Warning signs of too much fiber

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.

Fiber requirements

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.

[interrupt] 

What to do

If you are consuming too much fiber in your diet, try the following:

• Stop eating products with added fiber, such as high-fiber cereal bars or high-fiber breads
• At mealtime, replace high-fiber foods, including grains, with lower-fiber alternatives
• Avoid foods that cause bloating, such as sugar-free gum and candy
• Choose cooked over raw veggies
• Increase fluid intake
• Exercise more

In one prospective, longitudinal case study involving 63 patients with idiopathic constipation, reduced fiber intake decreased constipation, bloating, and stomach pain, and increased the frequency of bowel movements.

Specifically, during a period of 6 months, 41 patients were on a no-fiber diet, 16 were on a reduced-fiber diet, and 6 continued on a high-fiber diet due to personal or religious factors. Participants who stopped their dietary fiber intake completely went from having 1 bowel movement every 3.75 days to having 1 per day. In those who reduced their fiber intake, bowel movement frequency went from 1 every 4.19 days to 1 every 1.9 days.

High-fiber foods

Here is a list of high-fiber foods with values rounded to the nearest 0.5 g:

Fruits	Serving size	Total fiber
Raspberries	1 cup	8.0 g
Pear	1 medium	5.5 g
Apple, with skin	1 medium	4.5 g
Banana	1 medium	3.0 g
Green peas, boiled	1 cup	9.0 g
Broccoli, boiled	1 cup chopped	5.0 g
Potato, with skin, baked	1 medium	4.0 g
Sweet corn, boiled	1 cup	3.5 g
Cauliflower, raw	1 cup chopped	2.0 g
Carrot, raw	1 medium	1.5 g
Spaghetti, whole wheat, cooked	1 cup	6.0 g
Barley, pearled, cooked	1 cup	6.0 g
Bran flakes	3/4 cup	5.5 g
Oat bran muffin	1 medium	5.0 g
Oatmeal, instant, cooked	1 cup	5.0 g
Popcorn, air-popped	3 cups	3.5 g
Brown rice, cooked	1 cup	3.5 g
Bread, whole wheat	1 slice	2.0 g
Bread, rye	1 slice	2.0 g
Chia seeds	1 oz	10.0 g
Almonds	1 oz (23 nuts)	3.5 g
Pistachios	1 oz (49 nuts)	3.0 g

[interrupt] 

Finally, remember that fiber is a really important part of the diet. If a person feels sick from eating too much fiber, then a low-fiber diet may be a good idea for some time, with limited amounts of fiber gradually re-introduced into the diet.