Prebiotic to Improve Calcium Absorption in Postmenopausal Women After Gastric Bypass: A Randomized Controlled Trial

Context The adverse skeletal effects of Roux-en-Y gastric bypass (RYGB) are partly caused by intestinal calcium absorption decline. Prebiotics, such as soluble corn fiber (SCF), augment colonic calcium absorption in healthy individuals. Objective We tested the effects of SCF on fractional calcium absorption (FCA), biochemical parameters, and the fecal microbiome in a post-RYGB population. Design, Setting, Participants : Randomized, double-blind, placebo-controlled trial of 20 postmenopausal women with history of RYGB mean 5 years prior. Intervention 2-month course of 20 g/day SCF or maltodextrin placebo orally. Main Outcomes Between-group difference in absolute change in FCA (primary outcome) was measured with a gold-standard dual stable isotope method. Other measures included tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing. Results Mean FCA ±SD at baseline was low at 5.5±5.1%. Comparing SCF to placebo, there was no between-group difference in mean (95% CI) change in FCA (+3.4 [-6.7,+13.6]%), nor in calciotropic hormones or bone turnover markers. The SCF group had a wider variation in FCA change than placebo (SD 13.4% vs. 7.0%). Those with greater change in microbial composition following SCF treatment had greater increase in FCA (r 2=0.72,p=0.05). SCF adherence was high, and GI symptoms similar between groups. Conclusions No between-group differences were observed in changes in FCA or calciotropic hormones, but wide confidence intervals suggest a variable impact of SCF that may be due to the degree of gut microbiome alteration. Daily SCF consumption was well-tolerated. Larger and longer-term studies are warranted.

Conversion of corn fiber into fuel ethanol

Corn fiber due to its chemical composition (up to 20% starch, 50 - 60% non-starch polysaccharides) and availability has potential to serve as a substrate for manufacture of various products, including fuel ethanol. This paper deals with assessment of fiber-to-ethanol conversion. The water/dry fiber ratio in suspensions was 10/1. Enzyme liquefaction and saccharification of residual starch in corn fiber was carried out in two steps with thermostable α-amylase (20 min, 120°C) and mixture of pullulanase and glucomalyse (24 hours, 60°C). Procedures resulted in release of 57.7±1.6 mg of glucose per gram of dry fiber basis. It responds to the dextrose equivalent expression to 96.7±2.2%. By fermentation of the starch hydrolysates by yeasts Saccharomyces cerevisiae CCY-11-3 (5% v/v inoculum, 28°C, 72 hours) 0.48 g of ethanol per gram of glucose in hydrolysates was obtained. The solids after starch hydrolysis were separated by filtration and processed by acid pretreatment (0.1 g of conc. HCl/g of biomass/5 ml of water, 120°C, 20 min) with subsequent enzyme hydrolysis (24 hours, 60°C) by the multienzyme preparations containing cellulases and hemicellulases. Overall yield of reducing sugars after these two steps was 740.7±3.9 mg/gram of dry corn fiber basis. Fermentation of lignocellulosic hydrolysates by yeasts Pichia stipitis CCY-39-50-1 and Candida shehatea CCY-29-68-4 (in both cases 5% v/v inoculum, 28°C, 72 hours) resulted in 0.38 and 0.12 g of ethanol per gram of reducing sugars. The results indicate that applied pretreatment methods and used microorganisms are able to produce ethanol from corn fiber.

Prospects of Maize (Corn) Wet Milling By-Products as a Source of Functional Food Ingredients and Nutraceuticals

Maize (corn) consists of distinct parts, germ, endosperm, and pericarp, with different chemical compositions. During the maize wet milling process, the maize is disintegrated into the main product starch and by-products, including corn germ, corn fiber and corn gluten (the technical term for corn endosperm specific proteins and not the same as wheat gluten). These by-products are used as low-value animal feed products. The corn germ contains high amounts of tocols and phospholipids, while the corn gluten is rich in carotenoids and the corn fiber fraction is rich in phytosterols and complex carbohydrates. Each by-product has the potential to serve as a precursor in the manufacture of functional food ingredients or nutraceuticals that have antioxidant, anti-inflammatory, hypocholesterolemic, hypolipidemic and hypoglycemic properties. These food ingredients/nutraceuticals can be obtained through physical, chemical or enzymatic processes. Some nutraceuticals and food ingredients with market potential include corn fiber gum, oil, arabinoxylans, and xylo-oligosaccharides from corn fiber; corn germ oil and phospholipid ester from corn germ; and carotenoids and oligopeptides from corn gluten. This review focuses on current and prospective research into the use of corn germ, corn fiber and corn gluten in the production of potentially high-quality food ingredients or nutraceuticals.

Therapeutic Potential of Various Plant-Based Fibers to Improve Energy Homeostasis via the Gut Microbiota

Obesity is due in part to increased consumption of a Western diet that is low in dietary fiber. Conversely, an increase in fiber supplementation to a diet can have various beneficial effects on metabolic homeostasis including weight loss and reduced adiposity. Fibers are extremely diverse in source and composition, such as high-amylose maize, β-glucan, wheat fiber, pectin, inulin-type fructans, and soluble corn fiber. Despite the heterogeneity of dietary fiber, most have been shown to play a role in alleviating obesity-related health issues, mainly by targeting and utilizing the properties of the gut microbiome. Reductions in body weight, adiposity, food intake, and markers of inflammation have all been reported with the consumption of various fibers, making them a promising treatment option for the obesity epidemic. This review will highlight the current findings on different plant-based fibers as a therapeutic dietary supplement to improve energy homeostasis via mechanisms of gut microbiota.