How Much Fiber Should You Eat Every Day

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How Much Fiber Should You Eat Every Day?

High dietary fiber intake may help prevent strokes. The belief that dietary fiber intake is protectively associated with certain diseases was postulated 40 years ago and then enormously fueled and kept alive by a great body of science since. Today, it is generally believed that eating lots of fiber-rich foods helps prevent obesity, diabetes, and cardiovascular diseases such as stroke.

Strokes are the second most common cause of death worldwide. Moreover, stroke is a leading cause of disability, and so preventing strokes in the first place—what’s called primary prevention—should, therefore, be a key public health priority (see How to Prevent a Stroke).

The best observational studies to date found that fiber appears to significantly protect against the risk of stroke. Different strokes for different folks, depending, evidently, on how much fiber they ate. Notably, increasing fiber just seven grams a day was associated with a 7% reduction in stroke risk. And seven grams is easy, that’s like a serving of whole grain pasta with tomato sauce and an apple.

What’s the mechanism? Maybe it’s that fiber helps lower cholesterol and blood sugar levels. Or, it could just be that those eating more fiber are just eating more vegetables, or fewer calories, or less meat and fat, or improving digestion, all of which may slim us down and lower our blood pressure and the amount of inflammation in our bodies. Does it really matter, though? As Dr. Burkitt commented on the biblical passage, “A man scatters seed on the land—the seed sprouts and opens—how, he does not know;” the farmers don’t wait to find out. Had the farmers postponed sowing until they understood seed germination, they would not have lasted very long. So yes, let’s keep trying to figure out why fiber is protective, but in the meanwhile, we should be increasing our intake of fiber, which is to say increasing our intake of whole plant foods.

It’s never too early to start eating healthier. Strokes are one of many complications of arterial stiffness. Though our first stroke might not happen until our 50’s, our arteries may have been stiffening for decades leading up to it. Hundreds of kids were followed for 24 years, from age 13 up through 36 and researchers found that  lower intake of fiber during a young age was associated with stiffening of the arteries leading up to the brain. Even by age 13, they could see differences in arterial stiffness depending on diet. Fiber intake is important at any age.

Again, it doesn’t take much. One extra apple a day or an extra quarter cup of broccoli might translate into meaningful differences in arterial stiffness in adulthood. If you really don’t want a stroke, we should try to get 25 grams a day of soluble fiber (found concentrated in beans, oats, nuts, and berries) and 47 grams a day of insoluble fiber (concentrated in whole grains). One would have to eat an extraordinarily healthy diet to get that much, yet these cut-off values could be considered as the minimum recommended daily intake of soluble and insoluble fiber to prevent stroke. The researchers admit these are higher than those commonly and arbitrarily proposed as “adequate” levels by scientific societies, but should we care  about what authorities think is practical? They should just share the best scienceand let us make up our own minds.

Someone funded by Kellogg’s wrote in to complain that in practice, such fiber intakes are “unachievable” and that the message should just be the more, the better—like maybe just have a bowl of cereal or something.

The real Dr. Kellogg was actually one of our most famous physicians, credited for being one of the first to sound the alarm about smoking, and who may have been the first American physician to have recognized the field of nutrition as a science. He would be rolling in his grave today if he knew what his family’s company had become. 

More on preventing strokes can be found here:

More on the wonders of fiber in:

It really is never too early to start eating healthier. See, for example, Heart Disease Starts in ChildhoodHow to Prevent Prediabetes in Children, Heart Disease May Start in the Womb, and Should All Children Have their Cholesterol Checked?

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

62 responses to “How Much Fiber Should You Eat Every Day?

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  1. Would love a pictorial guide to daily fiber intake:

    Examples of daily food intake that add up to the ‘recommended’ levels and also the ideal.

    Then maybe I could convince myself to cut back on olive oil and leave more room for carrots…

    1. Try a whole food plant based diet. It’s that simple. It would be impossible to not get enough fiber eating a whole food plant based diet.

      1. Exactly. Its extremely easy with steel cut oats and avocados. With whole plant food I’m curious if there a max because my calories are up and so is my fiber.

