Galacto-oligosaccharides (GOS) belong to the group prebiotics. Prebiotics are defined as non-digestible food ingredients that beneficially affect the host by stimulating the growth and/or activity of beneficial bacteria in the colon. GOS benefits the bowel function by stimulating the growth and activity of the beneficial bacteria in the colon. It can help to increase defecation frequency and hence it can help to prevent constipation in the children and infants. Recent studies have shown that the administration of galacto-oligosaccharides results in more efficiently absorbed calcium and increased bone density, indicating the prevention of bone losses. Not only calcium absorption is positively influenced, there are indications that the absorption of magnesium can be improved as well.