Naveed Saleh, MD, MS, for MDLinx | September 05, 2019
Fiber is vital for a healthy digestive system. It facilitates fermentation and gas formation, and helps improve the bulk and regularity of bowel movements. In addition, a high-fiber diet can help with the regulation of lipid and blood pressure levels, diabetes control, and weight maintenance.
But is it possible to get too much of a good thing?
As with most everything, moderation of this carbohydrate is key. Eating too much fiber (> 70 g daily)—as is common with whole- or raw-food diets—can result in you making a beeline for the bathroom, as well as other uncomfortable side effects.
The American Heart Association recommends fiber intake from a variety of foods. Total dietary fiber consumption should range from 25 to 30 g daily from food—not supplement—sources. More specifically, the Academy of Nutrition and Dietetics recommends 25 g of fiber per day for women and 38 g a day for men. Adults aged 50 years and older should consume less fiber, at 21 g per day for women and 28 g per day for men. Pregnant or lactating women should eat 28 g of fiber per day.
Types of fiber
Fiber exists in two forms: soluble and insoluble. Even though the body can’t absorb either form, they are both necessary. Soluble fiber breaks down in water and forms a gel that keeps feces soft while slowing digestion. Insoluble fiber does not break down, instead adding bulk to stool and decreasing transit times. The body needs both types of fiber, so most research simply focuses on total fiber intake.
Too much fiber
Symptoms of eating too much fiber can include bloating, gas, cramping, constipation, diarrhea, reduction in appetite, and early satiety.
One of the negative side effects of overconsumption of fiber includes the underabsorption of key micronutrients, since fiber binds with minerals, such calcium, iron, magnesium, and zinc. Furthermore, high-volume meals can make it difficult to keep up energy intake, resulting in weight loss or lack of weight/muscle gain. Lastly, intestinal obstruction can occur in the setting of copious fiber intake but limited fluid intake.