Fiber intake is associated with numerous health benefits. However, in North America, most people consume far less fiber than recommended. Vegan diets typically provide adequate fiber, but this may not always be the case.
This article explores the health benefits of fiber and provides tips on meeting recommended fiber intake levels on a vegan diet.
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What is Fiber?
Fiber is a type of carbohydrate that the body doesn’t break down 1. Instead, fiber either pass through the intestinal tract untouched or is digested by the good bacteria that live in the intestinal tract 1.
Fiber can be categorized in many ways, with the most common method being how fiber interacts with water. With this classification system, the two main types of fiber are:
- Soluble fiber: This type mixes with water, forming a gel in the intestinal tract; like a flaxseed “egg” or chia pudding.
- Insoluble fiber: Insoluble fiber does not mix with water. It moves through the digestive tract unchanged and is often considered a good “bulking” agent for increasing stool size.
Fiber can also be classified based on whether it is digested (fermented) by gut bacteria.
Additionally, there’s a type of carbohydrate called resistant starch. While most starch in food is digested by humans, some starch molecules are resistant to digestion and act like fiber instead 1.
What Fiber Does in the Body
Fiber’s primary function is to provide bulk to stool since much of the fiber we eat remains intact through the digestive tract. This bulk helps maintain the flow of contents through the digestive system and can be beneficial for health, including the prevention of constipation.
Fiber also promotes a feeling of fullness, literally. It resists digestion, keeping the intestines physically full.
Another important role of fiber is to “feed” the beneficial gut bacteria residing in the large intestine. By the time food reaches the large intestine, most of it has been digested and absorbed, leaving the untouched fiber. This fiber then becomes food for these beneficial gut bacteria.
When bacteria break down fiber, they create short chain fatty acids which are thought to have positive health effects.
Health Benefits of Fiber
Increased fiber intake has been associated with decreased risk for:
- Cardiovascular disease 2, 3, 4
- High blood pressure 5, 6
- High cholesterol 7, 8
- Stroke 9
- Type 2 diabetes 10, 11
- Colorectal cancer 12
- Breast cancer 13, 14
- Head and neck cancer 15, 16
- Crohn’s disease and ulcerative colitis 17, 18
- Total risk of mortality 19, 20, 21
If you have any of these conditions, it’s essential to be under the care of a medical doctor or team. Always speak to a doctor before making any changes to your diet.
Daily Intake Requirements of Fiber
The Canadian and US recommendations for fiber intake are: 24
- 38 grams per day for men aged 19-50
- 30 grams per day for men aged 51 and over
- 25 grams per day for women aged 19-50 (pregnant and breastfeeding women have separate recommendations)
- 21 grams per day for women aged 51 and over
The EFSA (European Food Safety Authority) recommends a daily intake of 25 grams per day for all adults 25.
Overall, most people do not meet these recommended daily intakes. In fact, most people only consume half the recommended daily intake and only 5% of Americans are found to meet recommendations 24.
How to Consume Enough Fiber
The most effective way to ensure adequate fiber intake is by increasing your consumption of whole, plant-based foods. Below is a list of high-fiber foods to incorporate into your vegan diet.
If you’re new to eating a higher-fiber diet, you may experience some “side effects”. While fiber is generally beneficial for digestive health, your body may require some time to adjust to larger amounts.
It’s best to increase fiber intake slowly, by adding one serving of high-fiber food per day, until the body adjusts. Afterward, you can consider adding more, as desired. Too much fiber all at once can lead to bloating, gas, abdominal discomfort, and possible issues like constipation or diarrhea 26.
When increasing fiber intake, it’s also important to consume enough fluids. Proper movement through the digestive system relies on water and other fluids. If you find yourself not drinking enough water during the day, make sure to increase water intake along with your fiber intake goals.
Do Vegans Need More Fiber?
Many vegans can easily meet recommended fiber intake levels. Some may wonder if vegans should consume even more fiber than current guidelines suggest.
To date, I haven’t found research that explores consuming fiber above the recommended intake amounts. Since most people (up to 95% of the US population) don’t meet the current requirements, there’s little incentive to research intakes above this amount.
Vegan diets can easily provide excess fiber, potentially exceeding double the recommended daily amounts. A typical day of baked oats for breakfast, pasta salad for lunch, a smoothie as a snack, and chili for dinner, can pack in over 50 grams of fiber.
So, vegans shouldn’t need to concern themselves about meeting fiber intake amounts, unless they primarily eat processed foods. Instead, they can enjoy the health benefits of fiber and focus on other nutrients that are more challenging to consume.
Drawbacks of Very High Fiber Diets
It’s challenging to determine the effects of excessive fiber intake, given the lack of research. High-fiber diets may not be suitable for individuals who struggle to consume sufficient calories during the day or those with specific medical conditions 27.
Since fiber is filling, someone who struggles with eating enough may want to select foods with higher calorie density, to meet nutritional and caloric needs without feeling overly full.
Some people who struggle with irritable bowel syndrome may also benefit from adjusting the amount or types of fiber in their diets.
Vegans should aim to meet all their nutritional needs. Occasionally, I’ve seen recommendations that promote very excessive fiber intake amounts, that aren’t needed or backed by research (as far as I can find).
For those who do eat large amounts of fiber, and who can tolerate it without digestive distress, there shouldn’t be concern with high intake levels 28. However, it’s important to prioritize meeting needs for all essential nutrients, of which fiber is only one.
Vegan Food Sources of Fiber
Most vegan foods contain some amount of fiber unless they have undergone a refining process to remove it. Whole plant-based foods are rich in fiber, making it possible to meet or exceed recommended intake levels on a vegan diet.
Additionally, higher fiber vegetables include:
- 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, increasing their consumption of vegetables and fruits is an excellent starting point, but incorporating items from these high-fiber lists can significantly boost overall fiber intake.
Summary: Fiber for Vegans
Fiber is an important nutrient with many roles in the body. 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).
Achieving or surpassing recommended fiber intake levels on a plant-based diet is entirely possible, and many vegans do not need to focus on meeting intake requirements for fiber. For those interested in eating more fiber, many high fiber vegetables, fruits, grains, legumes, nuts and seeds are available.
Always speak with a doctor before changing your diet or taking new supplements. Please read our full website disclaimer.
About Nicole Stevens
Nicole is a vegan Registered Dietitian (RD) and founder of Lettuce Veg Out.
She helps people thrive on a vegan diet with balanced recipes and easy-to-understand nutrition science.