30 April 2018

Food additives and FODMAPs

Food additives

By Lyndal McNamara - Research Dietitian

A commonly asked question we receive is, ‘which E numbers or food additive numbers should I look out for in ingredients lists when following a low FODMAP diet’?


But firstly, what exactly are ‘E numbers’ or ‘food additive numbers’? 

E numbers’/’food additive numbers’ are simply a numbering system that is used internationally to describe different types of food additives. An ‘E’ is used before the number in countries that are part of the European Union and simply stands for ‘Europe’. Regardless of which part of the world you live in, the number can be used to identify the type of food additive. For example; 


  • E100-199 = colourings 
  • E200-299 = preservatives 
  • E300-399 = antioxidants & acidity regulators 
  • E400-499 = thickeners, stabilisers & emulsifiers 
  • E500-599 = acidity regulators & anti-caking agents 
  • E600-699 = flavour enhancers 
  • E700-799 = antibiotics 
  • E900-999 = glazing agents, gases & sweeteners 
  • E1000-1599 = additional additives 


So which food additives can be problematic if I have IBS? 

While most food additives have not been studied specifically in people with IBS, there are several that have known gut side effects. 

The most well know include sugar polyols, which are widely used as ‘sweeteners’ in foods, but can also be found in certain medications (particularly those in liquid form). Some examples of common sugar polyols used as food additives include: 

  • Sorbitol (E420/420) 
  • Mannitol (E421/421) 
  • Isomalt (E953/953) 
  • Maltitol (E965/965) 
  • Lactitol (E966/966) 
  • Xylitol (E967/967) 


What effects do these sugar polyols have in the gut? 

Certain sugar polyols are well known for their ‘laxative’ effects, even in people without IBS – that is, when eaten in large enough amounts, they can cause gut symptoms. This is because they: 

  • Cause extra water to be dragged into the gut, which can make stools more liquid or soft and result in diarrhoea.  
  • Can be poorly absorbed in the small intestine. Unabsorbed sugar polyols then reach the large intestine where they are digested by the bacteria that live there, resulting in gas production – this can lead to symptoms like bloating, cramps, flatulence and tummy pain. 

See our blog all about polyols and our IBS animation for more information about these effects in people with IBS. 

The important thing to remember is that everyone with IBS will tolerate sugar polyols differently. In fact, people with constipation predominate IBS (IBS-C) may actually find the laxative properties of sugar polyols useful for improving their constipation (when consumed in the right dose for them). 


Are there any sugar polyols that do not have gut side effects? 

Yes! In fact the smallest of the sugar polyols, glycerol (E422/422), is easily absorbed in the small intestine (upper gut), so does not have the same effects in the body as other larger sugar polyols. Erythritol (E968/968) may be the other exception, as it also appears to be well absorbed in the small intestine. (1, 2) One study showed that Erythritol is more difficult for bacteria in the large intestine to break down, so might be less likely to cause gas or bloating symptoms than other sugar polyols (even when it is malabsorbed), but more research is needed to clarify this. (1) Unfortunately, the effects of Erythritol have not been studied in people with IBS, so whether or not this is a problematic polyol for people with IBS remains unclear. (2)   


So what does this all mean for me? 

  1. Stick to mostly fresh, minimally processed foods! These are generally better for overall health and far less likely to contain food additives in the first place. 
  2. During the first phase (restrictive phase) of a low FODMAP diet, we recommend avoiding foods naturally high in sorbitol and mannitol (refer to the app) and processed foods containing the sugar polyols listed above (except glycerol). 
  3. If you notice these sugar polyols are in certain medications you require, speak to your pharmacist for advice – there may be an alternate formulation or brand that you can buy that does not contain these ingredients. They may also be present in very small quantities that are unlikely to cause gut side effects – again, ask you pharmacist or doctor for advice if you suspect a medication may be worsening your symptoms. 
  4. When your symptoms are well controlled, progress to phase two of the diet and re-challenge foods naturally containing sugar polyols (i.e. sorbitol and mannitol) to work out your level of tolerance. Re-introducing some high polyol foods may be especially useful for people with constipation predominate IBS (IBS-C). Speak to your dietitian for more advice about FODMAP re-challenge. 


References: 

  1. Arrigoni E, Brouns F, Amadò R. Human gut microbiota does not ferment erythritol. British Journal of Nutrition. Cambridge University Press; 2005;94(5):643–6.
  2. Lenhart A, Chey WD. A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome. Advances in nutrition (Bethesda, Md). 2017;8(4):587-96. 


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