Galactooligosaccharide (GOS) Supplementation and Calcium Absorption in Girls (Friesland)

The Effect of Galactooligosaccharide (GOS) Supplementation on Calcium Absorption and Retention in Female Adolescent Girls

The purpose of this study is to determine the effects of galactooligosaccharide (GOS) supplementation on calcium absorption and and gut microbe profiles.

Galactooligosaccharides (GOS) have been shown to have positive effects on calcium absorption in animals and postmenopausal women. This study aims to see whether the addition of fiber in the form of GOS to a calcium-containing yogurt drink will increase calcium absorption compared to placebo in a group of girls near menarche. Secondary outcomes are to assess physical fitness and determine the relationship between physical fitness and calcium absorption in adolescent girls as well as assess changes in gut microbiota. During this three phase, randomized, controlled crossover study, participants will consume yogurt drinks supplemented with 0, 2.5 or 5 grams of GOS twice daily for three weeks. Following each three week period, participants will complete a weekend clinical visit to measure calcium absorption. Height, weight, bone density and geometry, calcium absorption, gut microbiota and physical fitness will be measured. Effects of this GOS fiber intervention may help elucidate a mechanism of action for improving bone health with fiber supplementation.

5 g galactooligosaccharide provided in two calcium-containing yogurt beverage (2.5 g in each drink) per day

10 g galactooligosaccharide added to two calcium-containing yogurt beverage (5 g in each drink) per day

Zero, 5 or 10 g/day of galactooligosaccharide will be administered in two yogurt drinks containing about 300 mg total calcium each per day for three weeks. During a clinical visit following three weeks of consumption, zero, 2.5 or 5 g of galactooligosaccharide will be administered in the same yogurt with the addition of 15 mg Ca-44 (calcium chloride). Participants will be given one of the above yogurts at breakfast in addition to intravenously receiving 3.5 mg Ca-43 (calcium chloride) in 4 ml saline one hour after breakfast consumption.

Calcium absorption will be measured using dual isotope methods. Calcium-44(Ca-44) as calcium chloride will be administered in a yogurt drink provided at breakfast along with a roll, butter, jam and juice. A second isotope, Calcium-43 (Ca-43) as calcium chloride will be administered intravenously, one hour after consumption of breakfast. Urine and blood samples will be collected over a period of 48 hours and levels of Ca-44 and Ca-43 will be measured in urine and blood. Levels of Ca-44 and Ca-43 will be expressed as a ratio (Ca-44/Ca-43).

Inclusion Criteria: Female between ages of 10 and 12 Calcium intake of 900-1300 mg/d Exclusion Criteria: Take medication that influences calcium metabolism Any disorder of calcium or bone homeostasis BMI>90th percentile for age Smoking, illegal drug consumption Any gastrointestinal disease (crohn's disease, celiac disease, inflammatory bowel disease) Any disease affecting kidney function Broken bone within last 6 months Dislike of yogurt or yogurt drinks Regular use of foods containing probiotics or prebiotics