By Dr Tim Crowe

You are what you eat. It is a common saying, but when it comes to your health, especially your gut health, what you eat has a profound impact on keeping you and your gut microbes in good shape. And with 100 trillion bacteria in your gut, that’s a lot of mouths to feed.

The importance of prebiotics

The bacteria in our gut play an important part in our health and it is prebiotics that is the food that they thrive on. Prebiotics act as a fuel to promote the growth of beneficial bacteria such as Bifidobacteria and Lactobacillus. So, think of prebiotic food as like fertilizer for your gut.

Health benefits of prebiotics include enhancing gut barrier function, improving the bioavailability of calcium and magnesium, boosting immunity, and even keeping bowel movements regular. Prebiotics can also help reduce the amount of potentially damaging bacteria in the gut by altering the pH, making it less of a hospitable place for more harmful bacteria.

Sources of prebiotics

To keep your gut ecosystem thriving, aim to eat more foods high in different types of fiber including soluble and insoluble fiber and resistant starch. Fiber is nourishment for good gut bacteria, and you will find it an array of everyday foods. The simplest advice is to eat a wide variety of nutritious whole foods from all food groups, which would naturally contain different types of fiber.

Some of the key prebiotic foods include:

  • Aromatic vegetables such as onions, garlic, leeks, celery, and Jerusalem artichokes. These are high in a type of carbohydrate called insulin which bacteria use to promote healthy colon cells and other health benefits
  • Barley and oats are a rich source of soluble fiber, beta-glucan. Beta-glucan acts as food for your good gut bacteria and helps lower cholesterol levels
  • Starchy foods such as cooked potatoes, beans and lentils and green bananas are a great fuel source for gut bacteria
  • Fermented foods such as sauerkraut, kimchi, kefir, and yogurt contain a good supply of healthy bacteria to add to your gut bacterial community

While researchers have yet to work out what the ‘perfect’ diet may be for gut health, we know that the worst way of eating for your digestive health is having a diet with too many highly processed foods, too much sugar and not enough fiber.

The good news is that a shift to a healthier diet can change the bacteria mix in a few short days. To do this, approach it as a long-term game where you make small changes and healthy food swaps over many weeks to months to make the changes sustainable. Something as simple as eating two pieces of fruit each day and choosing wholegrain foods over more refined grains is a great way to start. Then look at adding in more of the variety of prebiotic foods available to us.Reference: Carlson JL et al. Health effects and sources of prebiotic dietary fiber. Current Developments in Nutrition 2018;2:nzy005.