Your gut instinct

News posted by Nikki Harris

Immune health – it all comes back to the gut

The ‘gut’ has a lot to answer for, particularly when it comes to our immune health! Did you know that approximately 70% of our immune system is located in our digestive tract (also known as our GUT).

What is our immune system?

It is the body’s defence system, offering protection against foreign invaders and pathogens (germs). The lining of the digestive tract contains our gut immune system referred to as GALT – gut associated lymphoid tissue. This plays a vital role in helping to block external toxins and pathogens and exists to communicate with the rest of our immune system. GALT works in partnership with our gut microbiome (gut bacteria) and together they have the job of helping to keep us safe.

The innate & adaptive immune system

Our innate immune system is sometimes referred to as our in-born immune system and it is the first part of our immune system to respond to invaders. Within hours of an antigen’s appearance in the body, our non-specific defence mechanisms such as the skin, chemicals in the blood and immune system cells begin to launch an attack on the foreign invaders. The innate immune system then communicates with the adaptive immune system (often referred to as our acquired immune system) in an attempt to ensure that the foreign invader or antigen is remembered. In this way, the next time that the body encounters the same invader, the response rate is much quicker.

The protective mucous membrane of the digestive tract lining is also important for helping to prevent invaders from entering the bloodstream, alongside providing a home to the beneficial bacteria and immune cells that reside in the gut. However, for some people this mucous membrane may become inflamed and overly porous, allowing invaders and pathogens to escape, squeezing their way through into the bloodstream. This is commonly referred to as ‘leaky gut’ or ‘intestinal permeability’.

Undigested food particles and toxic waste may also leak from the intestinal wall into the bloodstream, provoking an immune reaction and signalling for GALT to take action. It is the GALT which is responsible for activating an inflammatory and immune response in the body. For some people, this may give rise to symptoms such as:

  • Food sensitivities
  • Digestive problems: bloating, gas, constipation, diarrhoea, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD)
  • Headaches
  • Weight gain
  • Fatigue
  • Skin issues
  • Thyroid issues
  • Autoimmune conditions e.g. rheumatoid arthritis

What causes leaky gut?

Amongst a long list of possible contributors to leaky gut, gut dysbiosis is a strong contender. Simply put, this refers to a state of imbalance between the friendly and unfriendly bacteria in the gut. Factors that may fuel this state of imbalance may include diets high in sugar and processed foods, alcohol, stress and toxins produced from some medications (e.g. birth control pill, antibiotics, pesticides, chemicals in food and food packaging, environmental pollutants and some foods such as gluten, dairy and caffeine).

Gut support – ‘human microbiome’

Our microbiota is a companion that will accompany us through life.


There are over 100,000 billion microbes in the intestine, with 2000 species and 7000 strains. Our intestinal microbiota weights approximately 1.5kg (most of which is housed in the large intestine) and produces about 2 litres of gas per day. So, when it comes to choosing the right supplement it is worth considering that 20 -30 billion live cultures is a mere drop in the ocean when you consider the fact we have over 100, 000 billion microbes in the gastrointestinal tract!

Typical microbiota of the adult gastrointestinal tract

The small intestine harbours most of our immune system and as we travel further down into the gut so our bacteria levels increase.  But why are there such major differences in small intestinal and large intestinal numbers of microbes?


Did you know that the small intestine is approximately 20 ft long, hence giving rise to a faster transit time for the food we eat, approximately 2-4 hours compared to the large intestine (often referred to as the colon) which is just 4 foot long with a slower transit time of 18-90 hours.

The small intestine is the site where the majority of the absorptive processes in the body take place (e.g. nutrients and vitamins from the food and drink we consume). The small intestine is also the site of major immune, endocrine and neural functionality.

For a probiotic formula to be effective, it must arrive ‘alive’ to the intestinal tract. Since the stomach is highly acidic (and may potentially destroy the bacteria) some may argue that we should look for those supplements with an enteric coating which helps to protect the bacteria from the acid environment, ensuring delivery to the large intestine where most of our gut microbiome is housed. However, there are also discussions that suggest the presence of an enteric coating may also inhibit the breakdown of that coating in sufficient time for it to have a beneficial impact on the small intestine due to the fast transit time of 2-4 hours. So what is the answer for supplying therapeutic potencies?

Supporting gut health

There are many factors to consider when deciding on which bacteria supplement to take. A major consideration is the therapeutic potencies of lactobacilli live bacteria (which supports the small intestine) and bifidobacteria (which supports the large intestine – home to many more bacteria).

  1. A great way to kick start gut health is to look at reducing the amount of sugar and processed foods in your diet! Not only is sugar an anti-nutrient (meaning the body uses up vital stores of vitamins and minerals in processing it), but it also feeds the ‘unfriendly bacteria’.
  2. Re-populate the ‘friendly’ bacteria in your gut by introducing live beneficial bacteria. Good food sources include natural yogurt containing ‘live’ cultures, kefir, goat’s milk, sheep’s milk and A2 cow’s soft cheeses, apple cider vinegar and cultured vegetables (sauerkraut and kimchi).
  3. Try and include prebiotic-rich food into your diet (aiming for approximately 5g daily). Prebiotics are a type of un-digestible fibre that act as food for probiotics. In other words the probiotics eat prebiotics. Prebiotic dense foods include: raw garlic, onion, raw asparagus, raw leeks alongside some not so common cupboard staples such as raw chicory root, Jerusalem artichoke and raw dandelion. Many are available from good health stores and can be added to salads and pasta dishes.
  4. Very high potency probiotics are required to yield effect in the large intestine (e.g. 100 – 2000 billion) compared to the small intestine (where the site of most prebiotic activity is more in the region of 2-25 billion).
  5. Supplementing with a high potency probiotic that contains multiple strains of bacteria and therapeutic levels of both lactobacilli and bifidobacterium is a good idea. For those with IBD, severe constipation or IBS you may like to consider a higher colon care 80 billion probiotic.

Contact Emma at Woburn Osteopaths for a bespoke nutrition consultation: [email protected] / 01525 290615. 


  1. Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. Chapter 24, The Adaptive Immune System.Available from:
  1. Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. Innate Immunity.Available from:
  1. Dr. N Plummer. PhD

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