Efficacy of various dietary calcium salts to improve intestinal resistance to Salmonella infection in rats

Calcium-rich dairy matrix protects better than mineral calcium against colonic luminal haem-induced alterations in male rats

The haemoglobin content in meat is consistently associated with an increased risk of colorectal cancer, whereas calcium may play a role as a chemopreventive agent. Using rodent models, calcium salts have been shown to prevent the promotion of haem-induced and red meat-induced colorectal carcinogenesis by limiting the bioavailability of the gut luminal haem iron. Therefore, this study aimed to compare impacts of dietary calcium provided as calcium salts or dairy matrix on gut homoeostasis perturbations by high haeminic or non-haeminic iron intakes. A 3-week intervention study was conducted using Fischer 344 rats. Compared to the ferric citrate-enriched diet, the haemoglobin-enriched diet led to increased faecal, mucosal, and urinary lipoperoxidation-related biomarkers, resulting from higher gut luminal haem iron bioavailability. This redox imbalance was associated to a dysbiosis of faecal microbiota. The addition of calcium to haemoglobin-enriched diets limited haem iron bioavailability and counteracted redox imbalance, with improved preventive efficacy when calcium was provided in dairy matrix. Data integration revealed correlations between haem-induced lipoperoxidation products and bacterial communities belonging to Peptococcaceae, Eubacterium coprostanoligenes group, and Bifidobacteriaceae. This integrated approach provides evidence of the benefits of dairy matrix as a dietary calcium vehicle to counteract the deleterious side-effects of meat consumption.

Term infant formula supplemented with milk-derived oligosaccharides shifts the gut microbiota closer to that of human milk-fed infants and improves intestinal immune defense: a randomized controlled trial

BACKGROUND

Bovine milk-derived oligosaccharides (MOS) containing primarily galacto-oligosaccharides with inherent concentrations of sialylated oligosaccharides can be added to infant formula to enhance the oligosaccharide profile.

OBJECTIVE

To investigate the effects of an MOS-supplemented infant formula on gut microbiota and intestinal immunity.

METHODS

In a double-blind, randomized, controlled trial, healthy term formula-fed infants aged 21-26 d either received an intact protein cow milk-based formula (control group, CG, n = 112) or the same formula containing 7.2 g MOS/L (experimental group, EG, n = 114) until the age of 6 mo. Exclusively human milk-fed infants (HFI, n = 70) from an observational study served as the reference. Fecal samples collected at baseline, and the ages of 2.5 and 4 mo were assessed for microbiota (16S ribosomal RNA-based approaches), metabolites, and biomarkers of gut health and immune response.

RESULTS

Aged 2.5 and 4 mo, redundancy analysis (P = 0.002) and average phylogenetic distance (P < 0.05) showed that the overall microbiota composition in EG was different from CG and closer to that of HFI. Similarly, EG caesarean-born infants were different from CG caesarean- or vaginally born infants and approaching HFI vaginally born infants. Relative bifidobacteria abundance was higher in EG compared with CG (P < 0.05) approaching HFI. At the age of 4 mo, counts of Clostridioides difficile and Clostridium perfringens were ∼90% (P < 0.001) and ∼65% (P < 0.01) lower in EG compared with CG, respectively. Geometric LS mean (95% CI) fecal secretory IgA in EG was twice that of CG [70 (57, 85) compared with 34 (28, 42) mg/g, P < 0.001] and closer to HFI. Fecal oral polio vaccine-specific IgA was ∼50% higher in EG compared with CG (P = 0.065). Compared with CG, EG and HFI had lower fecal calcium excretion (by ∼30%, P < 0.005) and fecal pH (P < 0.001), and higher lactate concentration (P < 0.001).

CONCLUSIONS

Infant formula with MOS shifts the gut microbiota and metabolic signature closer to that of HFI, has a strong bifidogenic effect, reduces fecal pathogens, and improves the intestinal immune response.

A Marine-Derived, Multi-mineral Supplement Influences Bacterial Fermentation and Short Chain Fatty Acid Profile In Vitro

Aquamin is a calcium-rich multi-mineral supplement derived from the red marine algae, Lithothamnion species. Calcium supplementation has been shown to exert a prebiotic-like effect on the gut microbiota and has been associated with distinct changes in lactate and short chain fatty acid (SCFA) production. Irritable bowel syndrome (IBS) subtype is associated with changes in SCFA levels compared with healthy controls. Using an ex vivo simulation model, and a fecal inoculum from a patient diagnosed with IBS, we evaluated the effects of Aquamin (at 6 and 30 mg/mL) on SCFAs and lactate production, pH and gas production, and human microbiota composition. Our results demonstrate that Aquamin increased SCFA production (acetate and propionate by 8% and 24%, respectively, at 30 mg/mL dose), significantly decreased lactate production (30 mg/mL), and increased colonic fluid pH without inducing changes in colonic gas production or gastrointestinal (GI) microbiota composition. These results indicate that Aquamin may play a role in optimizing GI microbial function in an ex vivo setting.

