Galacto-oligosaccharides are bifidogenic and safe at weaning: a double-blind randomized multicenter study.

OBJECTIVES: The primary objective of this study was to determine the bifidogenic effect of galacto-oligosaccharides (GOS) in a follow-on formula and the effects on other intestinal bacteria. Secondary objectives were the effects on stool characteristics, growth, and general well-being. PARTICIPANTS AND METHODS: In a multicenter, double-blind study, 159 healthy infants, formula-fed at enrollment (at 4-6 months), were randomized to an experimental follow-on formula supplemented with 5 g/L (GOS) (77 infants), or to a standard follow-on formula (control, 82 infants). Infants were evaluated at enrollment (study day 1 = sd1), after 6 weeks (study day 2 = sd2), and after an additional 12 weeks (study day 3 = sd3). At each study day, a fresh stool sample for the bacterial counts was collected, and the growth parameters were measured. At sd2, urinary specimens were collected for the evaluation of urinary osmolarity. RESULTS: At sd2 and sd3, the GOS group had a higher median number (colony-forming units per gram of stool) of bifidobacteria than did the control group (sd2 GOS 9.2 x 10(9) vs control 4.4 x 10(9), P = 0.012); (sd3 GOS 7.2 x 10(9) vs control 2.4 x 10(9), P = 0.027). Other bacteria did not show any significant differences between the 2 groups at all study days. The GOS produced softer stools but had no effect on stool frequency. The urinary osmolarity (mOsm/L) at sd2 was comparable in both groups. Supplementation had no influence on the incidence of gastrointestinal side effects or on the growth of the infants. CONCLUSIONS: These data indicate that the addition of GOS (5 g/L) to a follow-on formula positively influences the bifidobacteria flora and the stool consistency in infants during the supplementation period at weaning. No local or systemic side effects were recorded.

Prostaglandin E synthase 2 (PTGES2) Arg298His polymorphism and parameters of the metabolic syndrome.

The prostaglandin E synthase 2 (PTGES2) gene maps to a locus linked to obesity and is involved in the synthesis of the antilipolytic compound prostaglandin E(2). In a recent study, we found an association of the minor PTGES2 Arg298His allele and lower risk of type 2 diabetes mellitus in the European Investigation into Cancer and Nutrition (EPIC) and Cooperative Health Research in the Augsburg Region (KORA) cohorts. Here, we employed our Metabolic Intervention Cohort Kiel (MICK) to assess the influence of the PTGES2 Arg298His polymorphism on a wider scale of parameters of the metabolic syndrome and postprandial metabolism. In comparison to subjects homozygous for the Arg allele, carriers of the His-allele showed significantly lower fasting insulin (geometric mean +/- SEM: 11.8 muU/mL, 11.41-12.25 versus 13.0, 12.71-13.33; p = 0.023), lower postprandial insulin levels after an oral glucose tolerance test (area under the curve 77.2, 74.07-80.52 versus 81.2, 78.8-83.63; p = 0.023) and lower homeostasis model assessment (HOMA)-insulin-resistance (3.030, 2.909-3.157 versus 3.346, 3.257-3.438; p = 0.041) and HOMA-beta-cell-function (107.2, 104.04-110.52 versus 117.2, 114.65-119.71; p = 0.019). Adjustment for body mass index (BMI) resulted in a loss of these significant differences. BMI tended to show lower values in His-allele carriers, (p = 0.067). In conclusion, risk-reducing effects of the minor His allele of the PTGES2 Arg298His polymorphism could be mediated partly by lowered BMI.

Prebiotics, probiotics, and synbiotics affect mineral absorption, bone mineral content, and bone structure.

Several studies in animals and humans have shown positive effects of nondigestible oligosaccharides (NDO) on mineral absorption and metabolism and bone composition and architecture. These include inulin, oligofructose, fructooligosaccharides, galactooligosaccharides, soybean oligosaccharide, and also resistant starches, sugar alcohols, and difructose anhydride. A positive outcome of dietary prebiotics is promoted by a high dietary calcium content up to a threshold level and an optimum amount and composition of supplemented prebiotics. There might be an optimum composition of fructooligosaccharides with different chain lengths (synergy products). The efficacy of dietary prebiotics depends on chronological age, physiological age, menopausal status, and calcium absorption capacity. There is evidence for an independent probiotic effect on facilitating mineral absorption. Synbiotics, i.e., a combination of probiotics and prebiotics, can induce additional effects. Whether a low content of habitual NDO would augment the effect of dietary prebiotics or synbiotics remains to be studied. The underlying mechanisms are manifold: increased solubility of minerals because of increased bacterial production of short-chain fatty acids, which is promoted by the greater supply of substrate; an enlargement of the absorption surface by promoting proliferation of enterocytes mediated by bacterial fermentation products, predominantly lactate and butyrate; increased expression of calcium-binding proteins; improvement of gut health; degradation of mineral complexing phytic acid; release of bone-modulating factors such as phytoestrogens from foods; stabilization of the intestinal flora and ecology, also in the presence of antibiotics; stabilization of the intestinal mucus; and impact of modulating growth factors such as polyamines. In conclusion, prebiotics are the most promising but also best investigated substances with respect to a bone-health-promoting potential, compared with probiotics and synbiotics. The results are more prominent in animal models, where more studies have been performed, than in human studies, where experimental conditions are more difficult to control.