Juice cleanses may seem like a healthy fad, but nutrition experts advise against them on a number of grounds. One big reason: They lack fiber.
Nutritionists often tout the benefits of a fiber-rich diet filled with a variety of vegetables and other plant-based foods. Indeed, it’s common knowledge that eating your veggies is good for your health.
“Consumption of fiber has long been associated with several health benefits, including reduction in the risk of several diseases including cardiovascular disease, Type 2 diabetes and certain types of cancer,” said Jonathan Valdez, owner of Genki Nutrition and New York City media spokesperson for the New York State Academy of Nutrition and Dietetics.
He highlighted other pros like improvements in immune function, constipation prevention, and reduction in blood pressure, cholesterol and inflammation.
But for the overachievers out there, is it possible to go overboard and eat a diet that’s too rich in fiber? Is too much fiber even a thing?
We asked nutrition experts to break it down.
First of all, what exactly is fiber?
“Dietary fiber comes from the edible parts of a plant that we cannot digest nor absorb in the small intestine,” said Melissa Halas, registered dietitian and author of several books for kids and adults that promote fiber’s health benefits.
Fiber can be insoluble or soluble, both of which are “superheroes for your health,” Halas added. The former helps prevent constipation and keep you regular, while the latter can lower your body’s cholesterol levels and make you feel full ― and most plants contain both types, in different amounts.
“Soluble fiber is easily fermented by gut bacteria and is used as energy by your cell’s large intestines,” she continued, noting that consuming fiber positively impacts the composition of microbes in your gut. “The more you feed your gut, the greater microbial diversity it will have. This is good because having a healthy, diverse microbiome is essential for overall immunity and brain health.”
There’s no need to focus on the breakdown of soluble versus insoluble fiber in your diet, but rather you should think about your overall fiber intake. Eating a variety of fruits, vegetables, whole grains, legumes, herbs and spices will give you plenty of both types. And the benefits are endless.
Can you eat too much fiber?
“Most Americans are not even coming close to getting enough fiber in our daily diets,” said Frances Largeman-Roth, a registered dietitian nutritionist and author of “Smoothies & Juices: Prevention Healing Kitchen.”
In fact, more than 97% of men and 90% of women in the U.S. do not consume the recommended 25-35 grams of fiber per day, according to the 2020-2025 Dietary Guidelines for Americans. This is unsurprising, as much of the processed and fast food popular with Americans in particular contains very little fiber, Largeman-Roth added.
Meanwhile, “foods with fiber take longer to eat and tend to be more filling than many other foods,” noted Jill Weisenberger, a registered dietitian nutritionist and creator of the “Stick With It” video course.
That fullness would make eating too much fiber difficult, but it’s certainly possible.
“Anyone with certain gastrointestinal problems, especially those susceptible to an intestinal blockage, could eat too much fiber. And it’s possible to get too much fiber from fiber supplements or fiber-fortified foods,” Weisenberger said.
“If you go overboard ― say you had two stuffed bean burritos and several bowls of kale, plus some edamame ― and go over 35 grams, you may experience symptoms of too much fiber,” Largeman-Roth suggested.
What happens to your body if you eat too much fiber?
“Eating too much fiber, or suddenly increasing your fiber intake, can cause uncomfortable gastrointestinal symptoms, like bloating, gas, flatulence and diarrhea,” said nutritionist Alyssa Northrop.
If you’re trying to boost the amount of fiber in your diet, be mindful of these possible side effects, but don’t let them stop you from pursuing a nutrient-rich diet. Pay attention to other possible root causes, as well.
“Unfortunately, the signs of too much fiber may also mimic other gastrointestinal issues, like irritable bowel syndrome or inflammatory bowel disease,” Halas said. “So, feeling gassy, crampy, bloated or excessively full doesn’t necessarily mean you’re getting too much fiber.”
She advised using a fiber tracker app for a few days to measure how much you’re consuming and take note of the plant sources you’re using. If you have a history of disordered eating, however, it may be best to avoid tracking systems.
“You can go much higher than the recommended fiber intake. Many of my vegetarian or vegan clients take in 40-45 grams of fiber a day without any issues and reap the short- and long-term health benefits,” she added.
There have also been concerns that a very high-fiber diet might lead to decreased absorption of health-promoting minerals like calcium, magnesium and zinc, and while this can be true, research suggests that eating foods with naturally occurring fiber overall leads to increased mineral levels due to the fact that these plant-based foods tend to be more nutrient-rich overall.
“This is more of a concern with excessive use of fiber supplements,” Weisenberger noted. So as long as no other health issues restrict your diet in a conflicting way, the benefits of eating nutritious plants generally outweigh the risks.
“People in some cultures eat much more fiber than the average American, and they tend to have less chronic disease,” Northrop noted. “So the issue isn’t really about eating too much fiber ― it’s about eating more fiber than your body is used to. It takes time for your digestive system and the bacteria in your gut to adjust to a higher fiber diet.”
What should you do if you eat too much fiber?
“If you’re experiencing uncomfortable symptoms, try backing off on the amount of fiber you’re eating to give your digestive system a rest,” Northrop said. “Then gradually build up your intake over time to get your digestive system and gut flora accustomed to eating more fiber.”
In addition to cutting back on the amount of fiber you consume in a day, Largeman-Roth advised varying your sources of fiber.
“Instead of eating bowlfuls of high fiber cereal to get what you need in a day, have some cereal, and also berries and other fruit, salad, cooked veggies (which are easier to digest than raw), whole grains, seeds, beans and nuts,” she said. “Also, while fiber supplements can be helpful if you’re struggling to get enough, you shouldn’t rely on them for all your daily fiber.”
Consult with a professional if you have concerns about your fiber intake or continue to experience bad symptoms.
“Intentional excessive fiber intake could indicate an eating disorder or disordered eating, in which case, reach out to your medical provider,” Halas said. “Working with a dietitian is always helpful to evaluate your overall diet and fiber intake, significantly beyond macros!”