    2. Hi Pat. I cannot include pictures in this reply, but you can think of it like this: Vegetables have about 4 grams of fiber per serving, fruits have 3 grams of fiber per serving, beans have 6 grams, and whole grains have 3 grams. I’ll let you do the math or get creative with pictures on your refrigerator of how to get the recommended amount of daily fiber. I hope that helps!
      -Stephanie (a NutritionFacts moderator)

      1. Could you comment on the subject of too much dietary fiber intake, particularly for older folks? After reading Dr. Greger’s book and following the website videos and blogs, I went “Full Greger” on a whole grain and plant based diet. In retrospect, I may have been following Doctor’s orders too explicitly for a 70 year-old digestive system. Since my conversion a couple of years ago, stool has been basically diarrhea. I have recently done some additional research and find that daily fiber intake beyond 70 mg, easily reached on a whole grain and plant based diet, can get messy and should be reduced in any event for people over 50. I hate moving away from the prescription, but have substituted low-fat yogurt, eggs, balsamic rice, and sourdough bread for higher-fiber options like oatmeal and brown rice with a return to normal re my stool. I worry about the negative impact these foods will have on my heart and arteries but don’t think constant diarrhea is healthy either. I will appreciate your take on this situation. Thank you.

  2. Having following a lot of your recommendations on diet and lifestyle, thanks to you, I am still able to keep diabetes at bay, have still maintained my weight loss of 55 lbs., still run and exercise at 72 years of age and all is well with the world. I have not achieved vegan status but, I have become a staunch vegetarian. (I like my home made yogurt.) Sugar has been removed 98% from my diet and the results are amazing. Now to the point: Given that cancer is found in every living being on the planet and also given that our immune system naturally keeps it at bay, given that it is maintained in a healthy lifestyle, is sugar really not the main culprit here?

    Cancer feeds on sugar, then the cancer secretes lactic acid which is then converted back to sugar again by the liver because our blood becomes too acidic. Continued intake of sugar (in any form) contributes to increased demands on the pancreas to produce more insulin and so on and so forth. So, is it not the insulin that actually does the damage to the endothelial system of the body by damaging the inner walls of our arteries? Cholesterol, a most important component of our immune system, hormone control and maintenance, repairs the damage done by the insulin. I call is artery putty that patches the damage done by the insulin. More insulin, more damage. Blocked coronary arteries. Therefore, is it not true to say that sugar is the main culprit and not the cholesterol? Drop the sugar, the pancreas slows down in the production of insulin and the arterial damage is reduced and the cholesterol is not a problem. True or false?

    I actually read a story that, in a seniors residence where sugar intake is controlled very carefully, there was a great number of residence whose cholesterol was more than 250! And they were fine! No drugs to control the cholesterol either. I have heard it said by a pathologist that if we could eliminate sugar from our diets, cancer, heart attacks and stroke would drop by 98%. Wouldn’t that be grand, and wouldn’t Big Pharma take a Big Hit?

    I love what you do. You have saved my life and I send your message out to anyone and everyone who will listen.

    1. Paul Pinel: I’m happy to hear that the information on this site has helped you to achieve some health goals.

      As for the rest of your post, I’d say that your basic understanding of cancer is incorrect. The mayo clinic has this to say regarding sugar and cancer:
      “Sugar doesn’t make cancer grow faster. All cells, including cancer cells, depend on blood sugar (glucose) for energy. But giving more sugar to cancer cells doesn’t speed their growth. Likewise, depriving cancer cells of sugar doesn’t slow their growth.” To learn more:

      The mayo clinic page does note that “…there is some evidence that consuming large amounts of sugar is associated with an increased risk of certain cancers, including esophageal cancer. It can also lead to weight gain and increase the risk of obesity and diabetes, which may increase the risk of cancer.” But this information is often twisted by people to mean that we shouldn’t eat foods that contain natural carbs/”sugars” from whole foods, such as fruit and whole grains. As modrator Rami once noted: “People often use this idea Your brain, and red blood cells and every other cell in your body uses glucose as its primary fuel source. Sugar from whole grains and fruits has no linkage with disease, and no studies have demonstrated such a linkage. The studies in fact show the opposite, in that these foods prevent chronic disease.”

      Moderator Joseph once wrote the following on the topic: “The concept that sugar feeds cancer cells is misleading. Processed and refined foods can be health depleting foods for cancer patients, whereas health supporting foods are food rich in fiber and antioxidant. Fruits fall into this category, often the dark berries are best and also low in fruit sugar as is.” To learn more about why the concept that sugar feeds cancer is misleading:

      I don’t think anyone promotes tables sugar as a health food. For one thing, it is devoid of that fiber that is so important as discussed in the article on this page. At the same time, sugar is not quite the devil that people make it out to be either. A doctor named Kempner used a white rice, fruit juice and sugar diet to reverse eye sight loss caused by diabetes at a time when no thought such a thing was possible. My point is: It’s important to have some perspective on the issue of sugar.

