A daily 5 gram dose of the GOS prebiotic fiber was found to alter the gut microflora, which led to an increase in the absorption of calcium, according to findings published in the British Journal of Nutrition.
Commenting independently on the study, Prof Glenn Gibson, a world-renowned prebiotic expert at the University of Reading, told us: “This looks at a plausible health-related output associated with prebiotics. Most prior work has been done in this regard with fructans, but galactans are also efficacious prebiotics.
“The study shows the expected changes in gut microbiota composition, but tallies this with improved calcium absorption. There are obvious implications for bone health and the study population chosen has relevance in this regard.
“The Purdue researchers are leading experts in this area of research.”
The new study follows an earlier animal study from the same researchers, and used GOS derived from the dairy sugar lactose. The study used FrieslandCampina’s Vivinal GOS-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. Calcium is 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% 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.
Researchers from Purdue University and FrieslandCampina recruited 31 healthy adolescent girls between the ages of 10 and 13, and randomly assigned them to consume smoothie drinks with 0, 2·5 or 5 g GOS two times per day for three 3-week periods.
Results showed that the prebiotic smoothies increased calcium absorption, but the increase was not linked to the level of the GOS dose, with significant improvements observed in both low and high dose groups.
Changes in the gut microflora were also observed, with bifidobacteria increasing significantly in the 5 gram group, compared with the control or 10 gram groups.
“The response to GOS in fractional Ca absorption occurred as late phase absorption between 24 and 36 h, characteristic of lower gut absorption,” explained the researchers, led by Purdue’s Connie Weaver.
“Supplementation with 5 g/d of GOS improved Ca absorption and may increase peak bone mass accrual during adolescence by influencing microbial communities in the lower gut,” they concluded.
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.
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S000711451300055X
“Galacto-oligosaccharides increase calcium absorption and gut bifidobacteria in young girls: a double-blind cross-over trial”
Authors: C.M. Whisner, B.R. Martin, M.H.C. Schoterman, C.H. Nakatsu, L.D. McCabe, G.P. McCabe, M.E. Wastney, E.G.H.M. van den Heuvel, C.M. Weaver