Fiber intake is associated with numerous health benefits. However, most people in North America consume far less than the daily recommended intake levels. Fiber may be my favorite nutrient. I love helping people increase fiber intake because it's one nutrient where they often feel the effects (hopefully in a good way!).
- What is Fiber?
- What Fiber Does in the Body
- Daily Intake Requirements of Fiber
- How to Consume Enough Fiber
- Vegan Food Sources of Fiber
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What is Fiber?
Fiber refers to a group of carbohydrate compounds that are not broken down by the body 1. Instead, they either pass through the intestinal tract untouched or are digested by the good bacteria that live in the intestinal tract 1.
There are many different types of fiber found in foods and several ways to classify types of fiber.
The most common classification method for fiber is whether the fiber mixes with water or not.
With this type of classification system, the two main types of fiber are:
- Soluble fiber: Soluble fiber mixes with water and creates a gel in the intestinal tract. The gel that is created is very similar to what happens when you make a chia seed pudding or a flaxseed “egg”.
- Insoluble fiber: Insoluble fiber does not mix with water. This type of fiber typically moves through the digestive tract unchanged and is often considered a good “bulking” agent (for increasing stool size).
The types of fiber could also be classified based on whether it is digested (aka fermented) by gut bacteria or not.
Additionally, there’s a type of carbohydrate called resistant starch. Most starch found in food is digested by humans however there are some starch molecules that are not digestible. These are called resistant starches (resistant to digestion) 1.
What Fiber Does in the Body
The primary role of fiber is to provide bulk to stool. Since much of the fiber we eat is left intact, it moves through us whole and creates the bulk of our stool (stool = poop). This bulk helps keep things moving through the digestive tract which can be very beneficial for health. In this way, fiber intake could also help with constipation.
Fiber also helps keep us feeling full, literally. Fiber physically keeps our intestines full since it isn’t broken down.
Another important role of fiber is to “feed” the healthy gut bacteria we have. Most gut bacteria lives in the large intestine. By the time food gets down into the large intestine, it’s mostly digested and absorbed so there isn’t much left beside the fiber (which isn’t digested or absorbed). This fiber then becomes food for the healthy gut bacteria. When bacteria break down fiber, it creates short chain fatty acids which may also play an important and positive role in health.
Increased fiber intake has been associated with decreased risk for:
Fiber intake may also be helpful in the treatment of the above conditions and:
If you have any of these conditions, you need to be under the supervision and care of a medical doctor/ team. Always speak to a doctor before making any changes to your diet.
Daily Intake Requirements of Fiber
The Canadian recommendations for fiber intake are: 29
- 38 grams per day for men age 19-50
- 30 grams per day for men age 51 and over
- 25 grams per day for women age 19-50 (pregnant and breastfeeding women have separate recommendations)
- 21 grams per day for women age 51 and over
Overall, Canadians do not meet these recommended daily intakes. In fact, most Canadians only get half their recommended daily intake 29.
On the other hand, someone following a mostly whole food plant-based diet could get double this recommended amount on a regular basis! While more is not always better, the foods that contain fiber also provide other health benefits so additional intake could be a good idea for many people (not everyone benefits from increased fiber – always talk to your doctor before making changes to your diet and work with a dietitian to implement appropriate dietary changes).
How to Consume Enough Fiber
As with any lifestyle change, it can be challenging for people to increase the amount of fiber they eat. The best way to succeed with lifestyle changes is to set SMART goals. These are goals that are specific, measurable, achievable, relevant and time-bound.
For example, setting a goal like “I will increase my intake of fiber” does not meet any of the above SMART criteria. Instead, aim to set a goal more like “For the next 2 weeks I will add one serving of a high fiber food to my breakfast meals”. This goal is much more specific, measurable (“one serving”), likely more achievable and time-bound (“2 weeks”). You could take this goal a step further by specifying the high fiber food(s) you would include.
Setting smaller goals can help you achieve them because they’re more realistic. Beyond being more realistic, when working towards increasing fiber intake, going slowly can be important.
Fiber intake can help with digestive health, however some people may notice “side effects” when they start to increase their intake of fiber. The most noted symptoms seem to be bloating, gas and general abdominal discomfort. While these symptoms can certainly happen with increased fiber intake, research shows that humans can tolerate high levels of fiber without any long-term health impacts 30.
Nevertheless, it’s generally recommended to slowly increase fiber intake over time to reduce the chance of any negative “side effects” 29.
It’s also extremely helpful to consume enough fluids when increasing fiber intake. Water and other fluids can help keep masses moving properly in the digestive tract and help with the transition to higher fiber intake.
Vegan Food Sources of Fiber
Unless a vegan food has undergone a process to remove all the fiber, most vegan foods contain at least a little bit of fiber. All whole plant-based foods contain fiber so if these are included in the diet, it’s quite possible to meet (or exceed) intake recommendations.
