in this study was likely due to iron deficiencies, which are the most common form of nutritional deficiency in the World. Iron is not protective of infection, but anaemia is a risk factor for poor immunity as evidenced by the increased infection rates associated with low haemoglobin levels. Both poor iron and vitamin A statuses may therefore increase the risk of infection in children.
RdB
