Dietary fiber is known for its ability to suppress appetite and increase satiety. This nutrient supports digestive function and colon health while making weight loss easier. That's why medical professionals worldwide recommend the consumption of fruits, veggies, whole grains and other high-fiber foods. Eating too much fiber, on the other hand, isn't necessarily better. Gas, bloating, nutrient deficiencies and constipation are all common side effects.
When consumed in excess, fiber may cause bloating, gas and even constipation. It can also worsen IBS symptoms and affect nutrient absorption. Increase your fiber intake gradually to prevent these side effects. Try not to exceed 70 grams per day.
Is Fiber Really Necessary?
More than 95 percent of Americans are not getting enough fiber in their diet. This puts them at risk for constipation, heart disease, diabetes and obesity, among other disorders. A 2015 study published in The American Journal of Clinical Nutrition has linked high-fiber diets to lower rates of colorectal cancer.
This nutrient keeps your digestive system running smoothly and increases satiety. According to a 2017 research paper in the Journal of Obesity & Eating Disorders, a lack of fiber may increase the risk of cardiovascular problems and contribute to the onset of diabetes. Fresh fruits, leafy green vegetables, oats and other high-fiber foods regulate your blood sugar levels and prevent insulin spikes. At the same time, they help reduce bad cholesterol and promote gut health.
Dietary fiber may also aid in weight loss. As Today's Dietician notes, fiber-rich foods curb hunger and keep you full longer. Eating an extra 14 grams of fiber daily can help reduce your food intake by up to 10 percent and reduce appetite by 5 percent. Think about how full you feel after eating oatmeal, salad or fresh fruit.
How Much Is Too Much?
When it comes to your fiber intake, more isn't always better. In fact, eating too much fiber can affect digestive health. When consumed in excess, this nutrient may cause bloating, gas, diarrhea and other gastrointestinal symptoms. It may also worsen constipation and irritable bowel syndrome.
- Raw wheat bran — 12.5 grams of fiber per serving (1/2 cup)
- Navy beans — 9.6 grams of fiber per serving
- Yellow beans — 9.2 grams of fiber per serving
- Split peas — 8.1 grams of fiber per serving
- Lentils — 7.8 grams of fiber per serving
- Raw oat bran — 7.5 grams of fiber per serving (1/2 cup)
- Pear — 5.5 grams of fiber per serving
- Soybeans — 5.2 grams of fiber per serving
- Chia seeds — 4.1 grams of fiber per serving
- Raspberries — 4 grams of fiber per serving
- Dried figs — 3.7 grams of fiber per serving
- Almonds — 3.5 grams of fiber per serving
- Bananas — 3.1 grams of fiber per serving
- Quinoa — 2.6 grams of fiber per serving
Certain supplements, such as psyllium husk and Metamucil, can boost digestive health and prevent fiber deficiency. Psyllium husk powder, for example, contains 7 grams of fiber per serving. Simply mix it into water, fruit juices or smoothies and drink it right away. Although there is no upper limit on fiber, excessive consumption may cause digestive problems.
IBS and Fiber
About 10 percent to 15 percent of people worldwide suffer from irritable bowel syndrome (IBS), according to the International Foundation for Gastrointestinal Disorders. Approximately 40 percent experience severe symptoms that interfere with their daily lives. This condition is more common in women, causing stomach pain, bloating, flatulence, diarrhea or constipation, low energy and fatigue.
The general recommendation for IBS management is to eat more fiber. However, this strategy doesn't work for everyone. According to Today's Dietician, fiber tolerance varies from one person to another. This nutrient may relieve constipation and regulate bowel movements, but it can also worsen your symptoms.
Let's take the low-FODMAP diet, for example. This dietary plan limits the consumption of certain foods that may trigger IBS symptoms. The problem is that many fiber-rich foods, such as cauliflower, broccoli, garlic and onions, are also high in FODMAPs. Yet, this diet has been proven effective in IBS management. If you have this condition, try to gradually increase your fiber intake and see how your body reacts.
Bloating and Constipation
Nuts, seeds, fruits, vegetables, legumes and other foods are rich in soluble fiber, which absorbs water and increases stool bulk. Insoluble fiber, on the other hand, doesn't absorb liquids; instead, it stimulates bowel movements. Most foods contain both types of fiber.
Soluble fibers, such as beta-glucan and pectins, ferment in the gut and feed the good bacteria living in your digestive tract. That's why they're commonly referred to as prebiotics. When the gut bacteria break down soluble fiber, they produce methane and other gases, leading to bloating and flatulence. That's why the low-FODMAP diet limits fruits, cruciferous vegetables, tofu and other foods high in fermentable fibers.
Additionally, too much fiber in the diet can make constipation worse. This nutrient adds bulk to the stool but doesn't always increase bowel motility, which depends on the speed of transit through the gut. As a result, you may experience gas and constipation due to waste buildup in the colon. A 2012 study published in the World Journal of Gastroenterology has found that reducing or cutting out fiber may actually relieve constipation, abdominal bloating and stomach pain.
Vitamin and Mineral Deficiencies
Consuming too much fiber can lead to nutrient deficiencies. According to a 2018 review featured in the journal Fibers, this nutrient may affect the absorption of iron, calcium, copper, magnesium and fat-soluble vitamins. Furthermore, soluble fibers may reduce protein digestion in the small intestine.
The same source indicates that fiber affects lipid metabolism, which isn't necessarily a bad thing. This nutrient binds to cholesterol, triglycerides and bile acids, making it easier for your body to excrete them. As WebMD notes, soluble fiber may improve blood lipids and slow sugar absorption into the bloodstream. The downside is that it can also reduce or block the absorption of certain drugs.
- Today's Dietician: Fiber's Link With Satiety and Weight Control
- U.S. News & World Report: Fast Fiber Facts: What It Is and How to Get Enough
- Harvard T.H. Chan School of Public Health: Fiber
- The American Journal of Clinical Nutrition: Dietary Fiber Intake and Risk of Colorectal Cancer and Incident and Recurrent Adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial
- Journal of Obesity & Eating Disorders: Insight of Dietary Fibers Consumption and Obesity Prevention
- Journal of the Academy of Nutrition and Dietetics: Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber
- UCSF Health: Increasing Fiber Intake
- Health.gov: Dietary Guidelines, 2015-2020: Table A13-1. Food Sources Ranked by Amounts of Dietary Fiber and Energy per Standard Food Portions and per 100 Grams of Foods
- NutritionValue.Org: Wheat Bran, Crude
- NutritionValue.Org: Oat Bran, Raw
- SELFNutritionData: Psyllium Husk Powder
- About IBS: Statistics
- About IBS: Dietary Fiber
- Today's Dietician: Fiber & Irritable Bowel Syndrome — Strategies
- Gastro Journal: A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome
- MedlinePlus: Soluble vs. Insoluble Fiber
- Nature Reviews: Gastroenterology & Hepatology: Expert Consensus Document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) Consensus Statement on the Definition and Scope of Prebiotics
- World Journal of Gastroenterology: Stopping or Reducing Dietary Fiber Intake Reduces Constipation and Its Associated Symptoms
- MDPI: Fibers: Does Dietary Fiber Affect the Levels of Nutritional Components After Feed Formulation?
- WebMD: Fiber
- Duke.edu: Fiber-How