When it comes to improving your overall health, regardless of whatever outcome you are trying to achieve, one of the first things that you should be doing is prioritising your gut health. Your gut, and more specifically your gut microbiota, influences almost every other aspect of your physical wellbeing. So, if you’re trying to lose weight, balance your hormones, strengthen your immune system or simply maximise longevity and reduce your risk of chronic disease, it makes sense to start thinking about looking after your gut ASAP.

What is the ‘gut’?

Once food has been digested and broken down in the stomach and small intestine, where most of the nutrients are absorbed into the bloodstream, food enters the large intestine where water is removed and stool formation begins. The large intestine and colon are host to an average of 160 different species of bacteria, with a combined greater genome than the human genome itself. Collectively, this bacteria is known as the microbiota. The microbiota is largely determined during fetal development and the breastfeeding stage, and then influenced by our diet and environment around us as we grow. The role of the microbiota is to produce enzymes which are not produced in the body, essential vitamins (vitamin K and several of the B vitamins), and to break down polysaccharides and polyphenols.

Out of all of these roles, it seems as though one of the most interesting tasks of the gut microbiota is quite likely the production of short chain fatty acids (SCFAs). Polysaccharides are the main source of fuel for the gut bacteria, which are then broken down into SCFAs. The polysaccharides the bacteria feed on are the ones which are otherwise indigestible, also known as fiber. Fiber is found in all plant based foods, and a variety of the types of fiber in our diet ensures that we can maximise short chain fatty acid production.

What do short chain fatty acids do?

SCFAs have a large number of beneficial roles in the body, as they behave similar to neurotransmitters. They can reduce appetite, regulate glucose homeostasis and regulate triglyceride homeostasis. This means that SCFAs have a potentially beneficial role in obesity treatment and the prevention of metabolic related diseases such as type 2 diabetes, non-alcoholic fatty liver disease and cardiovascular disease.

SCFAs also have a role in aiding the absorption of calcium into the bone matrix, meaning they could play a role in the prevention of osteoporosis.

SCFAs are also proven to induce apoptosis (cell death) of cancerous cells, particularly in the colon. As well as destroying cancerous cells, SCFAs can strengthen the cell wall components of the colon.

In the absence of enough fuel for the bacteria in the gut, (i.e. low carbohydrate diets for an extended period of time with little fiber- OR highly processed diets with fiber removed), the bacteria can turn to alternative fuel sources instead, which can lead to the production of potentially harmful metabolites instead.

Inflammation and the gut

Most modern diseases are a direct result of chronic inflammation in the body. Inflammation is not always a bad thing, in fact it is necessary for when the body is wounded or unwell to create inflammation, so that white blood cells and antibodies can foster quick healing of the wound or sickness. However, chronic inflammation as a result of high levels of inflammatory cytokines in the bloodstream places stress on the immune system and increases our likelihood of other diseases. For example, cardiovascular diseases and cognitive disorders such as Alzheimer’s Disease are inflammatory conditions. It is therefore beneficial to consciously attempt to keep inflammation low- which we can do so by prioritising gut health.

Not only is the gastrointestinal tract home to 70-80% of the body’s immune cells, but a weakened gut lining can be responsible for the increase of inflammation in the body as well. Disrupting the balance of good and bad bacteria in the gut weakens the lining of the intestinal epithelium, allowing inflammatory cytokines to enter the bloodstream and lead to systemic inflammation in the rest of the body.

Looking after the gut

With the exception of people who have irritable bowel syndrome, or other serious gastrointestinal diseases, increasing the amount of dietary fiber is generally beneficial for the majority. We should be aiming for 25-30 grams per day, when the average is currently around 15 grams. Soluble types of fiber are the most beneficial for the production of short chain fatty acids. This is found in oats, apples, peas, beans, carrots and psyllium- as some good examples. Insoluble fiber is also extremely helpful for promoting faster digestion and preventing the build up of toxins in the gut. All vegetables, whole grains, nuts, legumes and seeds contain insoluble fiber. Some people are more tolerant to higher amounts of fiber than other people. It is not uncommon to experience bloating or increased abdominal pain if you try to increase fiber by too much too soon. It is better to slowly increase the amount of fiber in your diet, focusing more on diversity of fibers and getting a balance of soluble and insoluble.

As well as consuming more fiber, taking probiotic supplements can be very helpful for people with digestive issues. These people may also benefit from an elimination diet, such as the low FODMAP diet, to help initially remove foods that could be causing inflammation, allowing the gut lining to repair, before slowly introducing those foods back into the diet.

General healthy habits also seem to play a huge role in maintaining the balance of good bacteria, including reducing stress, regular exercise, limiting alcohol, quitting smoking, eating slowly, drinking plenty of water, minimising the use of antibiotics as much as possible and limiting fried foods and highly sugary foods as much as possible.

References:

https://www.mdpi.com/2072-6643/13/9/3172/htm

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2785020/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726210/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847071/

https://onlinelibrary.wiley.com/doi/10.1111/jgh.12322

https://www.mdpi.com/2072-6643/13/10/3513/htm

https://www.mdpi.com/2076-2607/9/11/2184