How Stress Affects Your Digestion – Part Three

Stress, Your Immune System and Low “Good Bug” Levels

  • Do you have allergies or asthma?
  • Do you find yourself experiencing frequent sore throats, colds, or mouth ulcers?
  • Is it tough for you to shake off colds and flu when you get them?
  • Does it take longer than normal for wounds to heal – even small scratches and bruises?

If so, your gut could be creating a weakness in your immune system.

If you’ve read the previous two articles in this series, you’ll know that stress reduces blood flow to your gut, decreases your stomach acid levels, slows your stomach function and speed up your colon function.

If you haven’t read them, you can do so here:

H. pylori Symptoms, Stress and Digestion Article 1

H. pylori Symptoms Stress and Digestion Article 2

Any and every digestive symptom can result from these changes alone. Let’s take a look at two more ways you develop digestive symptoms due to stress.

Stress hormones affect your digestive system

When you consciously perceive stress, or when you have a bunch of stressful stuff going on in your body, your brain and nervous system trigger various responses.

Nerve and hormonal signals are sent to your adrenal glands, which sit on top of each kidney (hence the name “ad-renal”).

Kidneys And Adrenal Glands

This combination leads to the release of various stress hormones, including cortisol, adrenaline and noradrelanine (also known as epinephrine and norepinephrine).

These emergency hormones and nerve signals alter the way your body works. They reduce blood flow to your gut, slow your stomach, blunt your digestive secretions and increase colon function.

This causes a lot of problems: As well as causing symptoms in its own right, it stops you digesting food and encourages the overgrowth of bad bugs.

But that’s not all.

Over time, high stress hormone levels reduce the immune system power in your gut and create imbalances in your gut microbes.

Stress alters immune function in your gut

I’ve worked with lots of people who told me their digestive symptoms began after a period of stress.

Some folk reported a sudden reaction to certain foods that previously hadn’t caused any problems at all; others reported getting more colds and flu along with digestive symptoms. There are many patterns.

There’s an enormous amount of evidence showing how stress influences the immune system.

It can go either way: your immune system can become hyperactive, or it can be knocked down.

When we run home stool tests we look at something called secretory immunoglobulin-A, or sIgA for short. It’s a measure of gut immune function.

Sometimes it’s very high, indicating the immune system is reacting to something. On other occasions it’s very low, which tells us the immune system has been burnt out.

Cortisol, one of the major stress hormones, strongly influences the production of sIgA. High cortisol knocks sIgA levels down and low cortisol seen in adrenal fatigue means sIgA isn’t made in adequate amounts.

Changes in immune function can lead to food sensitivity and reactivity against microbes in your gut. Either or both can cause virtually any digestive symptom, and even more serious issues like colitis or Crohn’s disease.

Without wanting to get too technical, here’s an excerpt from a review paper explaining how immune activity may be hampered by stress:

The immunosuppressive effect of cortisol might also affect the conditions at the gut epithelium as well as gut bacterial composition. Repeated stressful events were associated with changes in the Bacteroides spp. population at the gut mucosa with consequences for the cytokine release by immune and epithelial cells of the gut.”1

Put simply, they are saying that cortisol affects the gut lining and gut bacteria, and increases inflammatory chemical release. All these factors end up leading to digestive symptoms.

Another paper by Karin de Punder and Leo Pruimboom says:

“Chronic psychological stress is known to dysregulate (imbalance) the immune system… low-grade inflammation, delayed wound healing, and increased susceptibility to infectious diseases.” 2

Stress alters the “good bug” population in your gut

A major reason for stress-related digestive symptoms is the alteration of gut bugs. As the previous quote suggests, stress causes changes in your gut bugs, and the changes are not generally beneficial.

You have trillions of these gut bugs and they’re vital for supporting digestion, immune function and overall health.

They make nutrients like vitamin K and biotin, protect colon cells and send signals to your brain.

