The gut is one of the largest, most dynamic, yet undervalued, organs in the human body. Dietary fibre is one of the best ways to maintain good-gut-health.

What is fibre?

Fibre is found in plant-based foods such as fresh fruit, vegetables, legumes, and wholegrains, and is the part of the plant that cannot be broken down by the digestive enzymes in the gut. Our gut needs different types of fibre to keep it healthy.

  • Soluble fibre acts like a mop and helps absorb fluid in the gut, forming a soft, gel-like “mush” that helps passage through the gut. This fibre is found in rolled oats, oat bran, oranges, bananas, apples, carrots, berries, and legumes such as beans, lentils and split peas.
  • The other type of fibre is insoluble fibre, also referred to as roughage. This type of fibre does not dissolve in water. Insoluble fibre acts like a broom, roughly sweeping through the length of the gut to remove waste. This type of fibre is found naturally in wholegrains such as wholegrain bread, whole-wheat pasta, oats, bran, corn, brown/wild rice, nuts, seeds, and the skin of fresh produce.

What are the health benefits of fibre?

Fibre does far more than just keep us regular: it is involved in a wide range of health benefits. Cholesterol-lowering benefits are seen when soluble fibre dissolves, binding cholesterol that is then removed by the gut. Foods rich in fibre tend to be low in energy too, assisting with weight loss. Furthermore, fibre-rich foods are naturally nutrient-rich too such as fruit and vegetables, boosting our nutrient intake for an overall healthier diet. Diets low in fibre tend to be higher in meat and fat which can cause enzymes in the colon to breakdown cancer-causing carcinogens. For this reason, the South African food-based dietary guidelines recommend that we eat at least five portions (400g) of a variety of fruit and vegetables each day to help meet our fibre needs, along with other fibre-rich foods.

The glycaemic index or GI is a measure of how quickly a carbohydrate is broken down and absorbed by the body. For good health, we should choose foods that are mostly low GI (below 55) and only use high GI foods (above 70) during exercise. There are a range of factors that influence the GI. One factor is the amount of fibre in the food, which is why most fibre-rich foods are naturally low GI. There is a lot of evidence to show that a low GI diet (because of the fibre) may lower the risk of type 2 diabetes, heart disease, and cancer, as well as have cholesterol-lowering benefits. For the weight conscious, a high fibre/low GI diet may keep hunger and cravings at bay by controlling blood sugar dips, and because of fibre’s bulking action in the gut, you will feel fuller for longer, too.

It is not widely known that fibre can help our immunity, too. This is because 65% of our immunity is found in our gut. The gut is home to 40 trillion microorganisms which shows the huge responsibility that fibre plays in optimal health and wellbeing. Fibre helps create a good environment for the growth of the friendly microorganisms that make a home in our gut. These microorganisms can be bacteria (e.g. lactobacilli or bifidobacteria) to yeasts (e.g. Saccharomyces boulardii) and are found naturally in fermented foods like yoghurt and maas/amasi, or can be taken as a supplement. When eaten, these microorganisms pass through the gut and multiply to live along the length of the gut. Fibre is called a prebiotic because it acts as a source of food for these healthy microorganisms to grow and thrive. Prebiotics are found in bananas, onions, garlic, oats, and barley.

How can I choose more high fibre foods?

Many South Africans fall short of their recommended fibre intake each day. It is recommended that women consume at least 25g of fibre per day and men at least 38g of fibre. A 2015 study that surveyed the diets of South African adults showed that fibre intake in women and men could be as low at 16g and 18g, respectively. Reading food labels is a great tool to help improve your nutrient and fibre intake. According to South African food label guidelines, for a product to be considered high in fibre it needs to contain more than 6g of fibre per 100g of the product. Look out for products high in fibre by learning to read food labels.

Fibre clearly plays a key role in optimizing the health of the complex gut ecosystem. It is important to note that a diet rich in fibre from fruit and vegetables would naturally be rich in healthy nutrients such as vitamins, minerals, antioxidants and phytonutrients, making it a win-win situation to choose high fibre, nutrient-rich foods as part of your daily diet.

Written by Monique Piderit, RD (SA)