Today I aim to help you answer the frequently asked question 'how much fibre should I eat' to lose weight and improve health?
Read on to learn everything you need to know about how much fibre to eat, what types of fibre are beneficial for health and weight loss goals, and the best types of food that contain beneficial fibre.
This guide takes a deep dive into dietary fibre, and all the benefits of getting it right, so let's dive right in!
Fibre is a complex carbohydrate made up of non-starch, polysaccharides, resistant starches and/or cellulose.
Dietary fibre used to be known as ‘roughage’, and refers to a group of substances in plant foods which humans do not possess the enzymes or digestive machinery to break down.
Previously it was considered that all fibre was completely indigestible and did not provide energy. Whilst this is technically true, we now know that some fibre types can be fermented in the large intestine by beneficial gut bacteria, which produce beneficial short-chain fatty acids (acetate, butyrate) and gases (methane, hydrogen and carbon dioxide).
It’s these short chain fatty acids that can be used as an energy source if they enter the blood stream.
What Is Dietary Fibre?
Over the last number of years, a lot of attention has been given to defining dietary fibre, however this has been a challenging and controversial issue.
This is because fibre cannot be defined as either a single chemical entity or a group of related compounds. Also, different fibre types may have one or more physiological functions or health benefits, which makes it difficult to define them by health outcomes. Lastly, it is fully known whether fibre has positive effects only when it is contained within the food matrix, or whether it also functions when isolated. This has made it very difficult for authorities to truly define fibre.
In 2009, the international CODEX alimentary agreed on the following definition, and this is now recognised across Europe:
Dietary fibre consists of one or more of:
- Edible carbohydrate polymers naturally occurring in the food as consumed;
- Carbohydrate polymers that have been obtained from food raw material by physical, enzymatic or chemical means and which have a beneficial physiological effect demonstrated by generally accepted scientific evidence;
- Synthetic carbohydrate polymers which have a beneficial physiological effect demonstrated by generally accepted scientific evidence.
To summarize this, any edible carbohydrate polymers that occur naturally in foods should have evidence of a beneficial physiological effect, and this needs to be supported by generally accepted scientific evidence.
Up until this definition was created and accepted, the UK definition had been expressed as any non-starch polysaccharides (NSP’s). NSP’s are classified as the cell wall compartments of plants and include cellulose, hemicelluloses, pectins, lignin, gums, and beta glucagon.
The updated definition by CODEX highlights that there are often compounds that are not digested nor classified within the human tract. This therefore includes resistant starches, oligosaccharides and some micronutrients.
Many UK food authorities still use NSP’s as a measure of dietary fibre.
What Are The Types Of Fibre?
For many years, fiber was essentially separated into two classes, soluble and insoluble, both of which possess different nutritional benefits. However, recently, these have been replaced with the terms viscous and non-viscous. For simplicity, we will stick with soluble and insoluble fiber in this article.
SOLUBLE FIBRE (CAN DISSOLVE IN WATER)
This fibre type is very resistant to being broken down by the digestive enzymes in our mouth, stomach and small intestine. It is therefore partially digested in the large intestine, where good bacteria ferment it, producing butyric acid (found in butter) and acetic acid (found in vinegar). This helps the digestive system maintain its acidity and good health. (1) (2) (3)
The following types of fibre fall into this category:
- Gums – are added to foods to help add texture and extend shelf life. Most importantly, they also slow down the absorption of glucose.
- Pectins – are slightly acidic and aid in the absorption of certain minerals like zinc.
- Inulin – is a prebiotic that feeds good bacteria in the stomach.
THE BENEFITS OF SOLUBLE FIBRE:
- Reduced risk of cancer - Fibre helps remove any build up of cancer-producing compounds. As fibre is fermented into short chain fatty acids, this helps the colon maintain its pathogen killing acidity.
- Lower LDL levels - As fibre is fermented into short chain fatty acids, this process also appears to result in a decrease in LDL (the bad) cholesterol levels. (4) (5) (6)
- Stable blood sugar - Soluble fibre slows down the digestion time of foods, particularly starchy carbohydrates, thus reducing the release of glucose into the bloodstream. Dietary fibre has also been shown to improve glycemic control which has an important role in managing diabetes. (7) (8) (9)
INSOLUBLE FIBRE
This is the most resistant fibre to digestion and is therefore passed through the digestive system intact. Its main role is to simply aid transport of other foods and liquids.
It does this by absorbing water and thus adding ‘bulk’ to our stools, making our faeces move faster through the intestines.
These types of fibre are typically lignin, cellulose or hemicellulose.
