Led by researchers from Purdue University, the researchers report that inclusion of between 2 and 6 percent of galactooligosaccharides (GOS) increased both the utilization of calcium and magnesium and also the bone properties in growing rats.
“The ability for each percent increase in dietary GOS to enhance calcium absorption by almost 1.7 percent and that of magnesium by almost 3 percent is an important contribution of this functional food ingredient,” wrote the researchers in the Journal of Agricultural and Food Chemistry.
GOS are derived from the dairy sugar lactose. The study used FrieslandCampina’s Vivinal GOS90-branded ingredient and the Dutch dairy giant funded the study.
Fibers and bones
The study adds to an every growing body of science supporting the potential bone health benefits of prebiotic fiber intake. The fibers are reported to help bone strength by changing the flora in the colon.
The fiber selectively promotes the growth of beneficial bacteria in the gut, which in turn produce short chain fatty acids. These fatty acids decrease the pH within the intestine, and improve the solubility of the minerals present. The calcium and magnesium are then better absorbed into the body.
Maximizing the build-up of bone during the highly important pubescent years is seen as one of the two best ways to reduce the risk of osteoporosis later in life. About 35 per cent of a mature adult's peak bone mass is built-up during puberty.
The other approach is to boost bone density in high-risk post-menopausal women by improved diet or supplements.
Osteoporosis is characterized by low bone mass, which leads to an increase risk of fractures, especially the hips, spine and wrists. An estimated 75 million people suffer from osteoporosis in Europe, the USA and Japan.
Women are four times more likely to develop osteoporosis than men.
Led by Connie Weaver, PhD, distinguished professor and head of the Department of Foods and Nutrition at Purdue University, the researchers investigated the effect of different doses of GOS on mineral absorption and bone health in growing rats.
Animals had their normal diet supplemented with 0, 2, 4, 6, or 8 percent GOS for eight weeks.
Results showed that the GOS was associated with a decrease in pH in the upper part of the large intestine (the cecum), a result that appears consistent with the proposed mechanism of action of prebiotics. Bifidobacteria concentrations in the gut also increased.
The researchers also found that, as the dose of the prebiotic increased, the absorption of calcium increased. Magnesium absorption also increased in response to prebiotic supplementation, but this was not related to the dose provided.
Bone density analysis revealed that the GOS supplements produced increases at a range of skeletal sites, including the thigh and the shin bone.
“Two percent GOS in a rat’s diet by weight corresponds to almost 8 g of GOS/day in a human if determined on the basis of proportional body surface area,” explained Prof Weaver and her co-workers.
“Fiber intake recommendations for children are 14 g/1000 kcal, but most children consume well below the recommended levels. Addition of a prebiotic to foods popular with children is a strategy to improve fiber consumption.
“On the basis of the results of this study, GOS seem to have potential to contribute to improved peak bone mass and strength,” they concluded.
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print, Article ASAP, doi: 10.1021/jf2009777
"Galactooligosaccharides Improve Mineral Absorption and Bone Properties in Growing Rats through Gut Fermentation"
Authors: C.M. Weaver, B.R. Martin, C.H. Nakatsu, A.P. Armstrong, A. Clavijo, L.D. McCabe, et al.