Unusual Micronutrient Deficiencies as Causes of Anemia.

Anemia due to micronutrient deficiencies has received little attention in public health and modern-day clinical practice. Increasing numbers of persons, mainly in low- and middle-income nations, are faced with malnutrition and malabsorption syndromes, giving rise to various micronutrient deficiencies that can lead to anemias refractory to treatment with iron, folate or vitamin B12. Though relatively uncommon, such underlying nutrient deficiencies may be difficult to recognize as they can coexist with more common causes and there may be few or no specific clinical characteristics pinpointing a particular micronutrient. The main examples of these micronutrients contributing to a small but important burden of anemia are other B-group vitamins, pyridoxine and thiamine, ascorbic acid, the fat-soluble vitamins, A and E and other trace elements such as copper, zinc and selenium. The following review highlights the current state of knowledge and the relevance of these micronutrient deficiencies in the broader context of nutritional anemia.