Lower serum magnesium concentration is associated with diabetes, insulin resistance, and obesity in South Asian and white Canadian women but not men.

BACKGROUND: A large proportion of adults in North America are not meeting recommended intakes for magnesium (Mg). Women and people of South Asian race may be at higher risk for Mg deficiency because of lower Mg intakes relative to requirements and increased susceptibility to diabetes, respectively. OBJECTIVE: This study compared serum Mg concentrations in South Asian (n=276) and white (n=315) Canadian women and men aged 20-79 years living in Canada's Capital Region and examined the relationship with diabetes, glucose control, insulin resistance, and body mass index. RESULTS: Serum Mg concentration was lower in women of both races and South Asians of both genders. Racial differences in serum Mg were not significant after controlling for use of diabetes medication. A substantial proportion of South Asian (18%) and white (9%) women had serum Mg <0.75 mmol/L indicating hypomagnesemia. Use of diabetes medication and indicators of poorer glucose control, insulin resistance, and obesity were associated with lower serum Mg in women, but not in men. CONCLUSIONS: These results suggest that the higher incidence of diabetes in South Asians increases their risk for Mg deficiency and that health conditions that increase Mg requirements have a greater effect on Mg status in women than men.

Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality.

Dietary antinutritional factors have been reported to adversely affect the digestibility of protein, bioavailability of amino acids and protein quality of foods. Published data on these negative effects of major dietary antinutritional factors are summarized in this manuscript. Digestibility and the quality of mixed diets in developing countries are considerably lower than of those in developed regions. For example, the digestibility of protein in traditional diets from developing countries such as India, Guatemala and Brazil is considerably lower compared to that of protein in typical North American diets (54-78 versus 88-94 %). Poor digestibility of protein in the diets of developing countries, which are based on less refined cereals and grain legumes as major sources of protein, is due to the presence of less digestible protein fractions, high levels of insoluble fibre, and/or high concentrations of antinutritional factors present endogenously or formed during processing. Examples of naturally occurring antinutritional factors include glucosinolates in mustard and canola protein products, trypsin inhibitors and haemagglutinins in legumes, tannins in legumes and cereals, gossypol in cottonseed protein products, and uricogenic nucleobases in yeast protein products. Heat/alkaline treatments of protein products may yield Maillard reaction compounds, oxidized forms of sulphur amino acids, D-amino acids and lysinoalanine (LAL, an unnatural nephrotoxic amino acid derivative). Among common food and feed protein products, soyabeans are the most concentrated source of trypsin inhibitors. The presence of high levels of dietary trypsin inhibitors from soyabeans, kidney beans or other grain legumes have been reported to cause substantial reductions in protein and amino acid digestibility (up to 50 %) and protein quality (up to 100 %) in rats and/or pigs. Similarly, the presence of high levels of tannins in sorghum and other cereals, fababean and other grain legumes can cause significant reductions (up to 23 %) in protein and amino acid digestibility in rats, poultry, and pigs. Normally encountered levels of phytates in cereals and legumes can reduce protein and amino acid digestibility by up to 10 %. D-amino acids and LAL formed during alkaline/heat treatment of lactalbumin, casein, soya protein or wheat protein are poorly digestible (less than 40 %), and their presence can reduce protein digestibility by up to 28 % in rats and pigs, and can cause a drastic reduction (100 %) in protein quality, as measured by rat growth methods. The adverse effects of antinutritional factors on protein digestibility and protein quality have been reported to be more pronounced in elderly rats (20-months old) compared to young (5-weeks old) rats, suggesting the use of old rats as a model for assessing the protein digestibility of products intended for the elderly.

Nuclear factor kappa B activation and regulation of cyclooxygenase type-2 expression in human amnion mesenchymal cells by interleukin-1beta.

Interleukin-1beta (IL-1beta) has been shown in numerous studies to increase prostaglandin (PG) output by up-regulating the expression of cyclooxygenase-2 (COX-2), a rate-limiting enzyme in PG synthesis. In this study, we investigated the possible role of the nuclear factor kappa B (NFkappaB) in IL-1beta signaling, leading to the expression of COX-2 in human amnion cell culture. Fetal amnion was obtained following vaginal delivery and digested with collagenase, and the subepithelial (mesenchymal) cells were isolated. Cultures were characterized with antisera to keratin (epithelial cells) and vimentin (mesenchymal cells). Confluent cells were stimulated with human recombinant IL-1beta, and activation of NFkappaB was assessed by measuring changes in the inhibitory protein IkappaB (total IkappaB and phosphorylated IkappaB) using Western blot analysis as well as by nuclear binding of NFkappaB using an electrophoretic mobility shift assay. COX-2 protein levels were determined by Western blot analysis. After 5 min of stimulation with IL-1beta, phosphorylated IkappaB began to appear, 90% of which was degraded within 15 min. This was temporally associated with decreased total IkappaB and increased nuclear NFkappaB DNA-binding activity. In the IL-1beta-treated group, COX-2 protein began to increase after 6 h; this response was time-dependent, with a significant increase until 24 h after IL-1beta stimulation. When NFkappaB translocation was blocked by using SN50 (a cell-permeable inhibitory peptide of NFkappaB translocation), the synthesis of COX-2 protein was inhibited. These results suggest that NFkappaB is involved in the IL-1beta-induced COX-2 expression in the mesenchymal cells of human amnion.