The benefits of insoluble fibre:
- Less constipation - Insoluble fibre can support regular bowel movements, as it reduces transit time in the digestive tract. (10)
- Reduced risk of cancer and bowel disease - By supporting regular bowel movement, it means the beneficial bacteria out number the harmful bacteria in our digestive tract. If this is not the case, putrefaction occurs, meaning toxic substances can build up and be reabsorbed in the body. This has been linked to bowel disease and certain cancers. (1) (2) (3)
Healthy Sources Of Fibre
Not only do we need to know how much fibre to eat in order to lose weight, improve health and generally be fit and health, we also need to consider the best types of fibre to eat,
It’s important to eat a wide variety of fibre containing foods, as the various components of dietary fibre are found in different proportions in different foods.
Below you will find a table that breaks down the various fibres into their components, further explanations and their ideal food sources.
This is in line with the CODEX definition and therefore includes resistant starch, oligosaccharides and micro components:
FIBRE COMPONENT | DESCRIPTION | FOOD SOURCES |
|---|---|---|
Cellulose | Polysaccharides comprising up to 10,000 closely packed units arranged linearly. | Grains, vegetables, fruit, |
Hemicellulose | Polysaccharides containing sugars other than glucose. | Cereal grains, vegetables, |
Lignin | A non-carbohydrate component associated with plant walls. | Foods with woody component, for example, celery and the outer |
Beta-glucans | Glucose polymers that (unlike cellulose) have a branched structure. | Mainly found in cell wall of oats and barley. |
Pectins | A non-starch polysaccharide common to all cell walls. | Fruits & vegetables, legumes, nuts & potatoes. |
Gums & Mucilages | Non-starch polysaccharides which | Gums: Seeds and seaweed Mucilages: pysillium |
Resistant starch | Starch and the products of | Legumes, potatoes, |
Oligosaccharides | Short chain carbohy- | Onions, chicory, |
Micro Components | Micro components of the | Cereal grains |
How Much Fibre Should I Eat For General Health?
The recommended average daily intake for fibre is at least 18g for adults and proportionally less for children.
Most people are not eating enough dietary fibre. The National Diet and Nutrition Survey reported that 72% of men and 87% of women were not meeting the recommended 18g of NSP’s per day.
They suggested that the average intake was 15g for men and 13g for women per day.
How To Measure Dietary Fibre Content?
The UK food industry uses the Englyst method for determining the amount of fibre in a food. This method measures plant cell wall components of dietary fibre, referred to as non-starch polysaccharides (NSP’s).
Other European and American countries use the American Association of Analytical Chemists (AOAC) method, which not only includes NSP’s, but lignin and resistant starches too. Due to the additional categories, the recommended daily intake of fibre when using the AOAC is 24g.
There are current discussions at the European level to decide on the most appropriate methodology to ensure that the definition is applied consistently in the labeling of foods.
European regulations on nutrition and health claims state that, for a product to be ‘source’ of fibre, it should contain at least 3g of fibre per 100g or at least 1.5g per 100kcal.
A product claiming to be ‘high in fibre’ should contain at least 6g of fibre per 100g or at least 3g of fibre per 100kcal. (12)
Summary Of Fibre
You now know how much fibre to eat to be healthy and to lose weight as well as the best types of fibre to eat, and the best foods that contain fibre.
Fibre is an important part of our diets, and we know high fibre foods tend to be healthier than the low-fibre alternatives.
Although we can see the benefits of including fibre in our diets, focusing specifically on the daily-recommended intake may not be required if eating a diet based around whole unprocessed foods. Reaching your daily needs for fruits and vegetables, adding in regular intake of legume will ensure you get plenty of fibre.
In the end, if you're eating a balanced diet that is composed mainly of whole foods with minimal processing, you probably don't need be be asking questions like ''how much fibre should I eat?''.
Instead, ask yourself ''how's this working for me?'' and make outcome based decisions until you achieve the desired outcome.
If you are struggling with your nutrition, and you're ready to accept help in this area of your life, you may be interested in my nutrition coaching service, or my online nutriton and fitness programme.
If you'd rather go it alone, and you're interested in reading around the dietary fibre topic, below are some references where you can learn more about how much fibre to eat for your specific health or weight loss goals.
Reference and Further Reading
- http://www.ncbi.nlm.nih.gov/pubmed/16633129
- http://www.ncbi.nlm.nih.gov/pubmed/16225487
- http://www.ncbi.nlm.nih.gov/pubmed/1612357
- http://www.ncbi.nlm.nih.gov/pubmed/7872224
- http://www.nejm.org/doi/pdf/10.1056/NEJM199307013290104
- http://www.ncbi.nlm.nih.gov/pubmed/23171573
- http://www.ncbi.nlm.nih.gov/pubmed/22555633
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621039/
- http://www.ncbi.nlm.nih.gov/pubmed/18287346
- http://onlinelibrary.wiley.com
- http://www.nutrition.org.uk/nutritionscience/nutrients/dietary-fibre?start=2
- Corrigendum to Regulation (EC) No 1924/2006 of the European Parliament and of the Council of 20 December 2006 on nutrition and health claims made on foods. Official Journal of the European Union, 18.1.2007.
- http://www.nutrition.org.uk/nutritionscience/nutrients/dietary-fibre?start=2