Prebiotics and Bone Health

A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents.

Abrams SA, Griffin IJ, Hawthorne KM, Liang L, Gunn SK, Darlington G, Ellis KJ.US Department of Agriculture/Agricultural Research Service, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children’s Hospital, Houston, TX.

• Calcium absorption was measured with the use of stable isotopes at baseline and 8 wk and 1 year after supplementation.
• After 1 year the fructan group had a greater increment in both whole-body bone mineral content (difference: 35 +/- 16 g; P = 0.03) and whole-body bone mineral density (difference: 0.015 +/- 0.004 g/cm(2); P = 0.01) than did the control group.
• Daily consumption of a combination of prebiotic short- and long-chain inulin-type fructans significantly increases calcium absorption and enhances bone mineralization.

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

Scholz-Ahrens KE, Ade P, Marten B, Weber P, Timm W, Açil Y, Glüer CC, Schrezenmeir J. Institute of Physiology and Biochemistry of Nutrition, Federal Research Centre for Nutrition and Food-Location Kiel, D-24103 Kiel, Germany.

• Several studies in animals and humans have shown positive effects of nondigestible oligosaccharides (NDO) on mineral absorption and metabolism and bone composition and architecture.
• 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 and also best investigated substances with respect to a bone-health-promoting potential, compared with probiotics and synbiotics.

Effects of prebiotics on mineral metabolism.

Scholz-Ahrens KE, Schaafsma G, van den Heuvel ET, Schrezenmeier, J: Institute of Physiology and Biochemistry of Nutrition, Federal Dairy Research Center, Kiel, Germany.

• Nondigestible oligosaccharides (NDOs) have been found to stimulate absorption of several minerals and to improve mineralization of bone.
• This stimulatory effect of some NDOs is assumed to be mainly due to their prebiotic character.

Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women.

Holloway L, Moynihan S, Abrams SA, Kent K, Hsu AR, Friedlander AL. Clinical Studies Unit and Geriatric Research Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, California, USA.

• The purpose of the present investigation was to test the hypothesis that treatment with Oligofructose-enriched Inulin (OEI) would increase the absorption of both Ca and Mg and alter markers of bone turnover.
• Fifteen postmenopausal women (72.2 (SD 6.4) years) were treated with OEI or placebo for 6 weeks using a double-blind, placebo-controlled, cross-over design.
• Fractional absorption of Ca and Mg increased following OEI compared with placebo (P < 0.05). Bone resorption (by urinary deoxypyridinoline cross-links) was greater than baseline at 6 weeks of active treatment (P < 0.05).
• Bone formation (by serum osteocalcin) showed an upward trend at 3 weeks and an increase following 6 weeks of OEI (P < 0.05).
• These results suggest that 6 weeks of OEI can improve mineral absorption and impact markers of bone turnover in postmenopausal women. Further research is needed to determine why a greater response was found in women with lower initial spine bone mineral density.

Inulin and Oligofructose and Mineral Metabolism: The Evidence from Animal Trials.

Katharina E. Scholz-Ahrens, Jürgen Schrezenmeir ; J Nutr. 2007; 137: 2513S

• Nondigestible oligosaccharides have been shown to increase the absorption of several minerals (calcium, magnesium, in some cases phosphorus) and trace elements (mainly copper, iron, zinc).
• Inulin-type fructans including oligofructose and fructooligosaccharides are the best investigated food ingredients in this respect.
• Even a small stimulation of calcium absorption increased the mineral accumulation in the skeleton because of its persisting effect over months.
• Direct comparison of different inulin-type fructans revealed a more pronounced effect by inulin or a mixture of long-chain inulin and oligofructose than by oligofructose alone.
• Under certain conditions, inulin-type fructans may improve mineral absorption by their impact on the amelioration of gut health including stabilization of the intestinal flora and reduction of inflammation.
• The abundance of reports indicate that inulin-type fructans are promising substances that could help to improve the supply with available calcium in human nutrition and by this contribute to bone health.

Current data with inulin-type fructans and calcium, targeting bone health in adults.

Coxam V; J Nutr. 2007; 137(11 Suppl): P-2527S

• In humans, there is increasing evidence that the colon can absorb nutritionally significant amounts of calcium, and this process may be susceptible to dietary manipulation by fermentable substrates, especially inulin-type fructans.
• Inulin-type fructans can modulate calcium absorption because they are resistant to hydrolysis by mammalian enzymes and are fermented in the large intestine to produce short-chain fatty acids, which in turn reduce luminal pH and modify calcium speciation, and hence solubility, or exert a direct effect on the mucosal transport pathway.
• Quite a few intervention studies showed an improvement of calcium absorption in adolescents or young adults by inulin-type fructans.
• In the same way, a positive effect has been reported in older women.

Prebiotics and calcium bioavailability.

Cashman K. Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland. k.cashman@ucc.ie

• A prebiotic substance has been defined as a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon.
• Therefore, compared to probiotics, which introduce exogenous bacteria into the colonic microflora, a prebiotic aims at stimulating the growth of one or a limited number of the potentially health-promoting indigenous micro-organisms, thus modulating the composition of the natural ecosystem.
• In recent years, increasing attention has been focused on the possible beneficial effects of prebiotics, such as enhanced resistance to invading pathogens, improved bowel function, anti-colon cancer properties, lipid lowering action, improved calcium bioavailability, amongst others.