WHAT IS THE GUT MICROBIOTA?
The gut microbiota is the name given to the 40 trillion strong microbe population living in our intestines. The composition of the gut microbiota is unique to each individual (even identical twins) and can be affected by many factors including poor diet, medications, stress and ageing.
WHAT DOES THE GUT MICROBIOTA DO?
It helps the body to process indigestible foods that the stomach and small intestine have not been able to digest.
Production of some vitamins (B and K).
Helps in the maintenance of the intestinal mucosa, and proper digestive functioning.
It plays an important role in immunity, and has also been linked to food cravings, mental health, diabetes, heart disease and overweight/obesity.
WHAT SHOULD YOU FEED YOUR GUT MICROBIOTA?
Foods containing fibre and/or resistant starch feed good bacteria that produces short-chain fatty acids, B vitamins & antioxidants (Fig 1 - right-hand side). These have anti-inflammatory & anti-carcinogenic effects and promote a healthy gut and therefore a healthy you. High protein, high fat diets promote the opposite to this (Fig 1 - Left-hand side).
Figure 1 O’Keefe (2016) Nature Reviews
IT'S ALL ABOUT DIVERSITY
In such an emerging scientific area that is largely based on theories and association, one thing everybody agrees with is that diversity is key. In a study conducted by David et al. (2014), you can see a significant reduction in gut microbiota diversity in a subject that travelled to Asia from metropolitan USA (Fig 2). This reflects a change in macronutrient distribution (carbs, fat & protein) to a predominantly animal based eating pattern and development of associated microorganisms capable of triggering inflammation in the gut (e.g. Proteobacteria in green). This also highlights that it doesn't take long to go from a healthy gut to an unhealthy gut (and visa versa).
Figure 2 David et al. (2014)
THE EASIEST WAY TO DETERMINE WHETHER YOUR GUT IS HEALTHY
According to a study by Vandeputte et al. (2016), stool consistency is strongly associated with gut richness and composition. Be the private investigator and measure your poo against the 'Bristol Stool Chart'. The ideal consistency is somewhere between type 3 and 4.
Figure 3 Bristol Stool Chart
So how many times should we be visiting the toilet? The average is once per day, but anything between 3 times per day to 3 times per week is normal, as long as your eye balls aren’t falling out of their sockets (e.g. poo is neither too hard nor too loose).
PREBIOTICS VS PROBIOTICS
Prebiotics are food for probiotics. Prebiotics are found in asparagus, Jerusalem artichokes, leeks, onions, tomatoes, garlic, spinach, oats, barley, nuts and seeds, beans, chickpeas, lentils and supplementary fibres, such as psyllium. Resistant starches, such as green bananas, Hi-Maize Corn Starch and cooked cooled pasta and potatoes have a similar beneficial impact on your gut microbiota.
Nb: If you are living with a gut condition (e.g. IBS), many of the above foods could trigger symptoms. Please seek advice from an Accredited Practising Dietitian with expertise in gut health, to best manage your condition and your gut.
Do probiotcs actually work? Researchers are still trying to understand what constitutes a healthy gut microbiota. This is because it varies from person to person. Therefore, one probiotic may work for one person, but not for the next. One thing scientists agree on is that there's no need to take probiotics if you already have a healthy gut.
The most evidence for a beneficial effect from taking probiotics is in relation to diarrhoea caused by antibiotics, and irritable bowel syndrome. However, results are mixed. For probiotic supplements, particularly in Australia, it is a watch this space I'm afraid.
The probiotic effects of fermented foods are all the hype at the moment. Foods like yoghurt, kimchi, sauerkraut, kefir and natto (miso soup) have all been shown to improve gut health in some people. Most have been around for centuries. Kombucha has burst into our food supply recently, however, the evidence is behind compared to the other foods.
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