Subclinical mastitis (SCM) and proinflammatory cytokines are associated with mineral and trace element concentrations in human breast milk

The possibility that either subclinical mastitis (SCM), an inflammatory condition of the breast, or elevations in breast milk proinflammatory cytokines alter breast milk mineral and trace element composition in humans has not been investigated. In this cross-sectional study, breast milk samples (n=108) were collected from Guatemalan Mam-Mayan mothers at one of three stages of lactation (transitional, early and established), and categorized as SCM (Na:K >0.6) or non-SCM (Na:K ≤0.6). Milk concentrations of 12 minerals (calcium, copper, iron, magnesium, manganese, phosphorus, potassium, rubidium, selenium, sodium, strontium, and zinc) and 4 proinflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) were measured by inductively coupled plasma mass spectrometry (ICP-MS), Lachat analyzer or Luminex multiplex bead cytokine assay. SCM was more prevalent during transitional (30%) than early (15.6%) and established (8.9%) lactation. Analysis of variance revealed that breast milk minerals differed by stage of lactation and SCM status. Breast milk minerals with the exception of magnesium were lower in established lactation, whereas SCM was associated with higher selenium and lower phosphorus. Regression models that controlled for lactation stage also confirmed that SCM was associated with lower milk phosphorus and higher milk selenium concentrations. Furthermore, cytokine concentrations were independently associated with several mineral concentrations: IL-1β with higher phosphorus and iron, IL-6 with higher calcium, magnesium, copper and manganese, IL-8 with higher calcium and zinc, and TNF-α with lower iron and manganese. We conclude that milk mineral and trace element concentrations are affected not only by the presence of SCM but also by proinflammatory cytokines in breast milk.

Could the beneficial effects of dietary calcium on obesity and diabetes control be mediated by changes in intestinal microbiota and integrity?

Evidence from animal and human studies has associated gut microbiota, increased translocation of lipopolysaccharide (LPS) and reduced intestinal integrity (II) with the inflammatory state that occurs in obesity and type 2 diabetes mellitus (T2DM). Consumption of Ca may favour body weight reduction and glycaemic control, but its influence on II and gut microbiota is not well understood. Considering the impact of metabolic diseases on public health and the role of Ca on the pathophysiology of these diseases, this review critically discusses possible mechanisms by which high-Ca diets could affect gut microbiota and II. Published studies from 1993 to 2015 about this topic were searched and selected from Medline/PubMed, Scielo and Lilacs databases. High-Ca diets seem to favour the growth of lactobacilli, maintain II (especially in the colon), reduce translocation of LPS and regulate tight-junction gene expression. We conclude that dietary Ca might interfere with gut microbiota and II modulations and it can partly explain the effect of Ca on obesity and T2DM control. However, further research is required to define the supplementation period, the dose and the type of Ca supplement (milk or salt) required for more effective results. As Ca interacts with other components of the diet, these interactions must also be considered in future studies. We believe that more complex mechanisms involving extraintestinal disorders (hormones, cytokines and other biomarkers) also need to be studied.

Dietary calcium concentration and cereals differentially affect mineral balance and tight junction proteins expression in jejunum of weaned pigs

Ca plays an essential role in bone development; however, little is known about its effect on intestinal gene expression in juvenile animals. In the present study, thirty-two weaned pigs (9·5 (SEM 0·11) kg) were assigned to four diets that differed in Ca concentration (adequate v. high) and cereal composition (wheat-barley v. maize) to assess the jejunal and colonic gene expression of nutrient transporters, tight junction proteins, cytokines and pathogen-associated molecular patterns, nutrient digestibility, Ca balance and serum acute-phase response. To estimate the impact of mucosal bacteria on colonic gene expression, Spearman's correlations between colonic gene expression and bacterial abundance were computed. Faecal Ca excretion indicated that more Ca was available along the intestinal tract of the pigs fed high Ca diets as compared to the pigs fed adequate Ca diets (P> 0.05). High Ca diets decreased jejunal zonula occludens 1 (ZO1) and occludin (OCLN) expression, up-regulated jejunal expression of toll-like receptor 2 (TLR2) and down-regulated colonic GLUT2 expression as compared to the adequate Ca diets (P< 0.05). Dietary cereal composition up-regulated jejunal TLR2 expression and interacted (P= 0.021) with dietary Ca on colonic IL1B expression; high Ca concentration up-regulated IL1B expression with wheat-barley diets and down-regulated it with maize diets. Spearman's correlations (r> 0·35; P< 0·05) indicated an association between operational taxonomic units assigned to the phyla Bacteroidetes, Firmicutes and Proteobacteria and bacterial metabolites and mucosal gene expression in the colon. The present results indicate that high Ca diets have the potential to modify the jejunal and colonic mucosal gene expression response which, in turn, interacts with the composition of the basal diet and mucosa-associated bacteria in weaned pigs.

The protective effect of supplemental calcium on colonic permeability depends on a calcium phosphate-induced increase in luminal buffering capacity

An increased intestinal permeability is associated with several diseases. Previously, we have shown that dietary Ca decreases colonic permeability in rats. This might be explained by a calcium-phosphate-induced increase in luminal buffering capacity, which protects against an acidic pH due to microbial fermentation. Therefore, we investigated whether dietary phosphate is a co-player in the effect of Ca on permeability. Rats were fed a humanised low-Ca diet, or a similar diet supplemented with Ca and containing either high, medium or low phosphate concentrations. Chromium-EDTA was added as an inert dietary intestinal permeability marker. After dietary adaptation, short-chain fructo-oligosaccharides (scFOS) were added to all diets to stimulate fermentation, acidify the colonic contents and induce an increase in permeability. Dietary Ca prevented the scFOS-induced increase in intestinal permeability in rats fed medium- and high-phosphate diets but not in those fed the low-phosphate diet. This was associated with higher faecal water cytotoxicity and higher caecal lactate levels in the latter group. Moreover, food intake and body weight during scFOS supplementation were adversely affected by the low-phosphate diet. Importantly, luminal buffering capacity was higher in rats fed the medium- and high-phosphate diets compared with those fed the low-phosphate diet. The protective effect of dietary Ca on intestinal permeability is impaired if dietary phosphate is low. This is associated with a calcium phosphate-induced increase in luminal buffering capacity. Dragging phosphate into the colon and thereby increasing the colonic phosphate concentration is at least part of the mechanism behind the protective effect of Ca on intestinal permeability.