Thanks to Jenni Visuri, student on the Graduate Entry Medicine course at Oxford University, for putting this piece together. See Jenni’s previous piece on the relationship between soy and breast cancer here.
You’re not completely human. A whole host of tiny organisms live in your body outnumbering your human cells 10 to 1. Science-fiction? Not in the slightest! Meet your microbiota…
The microbiota is made up of approximately 10 trillion bacteria, fungi and other organisms that live in our bodies, mainly in the digestive tract. Whilst we only really think about bacteria when we’re fighting off an infection, the majority of the bacteria in our bodies are actually beneficial. Our body has a symbiotic, or win-win relationship with these microorganisms which aid with many processes including digestion. These little critters work hard in the background, all while you’re working, eating and sleeping.
Gut’s the issue?
With modern stressful lifestyles, Westernised diets, and medications such as antibiotics, the bacteria living in your gut can be thrown off-balance. Over the years, the microbiota has been found to have a profound effect on human health and disease. It has the power to increase energy extraction from food, increase nutrient harvest, and alter appetite
signalling. It also competes with bad bacteria that may enter the body by competition and production of antimicrobial substances. Finally, it is essential for development of the intestinal mucosa and the immune system.
There are many bacteria that can alter the microbiota that result in gastrointestinal upset such as C. difficile and H. pylori. Whilst these infections are normally not serious, the effects on the microbiome can also result in more serious problems such as gastric or colorectal cancer. It can even have an effect on metabolic disorders such as obesity, so basically your gut bugs could be causing you to put on more weight. Type 2 diabetes can also be influenced by your gut microbiota because the mechanisms that cause the disease may be related to the translocation of gut microbiota from the gut to the tissues thus inducing inflammation. However, the list doesn’t end there. The list of diseases which seem to be affected by the microbiota is constantly growing, with some research suggesting that Parkinson’s , arthritis and allergies could be something to do with our gut bacteria (1,2).
Recent studies have revealed the importance of the microbiota to the central nervous system, and bidirectional communication between the central nervous system and the gut has long been recognised. The different pathways of communication between the brain and the gut include the autonomic nervous system, the enteric nervous system, the
neuroendocrine system, and the immune system. Studies are beginning to highlight that the gut microbiota is having a large influence on the central nervous system function, notedly an influence on the brain and mood. (3)
The microbiota is involved with how stress affects the body and the bacteria are known to be involved in some of the stress-induced changes in inflammation. Stress increases intestinal permeability which allows bacteria to travel across the intestinal mucosa to access immune cells neuronal cells of the enteric nervous system. Further studies have shown that behaviour is affected when the bacteria in the gut is manipulated. A higher amount of inflammation in the gut was linked to increased anxiety-like and depressive behaviours. Probiotic treatment where patients were given bacteria showed an improvement in their depression. (4)
Listen to your gut
So what can we do to nurture our microbiota? This is where the concepts of prebiotics and probiotics come in. Prebiotics are foods that promote the growth of healthy gut bacteria, probiotic foods actually contain live cultures. Prebiotic foods are high in a specific type of fibre, and include foods like bananas, leeks, artichokes, onions, garlic and wheat bran. Adding in a wide variety of fruit and vegetables into your diet will help promote gut health, and also give you a healthy dose of fibre, vitamins and minerals whilst keeping you fuller for longer. Probiotic foods are certain types of fermented food so contain a wide variety of bacteria -although not all fermented foods are probiotics! Examples of foods that typically contain beneficial bacteria include; live yoghurt, kefir, kombucha, sauerkraut, kimchi, pickles, tempeh, miso and some types of cheese made from unpasteurised milk. When buying these foods, ensure you’re picking ones that are kept refrigerated because unfortunately anything with a long shelf life will have been heated and no longer contain live bacteria. You can find some of these products in supermarkets and health food shops or look up recipes to make your own!
Probiotics are also available in pill form, but eating probiotic foods is more beneficial as you will be exposed to more strains of bacteria than in a pill which often contains just a single strain. Probiotic pills can also be expensive whereas you can make your own sauerkraut or kombucha for much less. Other advice for better gut health involves exercise, stress
reduction, and reducing consumption of processed foods, sugary foods and alcohol.
Gut’s the future?
We’re at the stage in science where we can pay to get our gut screened to understand which microorganisms are present in our body. There are plenty of websites offering at- home test kits which will try and identify if there are any bacteria in your microbiota that are attributed to different illnesses such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and metabolic disorders. But don’t run to get tested yet! Whilst these processes are all scientifically sound, it’s incredibly difficult at the moment to draw any conclusions as to what the results mean, or to decide what actions need to be taken.
Additionally, they’re incredibly expensive. It’s best to just stick to the sauerkraut for now!