Dietary fibre is a widely used term. It’s commonly associated with many health benefits, but do we know what fibre is exactly?

Well, “dietary fibre” is an umbrella term for any undigestible carbohydrate that reaches the large intestine. Here it will be fully or partly broken down into gases (primarily hydrogen gas) and short chain fatty acids (SCFAs) by the bacteria in our gut.

Sometimes you hear the terms “soluble” and “insoluble” fibre. Have you ever wondered what the difference is?

Soluble vs Insoluble fibre infographic

Soluble fibre

This type of fibre retains water. It forms a gel-like material during digestion. It tends to slow down digestion and helps with the absorption of nutrients.

Some key health benefits of soluble fibre include:

  • Helps eliminate cholesterol from the body. It lowers LDL cholesterol (the bad one), which in the long run can protect against heart disease
  • Helps to stabilise blood sugar levels as it slows down the digestion of foods, including carbohydrates. This helps prevent spikes in blood sugar levels
  • Acts as food for our gut microbes, promoting the growth of good bacteria
  • Weight management. Because it slows down the digestion of food, it can leave us feeling fuller for longer

Foods naturally high in soluble fibre

  • Vegetables: broccoli, brussels sprouts, avocado and peas
  • Fruits: Apples, strawberries
  • Legumes: lentils, black beans
  • Grains: flaxseed, barley, chia and oats
White AIRE on top of red lentils and black beans

Insoluble fibre

This type of fibre doesn’t retain any water. It remains fairly intact as it travels through your digestive system. It tends to speed up the passage of food through the stomach and intestines. It also has a bulking effect by increasing the size of the stool.

Some key health benefits of insoluble fibre include:

  • Helps with the passage of food. This reduces the incidence of constipation
  • Helps reduce the risk of haemorrhoids (piles)
  • Acts as food for our gut microbes, promoting the growth of good bacteria
  • It can help reduce the incidence of diverticulitis (inflammation in the intestines)
  • It can keep us feeling fuller for longer

Foods naturally high in insoluble fibre:

  • Wholegrain foods: wheat bran, brown rice and couscous
  • Cereals: bran flakes
  • Root vegetables: carrots, parsnips and potatoes
  • Vegetables: celery, cucumber, broccoli, brussels sprouts and courgette
  • Fruits: bananas, orange, pear and blackberries
  • Legumes: beans, pulses and lentils
  • Nuts: almonds, brazil nuts

So, fill up on fibre!

However, it’s important to always be mindful of portion sizes. This is especially important if you have a sensitive gut. If you’re thinking of increasing your fibre intake, start small and track how you’re feeling as you introduce different types of fibre. Many fibre-rich fruits and vegetables contain FODMAPs. If you’re sensitive to FODMAPs, use your FoodMarble AIRE app to check the FODMAP content of different foods. Many plant foods contain both soluble and insoluble fibre to varying degrees. To receive the greatest health benefits, try eating a wide variety of fibre-containing plant-foods.

I’ve written about the importance of fibre before. Check out my other blogs to learn more:

Fibre, Fermentation & FODMAPs – The New F Words!

How fibre helps protect your gut health

High carb vs. high protein: the good, the bad & the ugly


FoodMarble AIRE is the world’s first personal hydrogen breath tester. It is a pocket-sized breath analysis device. It helps people with chronic digestive issues determine the foods that work best with their digestive system. To learn more about FoodMarble, visit or follow us on