Let’s be honest, most of us are probably not getting a sufficient amount of fiber in our diets each day, but did you know it’s actually possible to eat too much fiber?
Don’t freak out quite yet. The consequences of consuming too much fiber are not nearly as serious those that can result from a low-fiber diet. Actually, how much fiber per day you need is actually a fluid figure and depends greatly on how much you’ve already been getting.
So, how does one have too much fiber? How do you know if it’s a bad thing? Let’s take a look at when a high-fiber diet may actually lead to too much fiber in your diet.
How Much Fiber Per Day Should You Get?
High amounts of fiber in the diet are associated with a lower risk of arteriosclerosis (a form of heart disease), diabetes and general degenerative disease. (1, 2, 3) On average, Americans consume about 15 grams of fiber per day, which is… not enough. (4) In fact, it’s closer to about half of what most people need.
According to the Institute of Medicine and the American Heart Association, the amount of fiber people need each day is: (6)
- 19 grams for children 1–3 years old
- 25 grams for children 4–8 years old
- 26 grams for girls 9–18 years old
- 31 grams for boys 9–13 years old
- 38 grams for males between 14–50
- 25 grams for females between 19–50
- 21 grams for men over 50
- 30 grams for women over 50
Other sources suggest that the best way to maintain optimal fiber is to eat 14 grams for every 1,000 calories you eat each day. (7) On a standard 2,000-calorie diet, that lands at 28 grams, somewhere between the optimal intake numbers for men and women listed above.
Does it really matter how much fiber per day you get, though? Of course the answer is “yes.” It’s not just a big deal for you — it matters for your children, as well.
Research released in 2016 found that, after a certain amount of time, poor dietary fiber intake can affect the gut microbiome more permanently and even pass along a “less diverse” colony of healthy gut bacteria to your offspring. (8) This is an example of how epigenetics is affected by diet and lifestyle.
The issue for most people is that it can be a challenge to keep up with that required fiber on a Standard American Diet due to the habit we sometimes have of avoiding high-fiber foods like leafy greens, fruits and legumes.
How Much Is Too Much Fiber?
You may be asking, “Josh, if people aren’t getting enough, why are you telling me I can have too much fiber?” Simple: Because the side effects associated with eating too much fiber are often found in those trying to up their intake too fast because they realize the importance of a high-fiber diet.
There is evidence that suggests a high end of fiber intake can cause symptoms — namely that people will probably begin noticing ongoing problems when they eat more than 45–70 grams of fiber consistently each day. (9, 10) That would be a challenge for most people, though.
The two more pressing concerns for the large majority of people are:
- Introducing too much fiber too fast and without proper precautions
- Taking excessive fiber supplements, including weight loss pills
For example, if you are one of those average 15-grams-a-day folks and you start eating 38 grams and make no other dietary changes, you’re likely to feel the effects, most of which are uncomfortable and potentially embarrassing.
In addition, if you supplement your fiber intake and overdo it, you might have the same issues.
Symptoms of Too Much Fiber on the Body
There are two main types of fiber: soluble and insoluble. Soluble fiber is broken down and fermented in the colon, while insoluble fiber travels through the digestive tract unabsorbed, providing bulking and causing stool to move more quickly through the gut. Primary sources of soluble fiber include oats, barley, nuts, seeds, peas, plus some fruits and vegetables. (11)
While an appropriate amount of soluble fiber helps aid in weight loss as it attracts water and forms into a gel, slowing the digestive process, too much soluble fiber can cause constipation, particularly for those who already struggle with the problem. (12)
A 2012 study of 63 subjects found that patients with constipation while on a high-fiber diet found relief when decreasing their daily fiber intake significantly. (13)
If you regularly struggle with constipation on a high-fiber diet, it’s possible that decreasing your overall fiber intake and/or reducing the amount of soluble fiber you eat might help relieve your symptoms.
