This is fast becoming another term used by food industry marketers, emblazoned on food packaging to persuade us to choose their brand. But what is ‘gut health’ – is it merely an absence of gut disease? With up to one in five people in the UK developing Irritable Bowel Syndrome at some stage in their life, and the widespread use of over-the-counter medications aimed at the digestive system, you could say the marketers are identifying another significant market category.

As an isolated claim, ‘good for gut health’ is usefully vague enough to slip past rigorous legislation aimed at preventing the use of spurious health claims used to help sell products. But ‘Gut health’ should not only signify an absence of gastrointestinal (GI) disease and a symptom free status, it should also encompass:

  • Effective digestion
  • An effective mucosal surface (that absorbs nutrients, whilst also being a barrier to pathogens)
  • Effective, balanced immune tolerance (to the dietary nutrients passing through)
  • A good habitat for the microbial populations (that serve to enhance the gut’s barrier, digestive and immune functions).

Because those are all necessary functions of a healthy gut, and if any of them falters, gastrointestinal discomfort and risk of disease is just around the corner.

Defining gut health is one thing, but actually measuring the complex mechanisms it encompasses is another. Historically the focus of healthcare has been to investigate, measure and diagnose disease or a state of pathology, so can ‘gut health’ being an absence of disease and a goal that sits within the realm of disease prevention, actually be measured?

Positive health goals and disease prevention is very much the domain of Functional Medicine practitioners trained in Nutritional Therapy, who work upstream to optimise intestinal function rather than simply suppressing downstream GI symptoms. Working upstream they need to be able to assess GI function within objective parameters, and will employ an armoury of functional tests to this end. It’s worth pointing out here that a well functioning GI tract has been shown to contribute to health in many other ways beyond the intestines, including mood, mental health and the immune system.

Functional Tests

The two main functional entities that are central to gut health are the GI microbiota (the trillions of beneficial bacteria we play host to in our gut), and the GI barrier (made up of bacteria, brush border mucous, nerves and epithelial cells lining the intestines, and designed to absorb nutrients).

Our GI microbiota co-exist with us in a mutually beneficial relationship, contributing to our metabolism as well as our immune systems. Their numbers and diversity help to keep opportunistic colonising pathogens in check. This resident microbiota can be measured via stool samples using DNA-based sequencing technologies, and the greatest microbial diversity is associated with positive gut health. Such testing can then inform therapeutic probiotic protocols.

Our GI barrier function can also be tested, as abnormal permeability – where the gut surface may be behaving more like a colander than fine cheesecloth – can result in undigested food and other particles trafficking through the gut lining to the bloodstream. Such incursions can upset the delicate balance between tolerance and an immune response causing inflammation, as well as infectious and inflammatory GI diseases, autoimmune conditions and multiple health problems.

A measure of gut hyper-permeability can be shown using blood tests that might reveal increased presence of bacteria specific antibodies or immune complexes to undigested proteins or viruses. In the event of an overly leaky gut being revealed, a nutritional therapist will first identify the likely causes of the leakiness, then embark on dietary protocols designed to restore the integrity of the gut’s barrier.

Effective Digestion is the third entity that is measurable. Digestion and metabolism is the process by which your body converts the food you eat into energy and structural repairs. The vitamins and minerals in your food also support myriad, complex processing functions, chemical reactions and the nervous system. So knowing you’re getting what you need from your diet is extremely useful.

Such knowledge is possible by analysing Organic acids in urine. This assesses the sufficiency of your digestive enzyme production, how well foods are actually being digested, and precisely what nutrients from a person’s diet are actually being absorbed and utilised, and conversely – what may be lacking. By identifying any weaknesses in a person’s metabolism, or inadequacy of digestive function, or nutrient shortfall, dietary protocols can be tailor made to the individual’s requirement. When it comes to diet, one size does not fit all and different lifestyles that put different stresses on metabolism result in varying nutrient needs.

With research now showing the health of our guts has profound effects on the other systems of our bodies, ‘Gut Health’ needs to be everyone’s goal. Functional Medicine that looks upstream to optimise the health of all the body’s systems represents a very useful adjunctive approach to healthcare, because by improving the body’s ability to function well and bring back into balance any systems that are veering away from the optimum, will support the body’s very real ability to heal itself. These practices represent effective strategies in preventive medicine that could make a meaningful contribution towards keeping our health systems more affordable.


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Arora SK et al., (2015) Microbiome: Paediatricians’ perspective. Indian J Med Res. 142(5):515-24.

Sturgeon C, Fasano A. (2016) Zonulin, a regulator of epithelial and endothelial barrier functions, and its involvement in chronic inflammatory diseases. Tissue Barriers. 4(4):e1251384.