Nutritional aspects of manganese from experimental studies

In experimental animals, dietary manganese deficiency can result in numerou s biochemical and structural abnormalities. Deficient animals can be charac terized by impaired insulin production, alterations in lipoprotein metaboli sm, an impaired oxidant defense system, and perturbations in growth factor metabolism. if the deficiency occurs during early development there can be pronounced skeletal abnormalities and an irreversible ataxia. Several lines of evidence suggest that manganese deficiency may be a problem in some hum an populations. Manganese toxicity can also pose a significant health risk. In experimental animals, acute manganese toxicity can result in numerous b iochemical pathologies. However, the above occurs typically when the mangan ese is given via injection; most animals show considerable resistance to di etary manganese toxicosis. Similarly, confirmed cases of manganese toxicity in humans are currently restricted to cases of exposure to high levels of airborne manganese, and to cases when manganese excretory pathways are comp romised. (C) 1999 Inter Press, Inc.