Food & Nutrition Blog

Defining Digestive Health

By August 7, 2018 5 Comments
Aug 07
Beyond Resistant Starch

Open up the pages of any mainstream media today and you are likely to quickly spot the term “gut health”. As nutrition professionals, we are also inundated with medical literature discussing every aspect of gut health, whether that be the direct links to our brain activity or the controversial use of faceal microbial transplantation to treat a range of diseases.

But amongst all this discussion about this vital body organ, there appears to be very little consensus around the actual definition of “gut health” or a slightly more clinical term “digestive health”, despite the terms being used widely in scientific journals.1,2,3,4 Given our digestive system includes the salivary glands, mouth, oesophagus, stomach, liver, gallbladder, pancreas, small intestine, colon and rectum, it is big challenge for scientists to develop a simple yet relevant definition to encompass all digestive health.


The definition of health

The World Health Organisation defines health in a positive manner as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” 5

One could therefore extrapolate using this positive definition of health and define digestive health as overall positive mental and physical well-being in the absence of gastrointestinal disorders or disease. From a scientific point of view though, this definition would not be very clear and also does not provide physiological markers that can be measured to determine whether or not an individual is in a state of good digestive health. If the role of the gut is to perform at optimal functionality for the overall well-being of the host, then it is important to identify entities that can be used to assess gut functionality. The obvious entity that affects every aspect of gut functionality is the microbiome ecosystem.


The gut microbiome

The GI microbiome consists of about 1014 bacteria that are mainly located in the large intestine. There is plenty of evidence that a key functional entity required to achieve gut health is the gut microbiome. 6,7,8,9 The microbiome plays a number of roles in achieving and maintaining gut health, from preventing colonisation by pathogenic bacteria, to maintaining an intact GI barrier and regulating the immune system (see image below). Specific signs of a normal gut microbiome that may indicate positive digestive health include no bacterial overgrowth, normal composition and vitality of the gut microbiome and no gastrointestinal infections or antibiotic-associated diarrhoea. 10


Mechanisms of action of the intestinal microbiome on the gastrointestinal barrier

Mechanisms of action of the intestinal microbiome on the gastrointestinal barrier



The delicate microbiome ecosystem

Maintaining a healthy microbiome is like lawn care. With the right type of fertilising food (i.e. prebiotics), our turf (i.e. The beneficial microbes in our gut) will flourish. This delicate management of our gut ecosystem becomes even more important when interventions like antibiotics have substantially changed the number and composition of the gut microbiome. Without appropriate therapy, especially after a severe intervention, the ecosystem could become unbalanced, with less desirable microbes taking over, akin to weeds strangling a lawn. Although we are beginning to learn what a healthy microbial community looks like, our understanding of which strategies for altering the microbiota work best, and predicting which will work for a given individual, is still in its infancy.

The delicate microbiome ecosystem

Reference: Lozupone_et_al-2012-Nature. Diversity, stability and resilience of the human gut microbiata


Prebiotics – our gut fertiliser

If the gut microbiome is like the treasure chest in the search for the ultimate definition of digestive health, then prebiotics is the gold that is inside the treasure chest; the real treasure. The term ‘prebiotic’ as a concept was introduced around 20 years ago, though despite some revisions to its definition, there is still some variability in the definition used. The generally accepted consensus definition of prebiotics is ‘a substrate that is selectively utilized by host microorganisms conferring a health benefit.’ 11


Fructans – the ultimate gut fertiliser

Of all prebiotics, it is fructans that have received a lot of research attention regarding their beneficial health effects in humans, particularly around the area of gut health and bowel function.

Fructan prebiotics are polymers of (mainly) fructose and serve as the naturally occurring storage carbohydrates of a variety of foods including onions and garlic, cereals including barley and wheat, agave, artichokes, asparagus and leeks. Dietary fibre, of which fructans are a component, has well-known beneficial effects on human regularity (laxation), increasing faecal weight and transit time. Fructans are selective substrates for probiotic bacteria in stimulating probiotic bacterial growth, which can confer health benefits to the host and maintain a desirable microbial ecosystem, which is one of the entities required for optimal digestive health.

The role of fructans in digestive health

The arrival of fructans in the large bowel leads to an increase in fermentation by resident intestinal microflora. Short-chain fatty acids (SCFAs) are the end products of fructan fermentation by the bacteria of the colon and are absorbed and used by the cells of the human colonic epithelium, stimulating their growth as well as the absorption of salts and water, which increases the humidity of the caecal bolus through osmotic pressure, resulting in increased intestinal motility. 12 Fructans can therefore exert a favourable digestive health benefit by maintaining normal intestinal transit regularity and increasing stool frequency.


BARLEYmax®™ prebiotics support digestive health

Fructans are classified according to their degree of polymerisation (DP) into small (2 to 4), medium (5 to 10), and relatively large chain lengths (11 to 60 fructose units). The term FOS is used for shorter fructans with a DP of around 3–5 derived from sucrose while the term oligofructose is used for molecules with a DP of 3–10 derived from native inulin. 12 The fructan profile of BARLEYmax®™ whole grain is unique in that it is predominantly composed of fructans in the dp range of 3 to 12, which covers both FOS and inulin.

The Healthy Grain company has commissioned a strategic literature review outlining the evidence that BARLEYmax®™ barley prebiotics support digestive health.


On the basis of the positive conclusion of this SLR, The Healthy Grain company has formally notified FSANZ (Food Safety/Standards Australia and New Zealand) of this health claim.  If you would like to know more about The Healthy Grain SLR and BARLEYmax®™ prebiotics, let us know in the comments below or send us an email and we will be in touch.


Yours in Nutrition,





Teri Lichtenstein (APD)
The Healthy Grain Nutrition Ambassador


  1. Tuohy KM, Probert HM, Smejkal CW, Gibson GR: Using probiotics and prebiotics to improve gut health. Drug Discov Today. 2003, 8: 692-700. 10.1016/S1359-6446(03)02746-6
  2. Ferguson LR, Shelling AN, Lauren D, Heyes JA, McNabb WC, Nutrigenomics New Zealand: Nutrigenomics and gut health. Mutat Res. 2007, 622: 1-6. 10.1016/j.mrfmmm.2007.05.001
  3. Johnson IT: Gut health, genetics and personalised nutrition. Genes Nutr. 2007, 2: 53-54. 10.1007/s12263-007-0020-y.
  4. Jacobs DM, Gaudier E, van Duynhoven J, Vaughan EE: Non-digestible food ingredients, colonic microbiota and the impact on gut health and immunity: a role for metabolomics. Curr Drug Metab. 2009, 10: 41-54. 10.2174/138920009787048383
  5. World Health Organization.Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19–22 June 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948. In Grad, Frank P. (2002). “The Preamble of the Constitution of the World Health Organization”. Bulletin of the World Health Organization. 80(12): 982.
  6. Fasano A, Shea-Donohue T: Mechanisms of disease: the role of intestinal barrier function in the pathogenesis of gastrointestinal autoimmune diseases. Nat Clin Pract Gastroenterol Hepatol. 2005, 2: 416-422
  7. Nieuwenhuis EE, Blumberg RS: The role of the epithelial barrier in inflammatory bowel disease. Adv Exp Med Biol. 2006, 579: 108-116. full_text.
  8. Meddings J: The significance of the gut barrier in disease. Gut. 2008, 57: 438-440. 10.1136/gut.2007.143172
  12. Schaafsma G, Slavin JL. Significance of Inulin Fructans in the Human Diet. Compr Rev Food Sci Food Saf 2015;14:37-47.

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