      For your point about cholesterol being important – I couldn’t agree more. However, water is also important for humans to sustain life. And too much water can kill us. The fact that cholesterol is important is irrelevant to discussions about what happens when we have too much cholesterol in our systems.

    2. Paul Pinel, Please remember that our bodies make all the cholesterol we need. We get excess cholesterol from animal foods. There are many videos and articles on Dr G’s site discussing this.

      Also, Dr Esselstyn, who actually did the research on how to reverse heart disease, has an excellent video here: This describes and explains the role of cholesterol in the arteries and why it builds up, not just that it does build up, then what actually causes heart attacks, which is rarely just the narrowing of the arteries by cholesterol buildup.

      Back to cancer, the definitive research by T Colin Campbell (The China Study, Whole, and many videos on Youtube) at Cornell mostly, over 40 or 50 years shows that it is actually animal protein that stimulates cancer growth. He was able to demonstrate over and over, and many colleagues did as well, that cancer growth was stopped when animal protein was at 5%, and stimulated when it was at 20% of the diet. In between those figures he showed increasing cancer as animal protein percentage increased. He then verified that the same holds true for humans in his huge study in China, where populations eating little or no animal protein had little or no cancer, while those eating more animal protein had more cancer, depending on their level of animal protein consumption. He also demonstrated that protein from plants did not have this effect of stimulating cancer growth. Here is a great talk on that subject:

      Most Americans have been brainwashed by industrial meat, egg, and milk producers (really, you can’t call them farmers) to believe that animal protein is superior, but honest research, not paid for by those folks, shows otherwise. Colin Campbell also talks about how damaging it is to consume too much protein, which, again, few Americans are aware of, yet most participate in.

      The sweet spot for protein consumption seems to be between 6-12% of the diet, which is easily achieved by simply eating a wide variety of plant foods, including beans, whole grains, veggies, fruits, and a few nuts and seeds. I think we’d all agree that breast milk is the best food for human babies while they are growing their fastest, and the percentage of protein in it is only 0.8-0.9%.

    3. I too am 72 years old, have been a veggie for over 30 years. I am obese (overweight by 70 lbs). There is no added sugar in my diet, I eat pulses every day, salad every day, 300g fruit + porridge + flax for breakfast. I can walk for an hour. That is me, so could anyone explain why I am so fat?? It’s a bit rhetorical, because I guess it’s the beer I drink!? (6l per week). To lose any weight at all I need to diet strictly, even with my healthy way of eating, (‘sans’ beer).

      1. Kevin, You said it all: 61 beers a week? Have you considered the calories in that much beer? Or are you just pulling our collective leg?

        1. Rebecca – That’s a 6 and lowercase “L” so 6 liters per week, or about 2.5 12 oz beers per day. It still probably explains his problem, but it’s a far cry from 61, ha! It also depends on what kind of beers he’s drinking. If it’s Coors Light that’s like 200 kcal/day. IPAs could be 1,000+ kcals/day.

          1. Thanks for clarifying that, Dan. I thought you were really just checking to see if we’re awake out here in cyberspace. We do need to learn our metric system here in the US.

            I like my beer too, but only about one 12 ounce bottle every two or three days.

            Really, there are 1,000 calories in an IPA? Why such a big discrepancy?
            That seems really excessive to me, but of course I haven’t checked it out.
            I prefer an amber ale myself. IPA is far to hoppy for my palate.

            I don’t remember if you said you eat oils or other added fats. If so, that could be your problem. Many people have been unable to lose weight until they stop using oils. Have you seen the educational and entertaining video on Dr McDougall’s site, *From* *Fat* *Vegan* *to* *Skinny* *Bitch*? It’s well worth watching. Dr Esselstyn also reports on the science showing how refined oils, including extra virgin olive oil, cause your endothelial cells, which line the arteries, to be unable to expand and contract as needed for each heart beat. This contributes to heart disease.

  3. I don’t think that anybody’s going to argue that refined sugar issn’t bad for you. Can’t understand why people eat it. But I have been studying the information on this website for a number of years now. If i had to pick out one food that is most heavily linked to cancer it would have to be dairy.

    1. I recall a message I got from a teacher in high school way back when.  He stated that, and I quote “Too much of anything is bad.” Therefore, I consider that if you eat very little of a ‘non-processed food’, you are not going to have any real health issues. I believe in the need for probiotics in our microbiome in order to maintain a healthy gut which, it is being determined, is the well head of good health above all else. One cup of yogurt (which is all of the dairy I eat) with ground flax seed, hemp seed, turmeric, cinnamon, fresh ground pepper, blueberries and almond milk is an excellent source of so many nutrients. Put it this way, when I entered my doctor’s office after eighteen months, he stared and asked me, “How did you do that?” I now coach him in lifestyle and, thus far, everything is in the green as far as my health is concerned. Thank you for the reply.