On the inverse, another symptom of too much fiber is diarrhea. You may have guessed it, but while constipation is often a symptom of having too much soluble fiber, diarrhea occurs many times when people have too much insoluble fiber. (14)
Insoluble fiber travels undigested through your system to bulk stool and speed digestion. It is found in whole grains, most fruits and vegetables most frequently. Too much insoluble fiber without proper soluble fiber can potentially provide a speed that leads to diarrhea.
3. Bloating and Gas
Another common problem with extra fiber intake, especially right after a rapid increase, is digestive discomfort, including bloating and flatulence. (15, 16) This is especially true for people with irritable bowel syndrome, or IBS. (17)
4. Abdominal Pain/Cramps
Usually related to constipation issues, cramping is another possible effect of eating too much fiber. Reducing overall fiber intake can help lessen abdominal cramping.
Patients with IBS who are trying to increase their fiber intake may also want to consider increasing soluble fiber more than insoluble, because there is limited research that shows a high level of insoluble fiber may actually worsen the stomach pain associated with IBS. (18)
5. Mineral Deficits
Fiber binds to minerals. (19) Through the body’s normal digestive process, this is not generally a problem. However, there is some evidence that too much fiber can bind to minerals at such rates that it’s possible you might not absorb them efficiently.
For example, one study found an increase in calcium absorption for diabetes patients increasing their fiber intake too quickly. (20)
This is generally not going to be a problem if you balance your fiber intake by eating a huge variety of colors in your food (meaning you maintain variety), because too much insoluble fiber is often the culprit in these situations.
Another complication with mineral absorption is also related to the source of your fiber — non-sprouted grains and legumes often contain high levels of phytate (also known as phytic acid), a group of antinutrients that are known to block the body from absorbing iron, calcium and zinc. (21, 22, 23) To avoid consuming high levels of phytate, stick to sprouted grains wherever possible, and soak beans and nuts for at least 30 minutes before consuming.
I’ll touch more on water intake below, but it’s important when increasing fiber intake to also up the amount of water you drink each day. When you stay hydrated, the fiber you eat can absorb the water it needs without leeching it from other necessary systems.
However, if you drastically increase your fiber without increasing your water intake, or consistently eat more than 50 grams of fiber a day, you are more likely to become dehydrated. This symptom is also connected to diarrhea and constipation, so they may appear together.
7. GERD/Acid Reflux
While traditional medicine tells us that acid reflux is caused by too much stomach acid, there is actually a growing body of evidence that it may be caused (or exacerbated) by low stomach acid and carbohydrate malabsorption. (24)
A low amount of stomach acid results in poorly digested food, including carbohydrates that contain the fiber your body needs. When those only-partially-digested carbohydrates get into the intestines, they can result in SIBO (small intestinal bacterial overgrowth), which, in turn, causes intra-abdominal pressure. That pressure is likely the underlying cause of acid reflux. (25)
On the one hand, reducing overall carbohydrate intake will decrease the amount of fiber in the diet and can help relieve some of these symptoms. However, in these cases, it’s probably best to figure out why your stomach wasn’t producing enough acid in the first place in order to deal with that issue.
8. Intestinal Blockage
The worst possible scenario (an extremely rare one, at that) for too much fiber is a risk for intestinal blockage, a medical emergency requiring immediate attention. It’s unlikely that most people will ever experience this, but there are people at risk for a shrinkage of the intestines, known as colon stricture, which increases the chance of intestinal blockage. That is mainly a risk for people with Crohn’s disease and can be managed with a low-fiber diet. (26)
People with poor intestinal function are also potentially at risk for a specific kind of blockage known as a phytobezoar, a collection of indigestible plant fiber, skins and seeds. One treatment method for phytobezoars is to drastically reduce fiber intake for a period of time. (27)
High-Fiber Foods to Limit
As you’ve gathered by this point, most of the symptoms of too much fiber are determined by how much fiber per day you’re already taking in and how quickly you may try to increase that level. The solution, at that point, is usually not to limit a specific type of food or food group.
