You may have heard a lot about galactooligosaccharides (GOS) recently and wondered what they are?

GOS prebiotics are derived from the lactose in cow’s milk. They are a type of fibre which feed good bacteria in your large intestine. GOS has an advantage over other types of prebiotics, (e.g. inulin, oligofructose, fructooligosaccharides (FOS)) as it can give a prebiotic effect at a low dose*.   

Higher doses of prebiotics may increase gas production in some people, so nourishing your good bacteria at the lowest dose can be important.

How does GOS work?

GOS is a fermentable fibre and is not digested until it reaches your large intestine.  Once there it is consumed by ‘friendly’ bacteria, in particular Bifidobacteria and Lactobacilli, increasing their numbers and improving the balance and diversity of your gut microbiota. 

Studies on Bimuno® (a leading GOS supplement), have shown that this will start to happen after 2-3 days. 

Why should I take a GOS supplement?

Bifidobacteria is an important bacteria which contributes to many essential processes in your body, including digestion, immunity and cognition, and its numbers in the gut naturally decrease as we age. As ‘friendly’ bacteria thrive, there is less room in the gut for ‘harmful’ bacteria to take hold.

In addition to out-competing harmful bacteria, research shows GOS interacts with other mechanisms in the gut to deliver additional benefits such as increasing calcium absorption and the production of vitamin B12 and K.

How are GOS supplements made?

Commercially available GOS, like Bimuno, is manufactured by adding an enzyme to lactose** in controlled conditions, which ensures that it offers a consistent prebiotic effect in every dose. Different GOS supplements are produced from different enzymes and therefore the effects may vary.

GOS as a source of fibre

According to a National Diet and Nutrition survey conducted by Public Health England, only 4% of women and 9% of men achieve the recommended daily intake of fibre***. The GOS supplement Bimuno contributes 2g (40%) of our 5g recommended daily fermentable fibre intake.  This will help you support the levels of good bacteria in your gut and help achieve the daily target 30g of fibre as part of a healthy, balanced diet.

Prebiotics in food

Prebiotics including GOS and FOS can be found naturally in fruit and vegetables such as:

  • Legumes (e.g. red kidney beans, chickpeas, baked beans, split peas, lentils)
  • Hummus dip
  • Cashews and pistachios
  • Soy milk made from whole soy beans
  • Drinks made with soy milk containing GOS e.g. soy cappuccino
  • Oat milk
  • Freekeh


*Clinical studies show that Bimuno, a leading GOS supplement, has an effect at a daily dose of 2.8g.  

**The lactose value in Bimuno is under the EFSA threshold for intolerance of 12g/single dose

***National Diet and Nutrition Survey