Upset Stomach? Here Are the Signs to Look Out For

It might sound hard to believe, but every person has a vast range of bacteria, fungi and viruses in their gut. These microbes form a ‘microbiome.’ The microbiome is responsible for converting food into energy, ensuring a healthy immune system, and disposing of harmful germs.

Research from the last twenty years links our health and happiness to the balance of bacteria in our stomach. Illness, stress and certain foods can cause an upset stomach. When the digestive system is underperforming, tell-tale symptoms crop up throughout the body. Here are some of the signs to look out for.

Changes in mood

There has been a lot of research in recent years showing the link between the gut and brain. The connection is sometimes called ‘the gut-brain axis.’ In 2017, a study found that inflammation of the stomach can change the mood and make a person more vulnerable to anxiety and depression. (i)

Fortunately, probiotics can restore a healthy balance of bacteria in the stomach and reduce psychological symptoms. (i) Increased stress, anxiety and depression may well be a sign of a sick stomach.

Allergies and autoimmune conditions

Medical researchers have found links between the gut and the immune system. When the stomach is unhealthy, our immune systems might not work correctly, leading to autoimmune diseases. An autoimmune disease is where the body’s immune system gets confused and targets itself instead of harmful foreign bodies. (ii)

A specific type of gut bacteria, called Bacteroides fragilis (B. fragilis), can be linked to the onset of rheumatoid arthritis, multiple sclerosis and other autoimmune conditions. The bacterium produces a protein called ubiquitin, which might be the puzzle piece responsible for triggering autoimmune disease. (iii)

A study published in 2018 found that an upset stomach can play a significant role in causing specific allergies. The allergic conditions include food allergies, skin allergies and allergies that affect your airways. (iv)

Sugar and chocolate cravings

There is a link between the microbes in our gut and our eating behaviour. This is because microbes in the gastrointestinal tract are under constant pressure to influence our eating behaviour, to help them grow and dominate the environment within our gut.

The good and bad bacteria in your gut can be knocked out of balance by eating sugary foods. In addition, consuming lots of sugar can promote harmful bacteria, generating cravings for more sugar.

A study published in 2014 recommends changing the balance of bacteria in your gut microbiome if you want to reduce cravings for sugary food, like chocolate. (v) This works because the gut microbiome can be easily manipulated by prebiotics, probiotics, antibiotics and dietary changes.

Tiredness and fatigue

In 2017 a study found that people with chronic fatigue syndrome might have issues with the balance of their gut microbiome. Sleep disturbances and fatigue can be linked to an unhealthy gut. (vi)

The neurotransmitter serotonin plays a crucial role in regulating our mood and sleep. Because the bulk of serotonin production occurs in the gut, any disturbances to the gut microbiome could affect our ability to fall asleep and feel rested when we wake up.

Stomach pain or discomfort

Symptoms including bloating, gas, constipation, diarrhoea or pain could be signs of Irritable Bowel Syndrome (IBS). (vii)

IBS is one of the most common forms of gastrointestinal disorder that affects the large intestines. Recent studies have shown that imbalances in gut bacteria might be behind IBS. (viii)

When there is an imbalance in the number of harmful bacteria in the gut, excess gas can be produced during the normal digestive process. The extra gas can cause severe discomfort, bloating and heartburn. Bringing the microbiome back into balance with probiotics and prebiotics may help with an upset stomach. Eat natural probiotics. These can include plain yoghurt, kimchi, sauerkraut and kefir. These foods contain good bacteria produced during the fermentation process. (ix)

  • Get more fibre in your diet. About 25 grams of dietary fibre per day. (ix)
  • Drink enough water and limit your daily intake of caffeine. As a stimulant, caffeine can disrupt the process of digestion and dehydrate you. (x)
  • Speak with your doctor if you experience frequent constipation or diarrhoea. What happens in your stomach has a direct impact on your overall health.


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  2. Brown, K., DeCoffe, D., Molcan, E. and Gibson, D.L. (2012). Diet-Induced Dysbiosis of the Intestinal Microbiota and the Effects on Immunity and Disease. Nutrients, [online] 4(8), pp.1095–1119. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3448089/ [Accessed 25 Jun. 2021].
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  6. Nagy-Szakal, D., Williams, B.L., Mishra, N., Che, X., Lee, B., Bateman, L., Klimas, N.G., Komaroff, A.L., Levine, S., Montoya, J.G., Peterson, D.L., Ramanan, D., Jain, K., Eddy, M.L., Hornig, M. and Lipkin, W.I. (2017). Fecal metagenomic profiles in subgroups of patients with myalgic encephalomyelitis/chronic fatigue syndrome. Microbiome, [online] 5(1). Available at: https://link.springer.com/article/10.1186/s40168-017-0261-y [Accessed 25 Jun. 2021].
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  9. Piedmont.org. (2021). Ten Tips To Keep And Maintain A Healthier Gut | Piedmont Healthcare. [online] Available at: https://www.piedmont.org/living-better/10-tips-for-a-healthier-gut [Accessed 25 Jun. 2021].
  10. Piedmont.org. (2021). Family Physician Shares Signs of Poor Gut Health | Piedmont Healthcare. [online] Available at: https://www.piedmont.org/living-better/signs-of-poor-gut-health [Accessed 25 Jun. 2021].

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