L. Mallory Boylan

Arsenic and selenium in human hair

The selenium (Se) content of the diet and/or selenium supplements might have an ameliorating effect on arsenic (As) toxicity as recently shown by Wang et al. (1), Yang et al. (2), and as reviewed by Spallholz et al. (3). The underlying principles of the ameliorating effect is the complexation of Se with As forming the seleno-bis (S-glutathionyl) arsinium ion (4) excreted in bile and the complexation of Se with As in tissues forming nontoxic insoluble selenides (5,6). Addition protection afforded by Se supplementation from arsenicosis could be the elevation of glutathione peroxidase activity reducing the oxidative stress induced by As (7,8). The present study assessed the status of Se and As in hair by neutron activation analysis (NAA). Human hair samples were collected from the United States, Canada, The Peoples Republic of China (PRC), Bangladesh, and Nepal, the latter two countries now engaged in a struggle to find relief from human arsenicosis resulting from extensive domestic groundwater contamination by As. No statistically significant differences were observed in the samples between the Se and As content of hair from, Lubbock, Texas (USA) or Winnipeg, Canada. The concentration of As in all hair samples analyzed correlated (r=0.960, p<0.001) with the amount of As in the drinking water. Selenium levels in hair were highest from Nepal. The results demonstrate the viability of hair as a noninvasive biomonitor in assessing aspects of dietary Se and environmental As exposure. The hair data confirmed the known low intake of Se in the Keshan disease area of the PRC, the very high accumulation in hair of As from subjects consuming contaminated ground waters, and an adequate Se status in subjects from North America consuming municipal water of low As content. The high As content of hair from people in Bangladesh is the result of a high As consumption from contaminated water compounded by a less than desirable intake of Se (9). From Nepal, the As content of hair corresponded to the known low and high intake of As from contaminated groundwater. The very high Se content found in all hair samples from Nepal might be the result of the use of henna.

Selenium and arsenic content of agricultural soils from Bangladesh and Nepal

Arsenic (As) contamination of the available domestic drinking water from shallow aquifers to villagers in Bangladesh often exceeds the newest WHO standard of <10 µg As L−1 and the older Bangladeshi standard of <50 µg As L−1. An estimated 9.2 million shallow tube wells in Bangladesh deliver water to 97% of the rural population, placing an estimated 57 million people at risk for arsenicosis. The contamination of drinking water by As extends to W. Bengal, India and Nepal. The same shallow aquifers used for domestic water are also used to irrigate food crops, particularly rice. Irrigation adds As to soils and increases exposure of the population to additional As via foods consumed. Selenium (Se), an essential trace mineral found in soils, is absorbed by plants, entering the human food chain. It was suggested that a low dietary intake of Se may be contributing to the problem of human arsenicosis in Bangladesh. Dietary Se acts as a natural antidote to As by (1) accelerating As excretion, (2) sequestering As by complexation and (3) as an antioxidant component of the enzyme glutathione peroxidase that may counteract the prooxidant effects of As that contribute to arsenicosis and cancer. Analysis of 70 agricultural soil samples from Bangladesh by fluorimetry, ICP-AES and Neutron Activation Analysis showed the soils analyzed to be high in As (∼33 µg g−1) and biologically low in soluble Se (∼0.02 µg g−1). A low dietary intake of Se related to low soil content and this mineral in foods may be contributing to human arsenicosis in the Ganges–Brahmaputra delta.

Selenium content of rice, mixed plant foods and fish from Bangladesh

Selenium (Se), an essential trace mineral, is obtained by individuals from foods ingested and is necessary for 25 human proteins including the antioxidant family of glutathione peroxidases. Since plants are not known to require Se for growth, the quantity of this mineral in plant foods depends on the soluble Se in soils that is passively accumulated by plants. As all animals require Se, it is usually stored more uniformly and to a greater degree in animal than plant protein foods. Owing to the alluvial origin, high rainfall and flooding upon the soils of Bangladesh these soils appear to be low in measured soluble Se. These low levels of soluble Se in Bangladeshi soils reflect the low levels of Se in plant foods, rice and vegetables, staples of the rural and poor Bangladeshis diet. This study reports on the dry-weight content of Se found in samples of rice, other plant foods and fish from Bangladesh. Rice grain averaged 0.105 µg Se g−1 from Jessore and 0.212 µg Se g−1 from 5 other districts of Bangladesh. Gourds and potatoes from Jessore averaged 0.471 and 0.181 µg Se g−1 respectively. All other district plant foods averaged 0.26 µg Se g−1. All 7 different but unidentified species of fish sampled in Jessore and quantitated fluorimetrically averaged 1.318 µg Se g−1. Fish was the single highest food source of dietary Se per unit dry weight. Fish in particular, but also other animal foods, are likely to serve as better dietary sources of Se for the people of Bangladesh.

The Breastfed Infant’s Neurobehavioral Organization: Implications for Child Health and Cognitive Development

In this chapter we address whether and how breastfeeding contributes toward differences in the newborn infant’s neurobehavioral development. We then consider how differences of this nature might underlie or help account for some of known benefits of breastfeeding to infant health, and to possible advantages to intellectual development. The chapter reports that crying in the breastfed infant may be more frequent but of shorter duration and lesser intensity. Its relation to pain threshold is unclear. Findings on the breastfed infant’s sleep appear to suggest that sleep latency is shorter in duration, sleep intervals are of shorter duration, and arousability is greater. The breastfed infant’s sleep architecture may relate to child health. Some potential benefits relate to the incidence of SIDS, enuresis, and obesity. Breastfed newborns show more optimal social behavior, alertness, motor development, and neurological organization. Correspondingly, they have been found having longer heart rate, elevated heart period variability, and higher vagal tone, suggesting more optimal physiological organization. These strengths may contribute to superior cognitive skills, especially the ability to concentrate. They may also help advance cognitive and social development through their enhancing effects on parenting behavior.

High Dietary Intake of Vitamin E Causes Decreased Incidence of Early Atherosclerotic Lesions in Rats

Abstract LEARNING OUTCOME: To examine the role of high level vitamin E supplementation on the formation of atherosclerotic lesions. Elevated levels of oxidized low-density lipoprotein (LDL) is a major risk factor for atherosclerosis. Epidemiological evidence suggests that high dietary intake of vitamin E may decrease the risk for atherosclerotic vascular disease by protecting LDL from oxidation. To test this hypothesis, five groups of 12 rats were fed diets containing varying amounts of cholesterol and vitamin E. Plasma lipids [total cholesterol, high-density lipoprotein (HDL) and triglyceride (TG)] and the extent of aortic lesions were examined after 5 months of consumption of the diet. The results are summarized in the table below:Group 1Group 2Group 3Group 4Group 5Vitamin E60mg60mg300mg600mg2400mgTotal Chol. (mg/dl)1521016100612271232LDL(mg/ml)0.91.11.51.51.6HDL (mg/dl)124485069109TG (mg/dl)213408329347448Group 1:No Cholesterol/Cholic acidGroup 2-5:Cholesterol - 1.0%, Cholic acid 0.3% of the basal diet.Vitamin E:Given as tocopheryl acetate, mg/kg of diet. Key research findings are: Hypercholesterolemia and lower HDL cholesterol levels in the plasma were found to cause early atherosclerotic lesions in twice the number of rats (groups 4 and 5) as compared to rats (group 1) fed no cholesterol. The incidence of atherosclerotic lesions in the groups that received 600 & 2400mg of vitamin E was 50% lower than the group that received 300mg of vitamin E. It appears that high levels of vitamin E supplementation and HDL exert a protective effect which results in a decrease in atherosclerotic lesion formation.