Enzyme therapy can help reduce symptoms in IBS patients sensitive to galacto-oligosaccharides (GOS)

Enzyme supplement

Dr Jane Varney & Dr Caroline Tuck - Research Dietitians, 16 November 2017

Our team at Monash University are excited to be able to share with you results from one of our latest studies, recently published in the American Journal of Gastroenterology. The results are especially important for vegetarians and vegans following a low FODMAP diet. 

The study measured whether an oral enzyme supplement 'alpha-galactosidase' could help people with IBS to better tolerate galacto-oligosaccharide (GOS) containing foods. 


Thirty one people with IBS were randomised to the order in which they completed a series of 3-day ‘test periods’. During each test period, they took either a full-dose, half-dose or placebo (dummy) enzyme treatment. Prior to each test period they were instructed to follow a diet low in FODMAPs and fibre for 3 days. During each test period they consumed a diet provided by the researchers that was low in all FODMAPs except GOS. Between each test period they ‘washed-out’ for up to 2 weeks to avoid what is called a ‘carry-over effect’. 

The study revealed a number of interesting findings: 

Firstly, it showed that the addition of GOS to a diet that was low in other FODMAPs induced symptoms in approximately 2/3 of participants. This suggests that approximately 1/3 of people with IBS are not GOS-sensitive. This is an interesting finding in itself and highlights the importance of establishing your individual level of FODMAP tolerance. 

Secondly, it showed that the full-dose enzyme treatment improved IBS symptoms in GOS-sensitive individuals. This effect was not observed with the half-dose or placebo treatment, suggesting that a sufficient dose of enzyme supplementation (300 GALU) is needed to achieve tolerance of GOS containing foods.

Although not specifically measured in this study, the timing of enzyme treatment may be important in determining efficacy. In this study, participants were instructed to take ½ the enzyme treatment immediately before their meal (of GOS containing foods) and half during the meal. Timing the enzyme treatment in this way may ensure that the enzyme has sufficient access to GOS that enters the gut. Similar advice regarding the timing of enzyme treatment is given to people taking oral enzyme treatments for other conditions, such as lactase for lactose intolerance and pancreatic enzymes for pancreatic enzyme insufficiency. 

This study did not reveal the ‘mechanism of action’, that is the means by which the enzyme exerted its effects, and while a number of theories were proposed, more work is needed to better understand these mechanisms. 

So what do these results mean for the use of the enzyme in practice?

Who should use it: The enzyme is only useful in patients with IBS. The results from our study showed that the enzyme worked best in ‘GOS-sensitive’ individuals. So if you have re-challenged FODMAPs and found that you react to high GOS foods such as legumes/pulses, then you may find this enzyme beneficial. Many foods rich in GOS represent important protein sources for vegetarians and vegans (for example nuts, legumes, lentils and some soy-products), so improving tolerance to GOS containing foods may help to minimise dietary restrictions and ensure nutritional adequacy.

What foods to use it with: 

High GOS foods that this enzyme is likely to assist tolerance with include:

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


When to use it: This enzyme only targets GOS, so it should only be used when consuming GOS containing foods. As mentioned earlier, we also think that it is important to take the enzyme with food (half the dose immediately before the meal and half during the meal) to ensure that the enzyme travels through the gut with the food.

Where to get it: The enzyme is called 'alpha-galactosidase'. There are a number of different brands available, some with different doses. If you are based in Australia you will not find it on pharmacy shelves but it can be ordered online. 

Thank you to the wonderful members of our @monashFODMAP community who participated in this research study, we couldn’t do it without you!

If you want to read the full article see the link here: http://rdcu.be/u1j2. 

Reference: Tuck CJ, Taylor KM, Gibson PR, Barrett JB, Muir JG. Increasing Symptoms in Irritable Bowel Symptoms With Ingestion of Galacto-Oligosaccharides Are Mitigated by [alpha]-Galactosidase Treatment. Am J Gastroenterol. 2017.

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