...Ultrastructural findings were as follows. The number of myelinated axons of Zn-deficient rats at 4 and 7 weeks were significantly decreased and the myelin sheaths were significantly thinner in the Zn-deficient groups and in the recovery group. Unmyelinated axons were more numerous than in the control rats. Destruction of myelin and proliferation of glial cells were found in the optic nerves of Zn-deficient rats. This study suggests that the optic nerve needs Zn for the maintenance of its cell structure and even if Zn is supplied to the Zn-deficient rats, destruction of the myelin structure may continue. Zn-deficiency induces a decrease of myelinated nerve fibers, and it is thought that optic neuropathy in patients treated with some drugs such as ethambutol may be a secondary change due to Zn-deficiency following drug administration.
Low consumption of foods rich in bioavailable iron (Fe) and zinc (Zn) such as meat, particularly red meat, and high consumption of foods rich in inhibitors of Fe and Zn absorption, such as phytate, certain dietary fibers and calcium, cause Fe and Zn deficiencies. Neuropsychologic impairment is one of several potential outcomes of these deficiencies.
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