Foods that feed your gut microbiome - Food for the Brain

Foods that feed your gut microbiome

Did you know that up to 2kg of your body weight is bacteria? The average person has about 130 different types of friendly bacteria, mainly resident in the digestive tract, and they are forever multiplying. There are about 100 trillion bacteria in your digestive tract, most of which are in the colon. That’s about ten times the total number of cells in your body, with a combined weight twice that of your brain. Every day you make quantities of bacteria and eliminate an equal amount in stools.

Not all of these bacteria are good for you, but, provided you have enough of the health-promoting bacteria, they act as your first line of defence against unfriendly bacteria and other disease- producing microbes, including viruses and fungi.

The good bacteria make some vitamins and digest fibre, allowing you to derive more nutrients from otherwise indigestible food, and also help to promote a healthy digestive environment. It is not just the quality but also the quantity of bacteria that makes a difference to your health.

We are, in fact, partly descended from bacteria. Within our body cells are organelles (or components), each with a specific function. Biologists now believe that the complex cells that make up our bodies may have developed from smaller microorganisms, such as bacteria, working together. Over time, this cooperation led to the development of the complex cells from which we are made; for example, the energy factories within our cells (called mitochondria) are derived from bacteria.

Like our fingerprints, our microbiome (the specific family of microorganisms found in our gut) is unique to each one of us and is comprised of a balance of different bacteria, some better for us than others. What exactly makes up a healthy microbiome is the subject of much research.

Some kinds of starch or carbohydrate are difficult to digest and act as fibre. These ‘resistant’ starches also feed gut bacteria and are thus called prebiotics because they can help healthy bacteria in the gut to grow. A classic prebiotic is FOS (fructo- oligosaccharides), which you might have seen in the list of ingredients of probiotic supplements. They are included to feed the bacteria when they hit fluids in your digestive tract. Another is inulin (containing fructans), derived from chicory root. Oats contains glucans, a similar molecule. Having a diet high in resistant starch is a good idea, and there are two ways to do this. The first is to eat foods that are naturally high in it.


These include:

  • Jerusalem artichokes
  • Garlic, leeks and onions – in that order
  • Asparagus
  • Cashew nuts
  • Oats, uncooked
  • Chicory
  • Green bananas, raw
  • Peas, beans and lentils

The second way to increase your intake of resistant starch is to cook a carb and cool it, then to eat it cold or reheated. Oats naturally have ten times more resistant starch raw than cooked, but if you make porridge and cool it, you recreate resistant starch. Or take a small cup of oats and mix with a dessertspoon of chia seeds and some plant milk and leave it to soak overnight for an oat & chia porridge, topped with berries and yoghurt.

The same is true with potatoes, rice and pasta. If you steam new potatoes, then cool them, to make a potato salad, you significantly increase the level of resistant starch. You can do the same thing with rice and pasta, but its best to start with a long- grain brown rice or wholegrain pasta, which is naturally high in resistant starch; for example, you could make a pasta salad or a cold rice pudding using dried Montmorency cherries instead of raisins, and oat milk instead of cow’s milk, if you are dairy sensitive.

Even though the sugar in bananas is fast- releasing, hence they are high GL, the same is not true for a green banana eaten raw. Cut a green banana into thirds then put a third, plus some frozen blueberries, in your breakfast smoothie mix in the morning.