For some, though, doctors may prescribe a low-fiber diet for a period of time. Those with a narrowing (stricture) of the bowel because of tumors or inflammatory disease, those who have recently had bowel surgery, and people on radiation treatments are the likely candidates.
In that case, your doctor will most likely recommend you discontinue or significantly limit your intake of whole grains, gluten-free grains, such as quinoa, raw fruits, raw or undercooked veggies, dried legumes, seeds, and nuts. These low-fiber diets do encourage intake of refined grains (grains without bran, endosperm or both).
On the whole, a low-fiber diet is a short-term solution for specific problems and conditions. Most people will not benefit from a permanently low-fiber diet.
In reality, the larger food-related problem occurs with “super” fibers like glucomannan. This konjac root-derived fiber has been known to aid in weight loss for many people and can be eaten in the form of shirataki noodles or powder in smoothies. (28) If you were consuming vast amounts of glucomannan per day, it’s likely you would experience at least one or more of the above symptoms.
Much more concerning, though, is fiber supplementation. If you are thoughtfully eating a diet full of whole, life-giving fruits, vegetables, seeds, nuts and legumes, you (probably) will be able to reach your daily fiber needs most of the time. Actually, high fiber intake is one of the major benefits of a well-structured vegan diet.
While it may be possible for you to take fiber supplements to improve your macros, over-supplementing with fiber is much more likely to cause gastrointestinal conditions like the ones I described above.
If you take a fiber supplement, you should closely monitor the fiber you’re eating — you can do this by using any of a number of great food-tracking smartphone apps — so you’re sticking to the daily recommended value for your age and gender. Most evidence suggests that up to 45 or 50 grams per day can be well-tolerated, but it’s not necessary to eat that much fiber.
Don’t forget that some supplements not necessary labeled for “fiber” may also contain fiber. Multivitamins generally don’t have added fiber, but thermogenic supplements and fat burners for weight loss may contain fiber to speed bowel movements and aid weight loss. One such supplement is Lipozene, which contains 4.5 grams in a day’s suggested dosage of glucomannan. Only about four grams per day can be tolerated because of that particular fiber’s bulking power.
What to Eat if You Are Getting Too Much Fiber
I briefly outlined a low-fiber diet above, but if you need to cut your fiber intake, whether for a short period or a long period of time, you should focus your diet around: (29)
- Grass-fed, humanely raised tender meat, seafood and eggs
- Smooth, organic peanut butter and almond butter
- Full-fat, (preferably raw, cultured) dairy (in small amounts)
- Tender, well-cooked fresh or canned vegetables
- Skinless, cooked sweet potatoes and purple potatoes
- Soft, skinless fruits (in small amounts)
- Pure, unprocessed juice (not sugary fruit juices)
- Healthy fats like avocado, olive oil and coconut oil
Most conventional low-fiber diet lists also recommend eating refined grains, sugary desserts and processed cereal, which I do not suggest.
While on a low-fiber diet, it’s best to avoid:
- Processed meats (which you should avoid anyway)
- Tough, gristly meats
- All whole grains, including brown rice and sprouted bread
- Cereal grains and seeds, such as quinoa
- Raw or steamed vegetables
- Potatoes with skin
- All fruits
- Potato chips
How to Get the Right Amount of Fiber
If I’ve said it once, I’ve said it… well, I’m not sure how many times, but: Eating a variety of whole foods is the best way to maintain proper fiber intake (as well as all other important vitamins and nutrients).
Not focusing on one specific food or type of food to get all of your fiber is the only way to ensure you are eating both soluble and insoluble fibers as part of a balanced, healthy diet. Look for a variety of colors on your plate — fruits, vegetables, seeds and legumes are not bad for you, and most people need to eat more of them.
