Or to be more accurate, what to eat to encourage beneficial micro-organisms to inhabit and proliferate in your large intestine (colon).
Gut health is all the rage and with good reason. Increasingly research points to an important relationship between the micro-organisms (‘gut bacteria’ to use a common but not entirely accurate term) that live inside your body and your state of health, both physical and mental.
In the womb, a baby’s future health and immunity are already being influenced by the diet, habits and mental state of the mother through her gut microbiota. When a baby is born vaginal delivery imparts the mother’s set of micro-organisms to the baby. If delivery is by Caesarean section the baby does not get this important ‘starter’ of bacteria species. This is ‘ground zero’ but from then onwards the baby’s gut flora are influenced by environment, diet, stress/trauma and so much else. Interested to know what else? Read this.
Most of the research into dietary influence on gut microbiota has been done on animals, but an important study by De Filippo compared the diets and gut microbiota of rural African children with those of European children. The European children had diets which were far more processed and western in style and contained less fibre and fewer unrefined plant foods. The African children ate a largely unrefined plant based diet.
The composition of the microflora living inside their guts was also markedly different. The African children had a greater variety of types of bacteria, and of these many were the ones beneficial to health as they were anti-inflammatory. European children had fewer species, and less bacteria overall. The link between diet and the resulting gut flora was quite clear to see.
More evidence of this relationship can be seen when the composition of the gut flora is observed before and after a change in diet. One 2013 study by Lawrence assigned ten people to either a plant based diet or an animal based diet and then looked at the changes. The gut flora changed quite markedly in only five days! In another experiment, a group of rural African and a group of African Americans were asked to swap diets and then the markers of bowel cancer risk within the bowel were measured. Both groups experienced changes, with the Africans’ markers worsening after being on their modern American diet and the African Americans seeing improvements.
So, the pointers are there to convince us that what we eat seriously impacts both our gut microbiota and in turn our health. And it’s not just physical chronic disease which is affected, but mental health too is mediated by the composition of the gut flora. The Food and Mood Centre at Deakin University has done some fascinating research into this.
How then can we eat better to keep the gut flora well fed and in sufficient numbers to have a positive impact on our health?
Firstly, research is moving fast. At the moment we know that everyone has a unique colony of microbes and no- one knows what an ‘ideal’ set of them looks like. It is likely slightly different for everyone. However, we do have some good indicators of which types of bacteria produce metabolites (products made by them when they ‘eat’ our food) which are anti-inflammatory; and which bacteria are commonly found in high numbers in very healthy people or conversely in people with poor health. Thus, we have some guidelines.
The gut-friendly diet is based on:
· A wide variety of vegetables and fruits. (Because they contain fibre and polyphenols).
· Fermented foods such as yoghurt, kefir, sauerkraut, tempeh and kim chi. (Because the fermentation process involves bacteria and these pass into your system when you eat the fermented food). Interestingly, the benefit seems to remain even when stomach acid kills the bacteria during digestion!
· Whole grains – unrefined grains such as wholemeal flour, barley, oats, quinoa, psyllium, freekeh and others contain plenty of undigestible (for us) fibre which is ideal ‘food’ for the gut microbes to munch on.
· Vegetables and fortified foods containing inulin. These include leeks, garlic and Jerusalem artichokes. Inulin is also used a food processing aid so can be found in some yoghurts and other foods.
· Fortified foods containing live bacteria (known as probiotics). These have become much more common recently. However, a diet based on unprocessed healthy foods is better than eating a processed food with added bacteria!
· Some starchy foods which have been cooked and then cooled actually change their structure and become more difficult to digest, thus providing undigested fibre for gut microbes to eat. Cooked and cooled potatoes, rice, pasta and also under ripe bananas are good examples of resistant starch.
Of course, a whole lifestyle approach is the best way to have a positive influence on your gut microbiota, so along with your new improved diet, have a look at some other areas of your life:
· Getting enough quality sleep
· Managing stress
· Avoiding non-essential antibiotic use (and using a probiotic after a course of antibiotics to get you back on track)
· Staying active - whether in organised exercise or activities such as gardening, walking to work or dancing your way through the housework - they all count!
· Getting outside in nature
This sounds like a lot to address! If you need support in making the transition to a more gut friendly diet and way of life, get in touch!
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