As you can see below, imbalances in gut bugs are not only associated with digestive symptoms, but also depression, anxiety, obesity, arthritis diabetes and heart disease.3

Here’s a quick summary of how stress affects your gut bugs, according to Patrick hanaway, M.D.4

  • Reduces good bugs such as Lactobacillus and Bifidobacteria (studies were done on monkeys, not humans)
  • Encourages the overgrowth of several bad bugs, including disease-causing bacteria.
  • One of the best articles I’ve read on this topic by Blazquez and colleagues shows that bacteria such as E. coli, Salmonella, H. pylori, Listeria, Campylobacter, and Yersinia respond to stress hormones.5
  • These bacteria are mostly “gram negative” and produce toxins that can cause inflammation and damage to your stomach and intestine; they can also leak into your blood and cause body-wide symptoms.
  • Amazingly, anger and fear has been shown to increase Bacteroides fragilis levels (indicated as long ago as 1975).

We know for a fact – there’s no dispute – that changes in gut microbe levels are associated with digestive symptoms, and we know that stress affects microbe levels.

I believe that stress is one of the reasons why two people can carry round H. pylori or other bad bugs with completely different outcomes.

Person [A] might be under a lot of stress (from many causes) and have really nasty H. pylori symptoms, whereas person [B] who is comparatively calm may be unaffected.

This seems to be echoed by scientists in the field, as evidenced by Caso et al:

Stress can also synergize with other pathogenic factors such as Helicobacter pylori, non-steroidal anti-inflammatory drugs or colitis-inducing chemicals to produce gastrointestinal disease.” 6


It is clear that your stress level influences your immune system and since 60-80% of your immune system is in your gut, it makes sense that changes in immune function will create alterations in digestive function.

We also know for sure that your gut microbes are affected by stress. Some of the nastiest bad bugs seem to thrive when they’re exposed to stress hormones (especially noradrenaline) and some of the good guys are knocked down.

These bacteria can produce chemicals that are highly toxic to your stomach and intestinal lining, producing all the hallmark digestive symptoms (heartburn, bloating, irritable bowels and so on).

Why I Recommend a Home Stool Test

We typically observe a reduction in allergies and sinus problems, fewer colds and flu, better recovery from colds and flu (especially in winter months) and improvements in other immune-based symptoms when we help our clients improve their digestive health.

Running a home stool test is the quickest way I know to recover your digestive health, whilst boosting your energy, mood, and general well being.

It saves you time, money and reduces your stress level by giving you peace of mind.

It tells you which bad bugs you have, AND whether your good bug levels are optimal.

It also shows you whether you are digesting food properly, AND how your immune system has been affected by stress and other factors.

100% money back guarantee label (vector)

We’ve run more than 2,500 of these tests with folk from 23 different countries over the last half-decade, and we’d love to help you uncover the reason you’re not feeling well.

It’s a no-risk proposition: If the test doesn’t show you why you’re not feeling well, I’ll refund every penny.

If you want to check what’s causing your digestive symptoms, click here right now.

You won’t be disappointed.




I don’t make this information up – it’s all in the scientific literature and we see it day in, day out when we’re working with clients. Here are a some basic references for you to explore if you don’t feel comfortable about ordering a test and you’d like more info. Also, feel free to email us at if you have any questions.

1. Petra Ina Pfefferle and Harald Renz. The mucosal microbiome in shaping health and disease. F1000Prime Rep. 2014; 6: 11.

2. Karin de Punder and Leo Pruimboom.  Stress induces endotoxemia and low-grade inflammation by increasing barrier permeability. Frontiers in Immunology. May 2015: Vol 6; Article 223.

3. Augusto J. Montiel-Castro et al. The microbiota–gut–brain axis: neurobehavioral correlates, health and sociality. Frontiers in Integrative Neuroscience. Review Article; Oct 2013. doi: 10.3389/fnint.2013.00070

4. Hanaway, P. Lab examination of gut microbiota: A clinical discussion of molecular and culture techniques. Institute of Functional Medicine. 2011.

5. Blazquez, et al. Communication between bacteria and their hosts. Scientifica

Volume 2013 (2013), Article ID 361073, 15 pages.

6. Caso, JR et al. The effects of physical and psychological stress on the gastro-intestinal tract: lessons from animal models. Curr Mol Med. 2008 Jun;8(4):299-312.