All diseases, disorders, and deficiencies have a cause, usually a combination of environmental and biological factors. In the case of micronutrient deficiencies, the cause seems obvious—the individual’s body is not getting enough of the nutrient (albeit a minute quantity). Although the direct cause is easy to identify, there are many surrounding factors that affect how an individual gets enough of a needed nutrient—there are dietary, socio-economic, cultural, health, and other factors involved.

Now consider iron deficiency, as an example case. A mother does not consume adequate iron because her family does not eat meat. This mother, therefore, does not absorb enough from the other non-meat sources she eats because the meat source of iron (heme) is not available to enhance absorption from non-meat (non-heme) sources. Also, she usually follows the practice of drinking tea with each meal, which further inhibits absorption of the dietary iron. She usually experiences heavy menstruation, which leads to blood/ iron loss, causing anemia. The anemia causes her weakness, fatigue, and a loss appetite. Now she is eating less and she consumes even smaller quantity iron containing foods. If this woman were to become pregnant, then the fetus would require more iron from the mother, she would have hemodilution from the hormone changes, and she and the baby might suffer complications or even death during delivery. This is just one example to illustrate the many causes for micronutrient deficiencies. Determining risk for a deficiency requires a closer look, but a balance in that pertinent data must be carefully selected.

The goal in a health and nutrition survey is to collect relevant information that will be used in analysis for program planning. Very large national surveys with a broad range of nutrition data were sort of outdated in the mid-70’s when more simplified surveys started becoming preferred by large international agencies. These smaller surveys were more often local (whereas many before were national) and included only anthropometry, dietary and SES indicators, some qualitative information, and possibly a few questions related to micronutrients, such as IDD (Latham, Food and Nutrition in the Developing World, 1997). Since survey cost is an important issue, careful planning using previous experience and data collections should be used to select highly relevant, feasible indicators.

Mapping can often be a useful technique to visualize the areas experiencing micronutrient deficiencies, though a representative measurement of the deficiency must be chosen. The measurements are called indicators, such as goitre is used for iodine deficiency, nightblindness for vitamin A deficiency, and pallor for iron deficiency. It is very common to focus on clinical manifestations because it is relatively easy to measure something you can observe, although the clinical signs might develop only after other less visible harm has occurred. It is now recognized that an early detection (possibly by measuring for sub-clinical deficiency) is necessary to combat the "hidden" effects of the lacking nutrient. Many indicators, both clinical and sub-clinical have been developed for VAD, IDA, and IDD. Familiarity with the indicators and the cut-offs developed for these is essential for collecting and analyzing micronutrient data.

It is becoming more of a common practice to use the studies that have identified the high-risk populations (using the indicators mentioned), and in turn to provide preventative measures before the deficiency manifests. It was recognized in the 1980s that a deficiency in vitamin A leads to decreased immunity and therefore infection --and sometimes death-- in children before showing frank signs of deficiency, such as Bitot’s spots. Therefore in the 1990s, millions of pre-school age children around the world are receiving preventative doses as vitamin A capsules.

Look at the causes, manifestations, and indicators for VAD, IDA, and IDD using the links below, or found at the top of each page below the MN navigation bar.

All diseases, disorders, and deficiencies have a cause, usually a combination of environmental and biological factors. In the case of micronutrient deficiencies, the cause seems obvious—the individual’s body is not getting enough of the nutrient (albeit a minute quantity). Although the direct cause is easy to identify, there are many surrounding factors that affect how an individual gets enough of a needed nutrient—there are dietary, socio-economic, cultural, health, and other factors involved.

Considering iron deficiency, for example, a mother does not consume enough iron because her family does not eat meat (either for cultural or economic reasons). The mother, therefore, does not absorb enough from the other non-meat sources she eats due to the practice of drinking tea with each meal, which inhibits absorption. Additionally, she has heavy menstruation that leads to blood/ iron loss, therefore causing anemia. The anemia will cause her weakness, fatigue, and a loss appetite. Now eating less, she consumes even less iron containing foods. If this woman were to become pregnant, then the fetus would require more iron from the mother, she would have hemodilution from the hormone changes, and she and the baby might suffer complications or even death. This is just one (slightly complicated) example to illustrate that there are many causes for a micronutrient deficiencies when direct and underlying factors are considered. Determining risk for a deficiency requires a closer look.

When mapping out which areas are experiencing micronutrient deficiencies, it is necessary to have a measurement of the manifesting deficiency. The measurements are called indicators, such as goitre is used for iodine deficiency, nightblindness for vitamin A deficiency, and pallor for iron deficiency. It is very common to focus on clinical manifestations because it is relatively easy to measure something you can observe, although the clinical signs might develop only after other less visible harm has occurred. It is now recognized that an early detection (possibly by measuring for sub-clinical deficiency) is necessary to combat the "hidden" effects of the lacking nutrient. Many indicators, both clinical and sub-clinical have been developed for VAD, IDA, and IDD. Familiarity with the indicators and the cut-offs developed for these is essential for analyzing micronutrient data.

It is becoming more of a common practice to use the studies that have identified the high-risk populations (using the indicators mentioned), and in turn to provide preventative measures before the deficiency manifests. It was recognized in the 1980s that a deficiency in vitamin A leads to decreased immunity and therefore infection --and sometimes death-- in children before the child would show frank signs of deficiency, such as Bitot’s spots. Therefore in the 1990s, millions of pre-school age children around the world are receiving preventative doses as vitamin A capsules.

Use the links in red at the top to see the specifics for VAD, IDA, IDD.