Balance is key. If you’re not sure how much fiber you eat, track your diet and figure it out. Modern technology makes this easier than it’s ever been in history, so if you’re concerned you’re getting too little or too much fiber, that’s a great place to start.
How to Counteract Too Much Fiber
If you’ve recently increased how much fiber you eat and are experiencing some of the above symptoms, here are some natural ways to try and counteract those effects.
- Consume fermented foods and drinks. Fermented foods like sauerkraut and organic pickles, along with fermented drinks including kefir and kombucha, can help to keep your gut microbiome in top functioning order. When your gut is operating at its best capacity, it’s easier for your body to digest and process the fiber you eat.
- Drink a ton of water. Many people don’t make the connection between fiber and water, but your body needs more water to work with more fiber. Because soluble fiber attracts water, increasing that without more water can result in dehydration. One study found that drinking around 60 ounces of water each day significantly improved fiber digestion. (30) Try drinking half of your body weight in ounces each day if you can. This equates to 80 ounces for a 160-pound individual, which sounds like a lot, but you’ll likely notice a difference in your overall well-being if you keep hydrated.
- Balance soluble and insoluble fiber. I probably sound like a broken record at this point, but making sure to eat a variety of foods so you don’t eat too much of one fiber will help you avoid symptoms of too much fiber.
- Increase your fiber intake by two to three grams a day at first. Don’t feel like you need to go from 15 to 38 grams of fiber a day in one pass. Whether you’re taking a fiber supplement or improving your diet, try going slowly by adding between two and three grams more fiber each day to allow your body time to adjust.
- Exercise. Yes, adding moderate levels of exercise into your routine can help your body shift and process fiber. See what works for you — yoga, walking and biking are great options to get your gastrointestinal tract to shape up.
- Try an elimination diet. The above symptoms aren’t only caused by how much fiber per day you’re getting. It’s possible to experience the same things because of food allergies or intolerances. Especially if you’ve already determined you’re eating a healthy amount of varying types of fiber and drinking plenty of water, it may serve you to try an elimination diet, discontinuing your consumption of common allergen foods and then reintroducing them one by one.
Precautions with Too Much Fiber
If you experience recurring symptoms of too much fiber, even if you aren’t sure it’s related to this issue or not, it may be a good idea to visit your health care provider. Knowledgeable doctors and naturopaths will be able to recognize additional symptoms or other underlying causes, and it isn’t usually wise to self-diagnose, especially when it comes to repetitive gastrointestinal problems.
Reducing fiber intake for a while? Don’t fall into the temptation of filling that empty space with refined grains, sodas and sugary desserts. Sure, these may be low in fiber, but they also hold no nutritional benefits.
Lastly, if you are increasing your fiber intake, take it slowly, especially if you’re taking fiber supplements. Look at how much fiber per day you’re recommended to take in and shoot for around that number, rather than taking the overachiever approach and doubling it.
Final Thoughts on Too Much Fiber
- Most people on a Western diet don’t get enough fiber. On average, an American eats 15 grams per day, somewhere around half the recommended amount.
- Eating sufficient fiber is associated with a lowered risk of disease and is important to overall health.
- It is possible (although improbable) to eat too much fiber on a regular basis. People can begin experiencing symptoms of too much fiber somewhere between a consistent 45–70 grams each day. It’s more likely to get too much fiber by taking a fiber supplement.
- Many people who experience the effects of too much fiber are reacting to a quick, drastic increase in fiber intake, often as a result of realizing they don’t eat enough fiber.
- Symptoms of too much fiber include constipation, diarrhea, abdominal pain, gas/bloating, mineral deficits, dehydration, acid reflux and (in rare cases) intestinal blockage.
- To counteract these effects, increase your fiber intake by two to three grams a day, drink plenty of water (aim for half your pounds of body weight in ounces), eat fermentable foods and drinks, exercise, and eat a variety of foods to balance soluble and insoluble fiber.
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