These uncomfortable side effects of excessive fiber can occur when someone eats more than 70 grams (g) of fiber a day. This is not uncommon, and it may be more likely in a person following a vegan, whole food, or raw diet.
In this article, we look at how much fiber is too much and how to tell when you have eaten it in excess. Plus, we look at treatments, and the good sources of fiber to introduce into your diet.
How much is too much?
Although fiber is an important part of a healthy diet, eating too much fiber may cause problems.
Fiber is the indigestible part of plants and carbohydrates. Foods like lentils, vegetables, and cereals are high in fiber.
In general, eating too much fiber is a less common problem than eating too little. Only an estimated 5 percent of Americans meet their daily recommended fiber intake.
The optimal amount of fiber varies based on an individual's gender, age, and pregnancy status.
The Academy of Nutrition and Dietetics recommend the following for dietary fiber intake:
- 25 g per day for adult women
- 38 g per day for adult men
- less fiber after aged 50 years old (21 g for women, 30 g for men)
- more fiber when pregnant or lactating (at least 28 g per day)
However, eating more than 70 g of fiber a day can cause uncomfortable side effects, and some people may experience these after just 40 g.
When eating foods, such as high-fiber nutrition bars and fiber-added bread, eating 70 g of fiber in a day is not difficult.
A healthy diet of oatmeal for breakfast, a sandwich and fruit or vegetables for lunch, and a whole-grain dinner with lentils can easily reach that threshold.
Symptoms and side effects
The most common symptoms of eating too much fiber are:
- feeling too full
- stomach cramps
- constipation or diarrhea
- poor absorption of some key nutrients
- weight gain or loss
- intestinal blockage in rare cases
Fiber makes bowel movements bigger and bulkier. It also promotes fermentation and gas formation. This is why excessive fiber intake frequently affects the digestive system.
Fiber is vital for healthy, solid bowel movements. However, too much of it can cause constipation.
A 2012 study tested the effects of changing the fiber intake of 63 people who were experiencing constipation, bloating, and stomach pain.
In this study, individuals who reduced their fiber intake had more frequent bowel movements, less bloating, and less abdominal pain that those who did not change their fiber intake.
Too much fiber may also cause nutrient deficiencies, as it can interfere with the body's ability to absorb essential nutrients. This unwanted result is because the fiber binds with minerals, including calcium, magnesium, zinc, and iron.
Symptoms of consuming too much fiber may be reduced by increasing fluid intake.
The symptoms of eating too much fiber can be reduced by:
- reducing fiber consumption
- increasing fluid consumption
- getting more exercise
- avoiding food that increases bloating, such as chewing gum
A person with severe symptoms may choose to adopt a low-fiber diet, which means eating 10 g of fiber a day until their symptoms can be better managed. This diet is most often prescribed for individuals with serious digestive conditions or after procedures.
According to the Food and Nutrition Board of the Institute of Medicine, a low-fiber diet can meet a person's daily nutritional needs.
A low-fiber diet emphasizes:
- bread and grain products with less than 2 g of fiber per serving
- canned or cooked fruits and vegetables
- well-cooked meats
Hidden sources of fiber include products that contain the following ingredients:
- inulin, a hard to digest polysaccharide
- soy hulls
- guar gum
- oat fiber
Best sources of fiber
There are two basic kinds of fiber, soluble and insoluble. Although the body cannot digest either of them, they are both necessary for a healthy diet.
Soluble fiber breaks down in the water found in the digestive system and forms a gel. It helps keep stools soft and slows the digestive process.
Insoluble fiber does not break down at all, as it passes through the digestive system. It adds bulk to bowel movements and helps to move food along.
Individuals can strive to reach the recommended daily level of dietary fiber by eating a diet rich in:
whole fruit, though fruit juice is low in fiber
- nuts and seeds
- whole grains
It is essential to include a variety of fiber-rich foods in the diet. This ensures that a person will obtain a wide range of nutrients in addition to fiber. It will also help them to eat a good balance of soluble and insoluble fiber.
Naturally occurring fiber is usually easier for the body to handle than foods made with added fiber. So, whole grains and fresh fruits are usually more effective sources than high-fiber supplements or energy bars.
Benefit of fiber in the diet
Fiber may help to reduce the risk of heart disease and lower cholesterol.
A good balance of fiber in the diet is associated with a host of health benefits. These include:
- reduced risk of heart disease, diabetes, obesity, and colorectal cancer
- lower blood pressure
- lower cholesterol
- improved gastrointestinal health
- help with weight management
- more regular bowel movements
When someone has eaten too much fiber, the discomfort will pass over time, as the body eliminates the fibrous foods.
A person may relieve their discomfort by decreasing their fiber intake, increasing the amount of water they drink, and exercising more.
Note that fiber is an essential part of a healthy diet. Once following a low-fiber diet has helped a person with their symptoms, they can consider re-introducing fiber in limited amounts, so the body has time to adapt.
When increasing dietary fiber, it is vital to drink more fluids. An individual should aim for 8 glasses of water a day, and make a habit of choosing low or no-sugar beverages.
Achieving the recommended daily fiber targets is worth the effort because the health dangers of not eating enough fiber greatly outweigh the discomfort of eating too much.