Stimulating health-promoting bacteria[edit]
Galacto-oligosaccharides have been shown to be an excellent source for health-promoting bacteria such as Bifidobacteria and Lactobacilli. Many studies with infants and adults have shown that foods or drinks enriched with galacto-oligosaccharides result in a significant increase in Bifidobacteria. In comparison with other oligosaccharides, a large bifidogenic effect was shown for galacto-oligosaccharides.[4][5][6][7][8][9][10][11] For example, an in vitro study showed that, in comparison to several carbohydrates, galacto-oligosaccharides were shown to support the most favourable growth characteristics for Bifidobacteria and Lactobacilli.[12] However, not all GOS result in the same effect due to differences in their structures as explained above. For example, it was shown that consumption of a galacto-oligosaccharide mixture produced with enzymes originating from bifidobacterial species resulted in an increase in the bifidogenic properties in comparison to a galacto-oligosaccharide mixture produced with another enzyme.[13]
Support of natural defenses[edit]
Human gut microbiota play a key role in the intestinal immune system, in maintaining a disease-free state. The gut and immune system form a complex structure that provides defense against ingested toxins and pathogenic bacteria. A well-balanced gut microflora is thought to play a particularly important role in the natural defense of the human body. Galactooligosaccharides support natural defenses of the human body via the gut microflora,[14] indirectly by increasing a number of good bacteria in the gut and inhibiting the binding or survival of Escherichia coli, Salmonella Typhimurium and Clostridia to the body, reducing the chances of getting infected.[15][16][17][18] Furthermore, GOS can positively influence the immune system—indirectly through the production of antimicrobial substances as the result of galactooligosaccharide fermentation, that can reduce the proliferation of pathogenic bacteria,[19][20] and directly by interaction with immune cells.[21][22][23][24] For example, in infants the usage of GOS has been shown to have a potential role in allergy prevention and reduction of infectious diseases.[25][26] GOS supplementation has also been shown to reduce symptoms of gastrointestinal dysfunction and reduce the number of days with cold or flu in stressed undergraduate students undergoing exams.[27]
Improvement of mineral absorption[edit]
While calcium is necessary for processes such as bone development, only part of the calcium present in the diet is available for absorption. GOS can contribute to the provision of sufficient levels of calcium as it stimulates its absorption. In humans it has been demonstrated that the consumption of GOS significantly increases calcium absorption.[28] In animal studies it has been demonstrated that administration of galacto-oligosaccharides results in more efficiently absorbed calcium and increased bone density, indicating the prevention of bone losses.[29][30] Not only calcium absorption is positively influenced, there are indications that the absorption of magnesium can be improved as well.[31]
Relief of constipation[edit]
Constipation is a frequent problem, particularly among infants, elderly and pregnant women. In infants, formula feeding is associated with constipation and hard stools.[32] For those suffering from constipation, consumption of galacto-oligosaccharides can offer relief to their constipation. It has been shown that galacto-oligosaccharides increase frequency of defecation, soften the stools and improve stool consistency.[33][34][35][36][37][38][39][40]
Synbiotic properties[edit]
GOS is a prebiotic. The main similarity between pre- and probiotics is that they both result in beneficial effects to the host after consumption. Combinations of pre- and probiotics with synergistic effects are often referred to as synbiotics. Clinical studies with infants and children indicated that addition of galacto-oligosaccharides to a probiotic mixture resulted in higher numbers of Bifidobacteria and increased resistance to respiratory infections during the first two years of life as compared to only the probiotic.[41][42] In this way, GOS can enhance the effect of a probiotic.
FODMAP and flatulence[edit]
Galacto-oligosaccharides are selectively fermented by colonic bacteria. All these bacteria produce gas at fermentation. The fermentatiion of galacto-oligosaccharides, mainly by bifidobacteria, produces the least volume of gas, compared to other prebiotic oligosaccharides.[43] They do not contribute to flatulence and gastrointestinal discomfort, when taken at the recommended dose. For this reason, they are not classed as FODMAPs and should not be restricted on the low-FODMAP diet, contrary to fructose, fructans and alpha-linked galactose-containing oligosaccharides such as those found in various legumes and beans. Excessive intake can, however, contribute to loss of specificity leading to fermentation by a number of other colonic bacteria that do produce more gas.