Postpartum depression (PPD) is a major depressive disorder that most often emerges within 6 to 12 weeks of delivery, but can happen any time up to 1 year after birth. In developed countries, the incidence of postnatal depression is about 10-15% in adult women depending upon the diagnostic criteria, timing of screening and screening instruments used. Mothers with depressive symptoms have been found to have more complex behavioral contacts with their children; this situation can damage family relationships, and even leads to infanticide. Various pathophysiologies are proposed for postpartum depression: Nutritional deficiencies, iron deficiency anemia, rapid decrease in the levels of reproductive hormones following delivery, alterations in hypothalamic–pituitary–adernocortical mechanism and alterations in neurotransmitter levels. Among pathophysiologies of postpartum depression, the role of trace elements is highlighted. The purpose of this review is to assess the role of trace elements including zinc, magnesium, iron and copper in PPD. Zinc as a trace element has the second highest concentration of all transition metals in the brain, and its deficiency is associated with behavioral disturbances. Lower zinc blood concentration was found in women with postpartum depression. Another trace element, magnesium, also influences the nervous system via its actions on the release and metabolism of neurotransmitters. Various studies have focused on antidepressant-like effects of magnesium and its deficiency has been reported in depression. Depletion of magnesium stores during pregnancy is hypothesized to be the cause of postpartum depression. Iron deficiency is the most common single nutrient deficiency in the world. There is an association between anemia and depressive disorders. Copper has been recognized as an essential element for many years. Iron also plays a vital role in neurological disorders and its levels are relevant to postpartum depression. Involvement of trace elements can be seen in pathophysiologies of PPD in different ways. Therefore, trace element supplementation can be an alternative treatment for patients with PPD.

During dialysis some trace elements can accumulate while others may be removed from blood, leading to deficiency of some trace elements. For evaluating changes of serum trace elements in children on maintenance hemodialysis we measured copper (Cu), zinc (Zn), cobalt (Co), manganese (Mn), chromium (Cr) and nickel (Ni) in 3 groups of children: Group 1, children with CRF who were on regular hemodialysis; Group 2, children with CRF who were on conservative management, and Group 3, healthy children. For evaluating the impact of duration of dialysis on serum trace elements, group 1 patients were divided into two subgroups: A, patients who were on hemodialysis therapy for shorter than 18 months, and B, patients who were on hemodialysis therapy for longer than 18 months. The technique used for measurement of trace elements was PIXE (Proton Induced X-ray Emission). Mean serum levels of Zn, Mn, and Ni in group 1 were lower than group 2 and group 3. There were not significant differences in serum levels of Zn, Mn and Ni between group 2 and 3. The differences in serum levels of Cr, Co and Cu among 3 groups were not significant. The serum levels of Zn, Mn and Ni were significantly lower in subgroup B compared to subgroup A. Correlation test showed that there were an inverse linear relation between the period of hemodialysis and serum levels of Zn, Mn and Ni. Chronic hemodialysis leads to abnormalities of some trace elements in children, and these derangements increase with duration of hemodialysis.

The dietary requirement for an essential trace element is an intake level which meets a specified criterion for adequacy and thereby minimizes risk of nutrient deficiency or excess. Disturbances in trace element homeostasis may result in the development of pathologic states and diseases. This article is an update of a review article “ trace elements in Human Nutrition-A Review” previously published in 2013. The previous review was updated to emphasis in detail the importance of known trace elements so far in humans’ physiology and nutrition and also to implement the detailed information for practical and effective management of trace elements’ status in clinical diagnosis and health care situations. Although various classifications for trace elements have been proposed and may be controversial, this review will use World Health Organization( WHO) classification as previously done. For this review a traditional integrated review format was chosen and many recent medical and scientific literatures for the new findings on bioavailability, functions, and state of excess/deficiency of trace elements were assessed. The results indicated that for the known essential elements, essentiality and toxicity are unrelated and toxicity is a matter of dose or exposure. Little is known about the essentiality of some of the probably essential elements. In regard to toxic heavy metals, a toxic element may nevertheless be essential. In addition, the early pathological manifestations of trace elements deficiency or excess are difficult to detect until more specific pathologically relevant indicators become available. Discoveries and many refinements in the development of new techniques and continual improvement in laboratory methods have enabled researchers to detect the early pathological consequences of deficiency or excess of trace elements. They all are promises to fulfill the gaps in the present and future research and clinical diagnosis of trace elements deficiencies or intoxications. However, further investigations are needed to complete the important gaps in our knowledge on trace elements, especially probably essential trace elements’ role in health and disease status.