Prebiotic Type Spotlight: Galactooligosaccharides (GOS)

Last updated March 2023

Each edition of GPA’s Prebiotic Spotlight focuses on a specific prebiotic type to raise awareness around the prebiotic itself, its sources, any notable and/or recent research, and how it is used in the marketplace. In this issue, galactooligosaccharides (GOS) are highlighted.

GOS has been recognized as a prebiotic for over two decades as its prebiotic activity has been extensively demonstrated in in vitro and in vivo animal and human studies.

GOS is composed of linear and branched oligosaccharides with two to eight degrees of polymerization (Wang et al., 2023). It is an indigestible food component that passes through the stomach and small intestine intact to reach the colon where it gets fermented by the gut microbiota. GOS further modulates the gut microbiota, increasing the abundance and enhancing the functionality of beneficial bacteria and conferring health benefits beyond the gut to various bodily systems (Azcarate-Peril et al., 2021; Mei et al., 2022; Wang et al., 2023).

Benefit Areas
GOS’ various prebiotic effects on human health have been explored throughout the years, which include:

  • Relief of gastrointestinal symptoms such as flatulence, bloating, and abdominal pain (Vulevic et al., 2018).
  • Positively affecting the aging gut by reducing intestinal permeability and increasing the mucus layer (Arnold et al., 2021).
  • Supporting healthy microbiome development in infants (Mei et al., 2022).
  • Reducing and alleviating skin conditions such as eczema (Moro et al., 2006; Wang et al., 2023).
  • Alleviating neurological diseases through the gut-brain axis (Wang et al., 2023).
  • Modulating the immune response and supporting healthy immune function (Vulevic et al., 2015; Williams et al., 2016).

GOS is naturally available in dairy products, legumes, and root vegetables. It is in either the α- or β-form, depending on the galactosidic bonds attached (Mei et al., 2022). α-GOS can be found in several plants such as soybeans, but its prebiotic effects are not as well-defined as β-GOS, which is widely used in research and commercial production (Mei et al., 2022; Mitmesser & Combs, 2017). GOS manufacturing methods include natural extraction, polysaccharide hydrolysis, chemical synthesis, and enzymatic synthesis. Currently, enzymatic conversion of lactose using β-galactosidases from bacteria, yeast, and filamentous fungi is the main method to produce GOS that is safe, effective, and does not cause environmental pollution (Maráz et al., 2022; Mei et al., 2022).

Dose Range
GOS is available in powder and syrup formats, with an oral daily dose of around 5 g typically required to confer a health benefit (ISAPP, 2020), whereas up to 16.2 g/day is generally considered safe (EFSA, 2021). Most studies utilize a daily dose of GOS between 5 g and 20 g (Azcarate-Peril et al., 2021; Wang et al., 2023), depending on the studied age group (adults vs infants) and the GOS formulation (fortified food or formula vs supplements). Nonetheless, proprietary formulations of GOS that have specific structures are showing efficacy at lower amounts, eliciting a prebiotic effect at only 1.37 g per day (Huaman et al., 2018; Vulevic et al., 2018; Wilson et al., 2020).

Recent Research
GOS continues to be widely studied. Fifteen trials are currently recruiting participants to use GOS, either alone, as part of a synbiotic mixture, or in a multi-ingredient product, for conditions including microbial colonization, acute graft-versus-host disease (GVHD), iron-deficiency in HIV-infected children, respiratory infection, pre-diabetes, pediatric obesity, irritable bowel syndrome (IBS), Crohn’s disease, anxiety, stress, sleep, aging, and polycystic ovary syndrome (PCOS) (, 2023). Meanwhile, searching “galactooligosaccharides” in PubMed retrieved 32 articles published just this year. The studies analyzed various conditions such as gestational diabetes mellitus, colitis, respiratory infections, and others (PubMed, 2023).

Wan et al. (2023) investigated the effects of GOS in pregnancy, including changes in the maternal gut microbiota, lipid metabolism, glucose metabolism, and inflammatory markers. This study reported that GOS could be safely used as a dietary supplement during pregnancy. Turati et al. (2023) evaluated the association between the intake of foods rich in prebiotic fibers such as inulin-type fructans (ITFs) and multiple types of fructooligosaccharides (FOS) and GOS on colorectal cancer risk. Their results showed that colorectal cancer risk was inversely associated with dietary GOS intake, but not ITFs or FOS. Moreover, multiple studies are also exploring the use of GOS in synbiotic formulations for supporting healthy infant microbiome development and potentially alleviating the risk of respiratory infections (Lagkouvardos et al., 2023; Sjödin et al., 2023).

How is GOS used in the marketplace?
GOS is used as a prebiotic ingredient in various food and pharmaceutical formulations, either as a standalone ingredient or combined with other prebiotics. In infant nutrition, GOS is one of the preferred prebiotics in supplementing infant formulas, mimicking the beneficial effects of the human milk oligosaccharides naturally found in breast milk (Arnold et al., 2021).

GOS has excellent technological properties such as high solubility, low viscosity, stable across a wide range of pH and temperatures, and a pleasant texture with a sweet flavor (Maráz et al., 2022). Due to these factors, GOS is used as a functional food additive, improving food’s physicochemical, optical, and sensory characteristics, and exerting beneficial health effects (Wang et al., 2023). It is added to functional foods such as dairy products, snacks, nutrition bars, and beverages, in addition to feedstock, pharmaceuticals, dietary supplements, and cosmetics (Maráz et al., 2022).             

The global market size for GOS was estimated at USD 570 million in 2022 and is expected to reach a value of USD 850 million by 2028 (Market Data Forecast, 2022).

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