The Relevance of the Colon to Zinc Nutrition

Globally, zinc deficiency is widespread, despite decades of research highlighting its negative effects on health, and in particular upon child health in low-income countries. Apart from inadequate dietary intake of bioavailable zinc, other significant contributors to zinc deficiency include the excessive intestinal loss of endogenously secreted zinc and impairment in small intestinal absorptive function. Such changes are likely to occur in children suffering from environmental (or tropical) enteropathy (EE)—an almost universal condition among inhabitants of developing countries characterized by morphologic and functional changes in the small intestine. Changes to the proximal gut in environmental enteropathy will likely influence the nature and amount of zinc delivered into the large intestine. Consequently, we reviewed the current literature to determine if colonic absorption of endogenous or exogenous (dietary) zinc could contribute to overall zinc nutriture. Whilst we found evidence that significant zinc absorption occurs in the rodent colon, and is favoured when microbially-fermentable carbohydrates (specifically resistant starch) are consumed, it is unclear whether this process occur in humans and/or to what degree. Constraints in study design in the few available studies may well have masked a possible colonic contribution to zinc nutrition. Furthermore these few available human studies have failed to include the actual target population that would benefit, namely infants affected by EE where zinc delivery to the colon may be increased and who are also at risk of zinc deficiency. In conducting this review we have not been able to confirm a colonic contribution to zinc absorption in humans. However, given the observations in rodents and that feeding resistant starch to children is feasible, definitive studies utilising the dual stable isotope method in children with EE should be undertaken.G.L. Gopalsamy, D.H Alpers, H.J Binder, C.D. Tran, B.S. Ramakrishna, I. Brown, M. Manary, Elissa Mortimer and G.P. Youn

The effect of dietary resistant starch type 2 on the microbiota and markers of gut inflammation in rural Malawi children

BACKGROUND: Resistant starch (RS) decreases intestinal inflammation in some settings. We tested the hypothesis that gut inflammation will be reduced with dietary supplementation with RS in rural Malawian children. Eighteen stunted 3–5-year-old children were supplemented with 8.5 g/day of RS type 2 for 4 weeks. The fecal samples were analyzed for the microbiota, the microbiome, short chain fatty acids, metabolome, and proteins indicative of inflammation before and after the intervention. Subjects served as their own controls. RESULTS: The consumption of RS changed the composition of the microbiota; at the phylum level Actinobacteria increased, while Firmicutes decreased. Among the most prevalent genera, Lactobacillus was increased and Roseburia, Blautia, and Lachnospiracea incertae sedis were decreased. The Shannon H index at the genus level decreased from 2.02 on the habitual diet and 1.76 after the introduction of RS (P < 0.01). Fecal acetate concentration decreased, and fecal propionate concentration increased after RS administration (−5.2 and 2.0 μmol/g, respectively). Fecal calprotectin increased from 29 ± 69 to 89 ± 49 μg/g (P = 0.003) after RS was given. The lipopolysaccharide biosynthesis pathway was upregulated. CONCLUSIONS: Our findings do not support the hypothesis that RS reduces gut inflammation in rural Malawian children. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40168-015-0102-9) contains supplementary material, which is available to authorized users

The capacity of the fecal microbiota from Malawian infants to ferment resistant starch

In Low and Middle-Income Countries (LMIC), weaning is associated with environmentally acquired and inflammation-associated enteric disorders. Dietary intake of high amylose maize starch (HAMS) can promote commensal fermentative bacteria and drive the production of short chain fatty acids (SCFAs). By stabilizing commensal gut microbiology, and stimulating the production of anti-inflammatory metabolites, HAMS supplementation might therefore influence enteric health. However, the extent to which the gut microbiota of LMIC infants are capable of fermenting HAMS is unclear. We assessed the capacity of the fecal microbiota from pre-weaning and weaning Malawian infants to ferment HAMS and produce SCFAs using an in vitro fermentation model. Fecal microbiota from both pre-weaning and weaning infants were able to ferment HAMS, as indicated by an increase in bacterial load and total SCFA concentration, and a reduction in pH. All of these changes were more substantial in the weaning group. Acetate production was observed with both pre-weaning and weaning groups, while propionate production was only observed in the weaning group. HAMS fermentation resulted in significant alterations to the fecal microbial community in the weaning group, with significant increases in levels of Prevotella, Veillonella, and Collinsella associated with propionate production. In conclusion, fecal microbiota from Malawian infants before and during weaning has the capacity to produce acetate through HAMS fermentation, with propionate biosynthetic capability appearing only at weaning. Our results suggest that HAMS supplementation might provide benefit to infants during weaning

