The importance of zinc for human health has been recognized since the early 1960s, but today there is little concern about zinc deficiency in developed countries. We measured the zinc concentration in hair from 28,424 Japanese subjects (18,812 females and 9,612 males) and found that 1,754 individuals (6.17 %) had zinc concentrations lower than the -2 standard deviations level (86.3 ppm) of its control reference range, which qualifies as zinc deficiency. A considerable proportion of elderlies and children (20 % or more) were found to have marginal to severe zinc deficiency. A minimum zinc concentration of 9.7 ppm was observed in a 51-year-old woman; this concentration was approximately 1/13 of the mean reference level. The prevalence of zinc deficiency in adults increased with aging from 1-2 % in the young to a peak of 19.7 % in the 8th decade of life, and decreased to 3.4 % or less in the longevities above 90-year-old. The prevalence of zinc deficiency in children aged 0–9 years was 29.9 % in males and 33.8 % in females.

In the study for 1,967 children with autistic disorders (1,553 males and 414 females), 584 individuals (29.7 %) were found deficient in zinc, and its deficiency rate in infantile group aged 0–3 years was 43.5 % in male and 52.5 % in female. Next to zinc, 347 (17.6 %) and 114 (5.8 %) individuals were deficient in magnesium and calcium, and 2.0% or less in the other essential metals such as iron, cupper or manganese. In contrast, 339 (17.2 %), 168 (8.5 %) and 94 (4.8 %) individuals were found suffering from high burden of aluminum, cadmium and lead, and 2.8 % or less from mercury and arsenic burden. These findings suggest that infantile zinc deficiency and toxic metal burdens may epigenetically play pivotal roles as environmental factors in the pathogenesis of autism spectrum disorders (ASDs) and that metallomics approach helps lead to early screening and intervention/treatment of the neurodevelopment disorders.

This review demonstrates that infant and elderly are liable to zinc deficiency and that many infants with autistic disorders are suffering from zinc deficiency and toxic metal burdens, suggesting the presence of “infantile time window” in neurodevelopment and probably for therapy. These findings suggest that early assessment and intervention of zinc deficiency is possibly effective for infants with autistic disorders and essential for normal development, health and longevity.

Methylglyoxal (MG) is a highly cytotoxic metabolite produced primarily as a byproduct of glycolysis, against which plants intrinsically possess protective systems. On the other hand, selenium (Se) has become an element of interest to many plant scientists owing to its vast array of beneficial roles in plant physiology. In this study, I have addressed MG-associated cellular response to Se supplementation in Arabidopsis thaliana. While the content of intracellular MG along with that of malondialdehyde, a molecular readout of cellular damage, was increased with the increase in exogenous MG, the dose-dependent increase of these unwanted compounds was significantly moderated in Se-supplemented seedlings as compared with plants without Se uptake. Assay of MG detoxifying enzymes revealed that activities of glyoxalase II and aldo-keto reductase were enhanced in the seedlings when supplemented with Se, with the induction being advanced in association with increasing MG dosage. Another assay was conducted for antioxidant enzyme; inhibition of the activity of ascorbate peroxidase by MG was alleviated on Se supplementation to the seedlings, and this favorable effect of Se intervention appeared more remarkablely for its chloroplast stromal isozyme than for its cytosolic isozyme, indicative of stroma-biased protective functions of Se in Arabidopsis seedlings. The present results show that a trace amount of Se contributes to MG detoxification in Arabidopsis thaliana, which presumably results at least in part from its positive regulation of the enzyme activities for MG metabolism and radical scavenging.