If you are looking to increase fiber intake, it’s helpful to know what foods are highest in fiber. Whole grains, legumes, nuts and seeds do vary in their fiber content but there is less variation compared to the fruits and vegetables.
With fruits and vegetables, there is more variation in fiber content so to help out, here are lists of high fiber vegetables and fruits.
Higher fiber vegetables include: 29
- Sweet potato
- Green peas
- Collard greens
- Snap peas
- Brussels sprouts
Higher fiber fruits include:
- Berries, including cherries
- Pear (with the skin)
- Stone fruits (plums, peaches, nectarines, apricots)
All other vegetables and fruits contain fiber, to varying levels. They are also healthy to include in the diet. For most people, setting any goal to increase vegetables and fruits is a great place to start but if you enjoy any of the foods on these lists then selecting them could increase overall fiber intake.
Summary: Fiber for Vegans
Fiber is an important but often overlooked nutrient. Fiber has many roles in the body and increased fiber intake is associated with decreased risk of many diseases. Intake of fiber may also be helpful to treat certain conditions (always speak to your doctor before making any changes to your diet). It can be quite possible to meet or exceed fiber intake recommendations on a plant-based diet, as long as some emphasis is placed on consuming whole plant-based foods.
Working with a dietitian can be an excellent choice for achieving nutrition goals for long-term health.
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- Dietary fiber
- Associations of Dietary Fiber Intake With Long-Term Predicted Cardiovascular Disease Risk and C-Reactive Protein Levels (from the National Health and Nutrition Examination Survey Data [2005e2010])
- Dietary fiber intake and risk of cardiovascular disease: systematic review and meta-analysis
- Lower lifetime dietary fiber intake is associated with carotid artery stiffness: the Amsterdam Growth and Health Longitudinal Study
- Association between dietary fiber intake and fruit, vegetable or whole-grain consumption and the risk of CVD: results from the PREvención con DIeta MEDiterránea (PREDIMED) trial
- Consumption of cereal fiber, mixtures of whole grains and bran, and whole grains and risk reduction in type 2 diabetes, obesity, and cardiovascular disease
- Dietary fiber intake modifies the association between secondhand smoke exposure and coronary heart disease mortality among Chinese non-smokers in Singapore
- Effects of dietary fiber type on blood pressure: a systematic review and meta-analysis of randomized controlled trials of healthy individuals
- Dietary Fiber and Blood Pressure A Meta-analysis of Randomized Placebo-Controlled Trials
- Total, insoluble and soluble dietary fiber intake in relation to blood pressure: the INTERMAP Study
- Effect of a Very–High-Fiber Vegetable, Fruit, and Nut Diet on Serum Lipids and Colonic Function
- Lipid Lowering with Soluble Dietary Fiber
- High dietary fiber intake prevents stroke at a population level
- Fiber intake and glycemic control in patients with type 2 diabetes mellitus: a systematic review with meta-analysis of randomized controlled trials
- Higher intake of fruits, vegetables or their fiber reduces the risk of type 2 diabetes: A meta-analysis
- Dietary fiber, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies
- Dietary fiber intake and risk of breast cancer: A systematic review and meta-analysis of epidemiological studies
- Fiber intake modulates the association of alcohol intake with breast cancer
- Dietary fiber and the risk of precancerous lesions and cancer of the esophagus: a systematic review and meta-analysis
- Dietary fiber intake and head and neck cancer risk: A pooled analysis in the International Head and Neck Cancer Epidemiology consortium
- A Prospective Study of Long-term Intake of Dietary Fiber and Risk of Crohn’s Disease and Ulcerative Colitis
- Dietary fiber intake reduces risk of inflammatory bowel disease: result from a meta-analysis
- Dietary Fiber Intake and Total Mortality: A Meta-Analysis of Prospective Cohort Studies
- Fiber intake and all-cause mortality in the Prevencio´ n con Dieta Mediterra´ nea (PREDIMED) study
- Dietary Fiber and Telomere Length in 5674 U.S. Adults: An NHANES Study of Biological Aging
- Effect of fiber, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome: systematic review and meta-analysis
- Cereal fiber and whole-grain intake are associated with reduced progression of coronary-artery atherosclerosis in postmenopausal women with coronary artery disease
- High dietary fiber intake is associated with decreased inflammation and all-cause mortality in patients with chronic kidney disease
- Food Sources of Fiber
- High dietary fiber consumption is not associated with gastrointestinal discomfort in a diet intervention trial
Please note that this is a curated list of references for the topics above and is not intended to be comprehensive.
Disclaimer: always speak with a doctor before changing your diet. Please read our full website disclaimer.
Author Profile: Nicole Stevens
Nicole is a vegan Registered Dietitian (RD) and founder of Lettuce Veg Out. She provides vegans with balanced meals and easy-to-understand nutrition science.
Having attained a Masters degree and passing a national registration exam, Nicole is a trusted source of nutrition information. She uses this knowledge to educate others about vegan diets and how to thrive as a vegan.