An economic case for providing free access to antiretroviral therapy for HIV-positive people in South Australia

Background As financial constraints can be a barrier to accessing HIV antiretroviral therapy (ART), we argue for the removal of copayment requirements from HIV medications in South Australia. Methods Using a simple mathematical model informed by available behavioural and biological data and reflecting the HIV epidemiology in South Australia, we calculated the expected number of new HIV transmissions caused by persons who are not currently on ART compared with transmissions for people on ART. The extra financial investment required to cover the copayments to prevent an HIV infection was compared with the treatment costs saved due to averting HIV infections. Results It was estimated that one HIV infection is prevented per year for every 31.4 persons (median, 24.0–42.7 interquartile range (IQR)) who receive treatment. By considering the incremental change in costs and outcomes of a change in program from the current status quo, it would cost the health sector $17 860 per infection averted (median,$13 651–24 287 IQR) if ART is provided as a three-dose, three-drug combination without requirements for user-pay copayments. Conclusions The costs of removing copayment fees for ART are less than the costs of treating extra HIV infections that would result under current conditions. Removing the copayment requirement for HIV medication would be cost-effective from a governmental perspective

The Potential for Zinc Stable Isotope Techniques and Modelling to Determine Optimal Zinc Supplementation

It is well recognised that zinc deficiency is a major global public health issue, particularly in young children in low-income countries with diarrhoea and environmental enteropathy. Zinc supplementation is regarded as a powerful tool to correct zinc deficiency as well as to treat a variety of physiologic and pathologic conditions. However, the dose and frequency of its use as well as the choice of zinc salt are not clearly defined regardless of whether it is used to treat a disease or correct a nutritional deficiency. We discuss the application of zinc stable isotope tracer techniques to assess zinc physiology, metabolism and homeostasis and how these can address knowledge gaps in zinc supplementation pharmacokinetics. This may help to resolve optimal dose, frequency, length of administration, timing of delivery to food intake and choice of zinc compound. It appears that long-term preventive supplementation can be administered much less frequently than daily but more research needs to be undertaken to better understand how best to intervene with zinc in children at risk of zinc deficiency. Stable isotope techniques, linked with saturation response and compartmental modelling, also have the potential to assist in the continued search for simple markers of zinc status in health, malnutrition and disease

Additional file 2: of The effect of dietary resistant starch type 2 on the microbiota and markers of gut inflammation in rural Malawi children

16S rRNA raw reads analyzed in this study

Additional file 1: Table S1. of The effect of dietary resistant starch type 2 on the microbiota and markers of gut inflammation in rural Malawi children

Number of 16S rRNA and wide genome sequences generated per sample. This table shows the number of raw (unprocessed) reads and the number of reads remaining after analytical processing of 18 samples from children fed with the habitual diet and plus the addition of RS. Table S2 Comparison of the number of reads obtained by V1–V3 and V3–V5 sequencing. Figure S1 Venn diagram showing the degree of overlap for genera captured with the V1–V3 and V3–V5 regions. While the majority of taxa are captured by both sets of primers, the fact that a significant subset were captured by only one primer set made the use of both sets more valuable. Figure S2 LEfse rank plot of differentially abundant genes in gut microbiomes initial samples vs. final samples. LDA scores were given for different abundance of genes before (habitual diet: green) and after the resistant starch was added to the habitual diet (habitual diet + RS: red). Figure S3 Principal component analysis (PCA) plot showing the differential clustering of metabolites in fecal samples collected before (blue-habitual diet) and after (red-habitual diet plus RS) the diet supplementation with RS. Brown circles represent replicate analyses of the pooled quality control (QC) fecal samples. The tight clustering of these QC replicate analyses indicates the high reproducibility and low amount of drift associated with the GC/MS-based fecal metabolomic profiling analyses conducted over several hours while the individual fecal extracts are analyzed at the same time, under identical GC/MS conditions, and on the same GC/MS instrument

Gay Community Periodic Survey: Adelaide 2009

The Adelaide Gay Community Periodic Survey is a cross-sectional survey of gay and homosexually active men recruited through a range of gay community sites in Adelaide. The project was funded by the Department of Human Services, South Australia. The Periodic Survey provides a snapshot of sexual and HIV-related practices among gay and homosexually active men