The phrase "too much of a good thing can be a bad thing" is true when it comes to nutrition. While fiber is an important part of a healthy diet, there might be a link between eating too much fiber and stomach pain.
Reducing your fiber consumption and drinking a lot of water can provide relief, but you should also see a doctor if you’ve eaten too much fiber and have stomach pain.
Recommended Daily Fiber Intake
According to the National Academies of Science, Engineering and Medicine, fiber is a macronutrient that improves laxation, reduces your risk of heart disease and helps regulate your blood sugar.
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The USDA's 2015–2020 Dietary Guidelines for Americans recommend the following daily fiber intake for adults:
- Women between the ages of 19 and 30: 28 grams
- Men between the ages of 19 and 30: 33.6 grams
- Women between the ages of 31 and 50: 25.2 grams
- Men between the ages of 31 and 50: 30.8 grams
- Women above the age of 50: 22.4 grams
- Men above the age of 50: 28 grams
In fact, the guidelines list this substance as one of the nutrients of public health concern because most Americans don't get enough of it in their diet. According to Harvard Medical School (HMS), most adults get only 10 to 15 grams of fiber per day. The USDA attributes this to under-consumption of fruits, vegetables and whole grains.
But what about people who consume too much fiber? The National Academies of Science, Engineering and Medicine states that an upper limit has not been set for fiber consumption, because even though eating too much fiber may cause a stomach ache and other gastrointestinal issues, it does not have any other deleterious effects on your health.
The Academy of Nutrition and Dietetics considers the gastrointestinal side effects of too much fiber unavoidable but tolerable in light of the many benefits this nutrient has to offer. In fact, an October 2015 study published in the journal Nature Communications found that rural South African diets that consisted of over 66 grams of fiber per day were associated with health benefits, such as a lower risk of colon cancer.
Types of Fiber
Dietary fiber is the compound in plants that the human body cannot digest. According to the USDA, dietary fiber consists of non-digestible carbohydrates and lignin, which are intrinsic in plants. As HMS notes, there are two types of dietary fiber: soluble and insoluble fiber. Both types are good for you.
Soluble fiber dissolves in water and forms a gummy, gel-like substance. This type of fiber reduces the risk of heart problems, helps bring down your cholesterol levels and regulates your blood sugar levels. HMS lists lima beans, black beans, Brussels sprouts, sweet potato, broccoli, avocado, turnips and pears as some of the sources of soluble fiber.
Insoluble fiber, also known as "roughage," does not dissolve — it passes through your digestive system relatively intact. This nutrient adds bulk to your stools, regulating your bowel movements and preventing constipation. HMS mentions cauliflower, potatoes, green beans, wheat bran and whole wheat flour as good sources of insoluble fiber.
Apart from dietary fiber, the USDA also lists functional fiber as a type of fiber. It defines functional fiber as non-digestible carbohydrates that are either extracted from natural sources or else synthetically manufactured and added to foods, drinks and supplements.
According to HMS, it's preferable to get your fiber from whole foods rather than supplements. The latter don't provide the various types of fiber, vitamins, minerals and other nutrients found in whole foods. However, the Cleveland Clinic notes that doctors may prescribe fiber supplements to people who are not getting enough of this nutrient through their diet and may be struggling with constipation and diarrhea.
Too Much Fiber and Stomach Pain
According to the International Foundation for Gastrointestinal Disorders, adding too much fiber to your diet too quickly can be worse than being on a low-fiber diet. If you're increasing your intake of fibrous foods, HMS advises doing it gradually to give your digestive system time to adjust to it.
It is also recommended that you increase your intake of water as you increase your intake of this nutrient, especially if you're taking fiber supplements. Per the Cleveland Clinic, you should be drinking at least 8 ounces of liquid with fiber supplements. Taking certain fiber supplements without enough water may cause the fiber to swell, causing constipation and choking.
According to the Academy of Nutrition and Dietetics, high intakes of functional fiber may cause excessive flatulence, bloating and diarrhea. The fermentation of dietary fiber along with other undigested proteins and carbohydrates in your digestive system may also cause intestinal gas and other digestive issues.
Duke University notes that excess consumption of this nutrient may result in a lack of appetite as well as weight loss and the inability to build muscle because you're unable to get enough energy or nutrition from your food. This is because fiber can bind to certain nutrients like iron, calcium, zinc and magnesium, and block their absorption by the body.
The Academy of Nutrition and Dietetics recommends consulting a dietitian to make sure you're getting sufficient amounts of this nutrient from multiple natural sources in moderate amounts throughout the day, and to ensure you don't consume too much of it and get a stomach ache. Per HMS, you should also consult your doctor before dramatically increasing your fiber intake, especially if you face digestive issues like constipation.
Too Much Fiber: Constipation Cure
Duke University suggests removing sources of added fiber from your diet to relieve bloating and other symptoms of too much fiber. These may include high-fiber cereals and bars since they can be harder for your digestive system to handle than natural dietary fiber.
The experts at Duke University also advise taking a look at your meals. If all your meals have high-fiber components, switching out some of your grains and proteins for low-fiber options and eating more cooked food instead of raw food could help. You should also avoid other foods that cause bloating, like chewing gum, candy and cough drops.
The Mayo Clinic recommends drinking plenty of water to help relieve constipation caused by excess consumption of this nutrient, since it works best when it absorbs water. The researchers at the Mayo Clinic also suggest cutting back on high-fiber foods for a short time to reduce flatulence, and then slowly introducing them back into your diet after a short break.
You should visit a doctor if you've eaten too much fiber and have persistent stomach pain. In general, it's recommended to consult a healthcare provider before making any major lifestyle or diet change.
- USDA: “2015–2020 Dietary Guidelines for Americans”
- Harvard Medical School: “Should I Be Eating More Fiber?”
- National Academies of Science, Engineering and Medicine: “Dietary Reference Intakes: Macronutrients”
- Academy of Nutrition and Dietetics: “Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber”
- U.S. National Library of Medicine: “Fat, Fiber and Cancer Risk in African Americans and Rural Africans”
- Cleveland Clinic: “Improving Your Health With Fiber”
- International Foundation for Gastrointestinal Disorders: “Dietary Fiber”
- Mayo Clinic: “Dietary Fiber: Essential for a Healthy Diet”
- Mayo Clinic: “Belching, Intestinal Gas and Bloating: Tips for Reducing Them”
- Duke University: “Fiber — How Much Is Too Much”