What is fibre and what does it do?
Dietary fibre is not considered a macro-nutrient but is a sub-type of carbohydrate. Fibre reaches our colon undigested by our digestive enzymes. There are two types of dietary fibre, soluble and insoluble.
Fibres that dissolve in hot water are soluble, and those that do not are insoluble. Soluble fibers can bind nutrients and water, form gels and can be fermented, while insoluble fibres can only bind water and be degraded.
Some of the fermentable fibres are prebiotics which help with the growth of useful bacteria in the gut. They can also help make short-chain fatty acids which aid in water and sodium absorption throughout the gut. Non fermentable fibres are useful in the colon too as they move through virtually unchanged helping to keep your bowel movements regular, with adequate shape and volume and take any old rubbish in your gut along with them and out of the system.
In summary, intaking some dietary fibre is super helpful for a gut that functions at it’s best.
I don’t like the phrase ‘gut health’ as we can’t define that, but if there was ever ‘one weird trick to supercharge your gut health’ intaking adequate fibre would be it.
Notable health benefits of fibre:
There are a number of well studied health outcomes associated with intaking adequate dietary fibre.
Lowered risk of heart disease and coronary heart disease.
Lowered LDL cholesterol.
Lowered risk of metabolic syndrome.
Decreased risk of developing Type 2 Diabetes.
Decreased risk of developing colorectal cancers.
Higher dietary fibre intake requires a diet to contain a certain amount of whole grains, fruits and vegetables.
Higher fibre diets are satiating, which can be particularly useful when utilising caloric restriction.
Fibre has a thermogenic effect on the body, again useful during a weight loss or weight maintenance phase.
Calories in Fibre
There are two common beliefs about fibre calories that you may hear thrown around:
Fibre is a carb so should be counted/ tracked as 4kcal per gram.
Fibre doesn’t get digested at all so it doesn’t contain any calories.
Both of these are incorrect. The answer, like most things, lies somewhere in the middle. Most experts tend to agree that fibre is around 1.5-2kcal per gram for most types of soluble fibre.
I personally do not think that it’s worth counting the calories from dietary fibre unless in very extreme dietary situations. If you track macros using an app the app will handle this stuff for you.
What about fibre supplements?
I personally do not think fibre supplements are necessary for the average health conscious individual. Supplements and fibre bars are usually not very nutrient dense and can be calorific. They may help to increase a person’s overall fibre intake but if there are still very few vitamins and minerals coming into the diet it’s not a hugely helpful intervention.
A simpler solution would be to eat adequate fibrous fruits, vegetables, legumes and wholegrains. These come with a range of nutrients in addition to fibre so overall pack more of a punch for health than fibre supplements alone do.
So how much fibre should I eat?
At the time of writing, there no globally accepted optimal intake for fibre.
The average adult in the US eats around 12–18 grams of fibre per day which is lower than what I would class as ideal.
Some recommendations I pulled of the web:
American Dietetic Association: 20g-38g daily or 14g per 1000kcal.
The Institute of Medicine: 38g for men and 25g for women, daily.
American Heart Association: 25g-30g daily.
Age is a factor here too as children and the elderly consume less fibre.
The average recommendation here looks to be around 20-40g per day for adults.
Generally speaking I feel 25-35g per day for females and 30-45g per day for males is an appropriate range for fibre intake. Where a person sits in that range or if more of less fibre could be called for would be dependent on total caloric intake.
I don’t believe any issues would arise from eating more than 45g of fibre per day however perhaps above 60g per day may be overkill and potentially could have an adverse effect on bowel movements.
If you are new to a fibre intake in that range and want to begin aiming for it then I would suggest titrating fibre intake up slowly overtime rather than making any sudden increases. Doing so may help with avoiding possible discomfort, bloating, gas or erratic stool output.
So what should I eat?
Because I’m nice I put together this list for you. Feel free to copy & paste and stick it on your fridge. I'm sure you can find some things in there that you enjoy and can work easily into your diet. You got this.
High Fibre Foods
Sweet potato 4 Grams Per 1 Small Sweet Potato
Sun-Dried Tomatoes 3.5 Grams Per 1/2 Cup
Brussels Sprouts 3 Grams Per 1 Cup
Almonds 3 Grams Per 1 Ounce
Sunflower Seeds 3 Grams Per 1 Ounce
Pistachios 3 Grams Per 1 Ounce
Acorn Squash 9 Grams Per 1 Cup, Cooked
Butternut Squash 1 cup: 6.6g
Artichoke 7 Grams Per 1 Medium Artichoke
Parsnips 7 Grams Per 1 Cup
Broccoli 1 cup: 5.1 grams
Dried Coconut 5 Grams Per 1 Ounce
Ground Flaxseed 4 Grams Per 2 Tablespoons
Chia Seeds 11 Grams Per 1 Ounce
Kumquats 5 Grams Per 5 Fruits
Dates 6 Grams Per 1/2 Cup
Pears 6 Grams Per 1 Medium Fruit
Avocado 6.5 Grams Per 1/2 Avocado
Blackberries 8 Grams Per 1 Cup
Rasberries 8 Grams Per 1 Cup
Dried Figs 15 Grams Per 1 Cup
Popcorn 4 Grams Per 4 Cups
Steel-Cut Oats 5 Grams Per 1/4 Cup, Dry
Wheat Bran 6 Grams Per 1/4 Cup
Bran Flakes ¾ cup: 5 grams
Lima Beans, Frozen 5 Grams Per 1/2 Cup
Refried Beans 7 Grams Per 1/2 Cup
Edamame 8 Grams Per 1/2 Cup
Black Beans 8.5 Grams Per 1/2 Cup
Chickpeas 11 Grams Per 1 Cup
Split Peas 13 Grams Per 1/4-Cup
Kidney Beans 14 Grams Per 1 Cup
Lentils 15 Grams Per 1/4 Cup
Navy Beans ½ cup: 9.6 grams
Collard Greens 1 cup: 7.6 grams
Green Peas 1 cup: 7.2 grams
Pomegranate Seeds ½ pomegranate: 5.6 grams
Whole Grain Bread per slice: 4-5 grams
Whole Grain Pasta 1 cup 6.8 grams, spaghetti
Apple medium apple (with skin): 4.4 grams
Russet Potato 1 medium potato (with skin): 4g
Cocoa Powder 2 Tbsp (unsweetened): 4 grams
Carrots 1 cup (raw): 3.6 grams
Banana medium banana: 3.1 grams
Average fibre intake in the US:
IOM fibre rec.
American Dietetic Association fibre rec.