      1. Swap the dairy yogurt for plain unsweetened non-gmo soy yogurt with all that lovely stuff in it, and then I’d agree it’s excellent and healthy ;-)

        1. Scott, I have tried soy yogurt and it wasn’t lovely at all. It was horrid. I have to drive 260 miles round trip to buy vegan imitation dairy and it is expensive, so throwing that nasty crap in the compost heap was painful. I don’t eat yogurt, but I would never recommend soy pudding. Oh, and I am one of the least fussy eaters I have ever met.

  4. I have been trying to up my fiber intake with the hope of dramatically reducing my total cholesterol level. I recently started adding black beans to my morning green smoothie and I like the result very much. Does blending beans have any affect on their fiber content?

    1. Hi! This is Corey one of the moderators answering questions on the site. From what I can find, blending shouldn’t have any effect on the fiber in your black beans. It is mostly soluble fiber and blending it may add some additional smoothness to your morning smoothie without negatively impacting the fiber content. Morning green smoothie cheers!!

  5. why o lord do doctors, scientists and the medical establishment always speak in terms of grams (of fat, of fiber, etc.) when we in the U.S. are taught to think in pounds and ounces? Yes, we can google to find an equivalent but I don’t get the protocol.

    1. Because the English system of weights and measures is awkward and much less used than the metric system. The USA has officially started the transition to the metric system. And I see that it is good.

      1. where can I find something on where we have begun the official transition to metric in the U.S. And why did they decide to wait until I was 70 yo? Idiots.

        1. I you’re 70 years old, perhaps you remember that the government tried to get us stubborn Americans to switch to the metric system back in the late ’60s to early ’70s, and failed miserably. It would be nice if the whole world were on the same system, and they tell me metric is easy (my Canadian friends all use it), but I’m resistant, too. I think the trick is just to start using metrics and get used to them instead of trying to convert the numbers.

  6. Dr. Kellogg may have been an advocate for nutrition, but he was a quack in my opinion. He advocated circumcision which is a barbaric, unnecessary mutilation with no real benefits. I read it was he that started the practise of circumcision in America, to stop masterbation. He was such a prude he did not even have sex with his wife!

    1. Kellogg was not just a quack, he was f-ing crazy. His views on tobacco were one of his few redeeming qualities. He developed corn flakes because he thought a bland uninteresting diet would keep people from masturbating. He didn’t just circumcise men, he also sewed their foreskins to their scrotums to prevent erections. He practiced chemical FGM by applying pure carbolic acid to women’s clitorises. He would use an enema machine to fill his patients’ bowels with several gallons of water, followed by yogurt. He advocated eugenics and racial segregation. Sure, he happened to have some views regarding nutrition that align with modern medical science, but for Dr. Greger to reference him in such an entirely uncritical fashion is deeply disappointing.

  7. I came across this pdf on the web while looking for a way to reverse my father’s AAA. Since it’s Lent now i’ve managed to get my dad and mum on a vegan diet. I’m supplementing with b12 but not epa/dha. I’d like to supplement but I’m not sure if it would hurt him more. Is it ok to supplement epa/dha? I’ve noticed that my father feels abdominal pain a few hours after a meal with turmeric in it. How often should I give turmeric to him? I’m limiting it to only a few times a week. I’d like to give him natto to eat, but I’m not sure if it’s safe to give him natto to eat either.

    Here’s the pdf:

    Where do I post so that the doctor can look at articles?

    Sorry for posting here I don’t know where to post to get a response.

    1. Gunne: Unfortunately, Dr. Greger is not able to answer most of the questions in the forum. However, we do have a team of volunteer moderators who try to answer questions when possible. I have forwarded your question to the list of questions for our medical moderators to answer. Please note that we don’t have enough volunteers to get all questions answered. An answer is not guaranteed. Good luck.

    2. Thanks for your comment Gunne.

      I had a look at the pdf you have attached, it certainly looks very interesting and from a reliable source and I managed to find the publication that is referenced at the end (see here). Please note that in this study, they used 100 mg/kg curcumin on mice. You can try similar dose unless contraindicated but it’s important to know that this an animal study and results may not be applicable to humans.

      You should check tolerability, but if you want to provide turmeric, then the University of Maryland recommends the following doses are recommended for adults (see here):

      Cut root: 1.5 to 3 g per day
      Dried, powdered root: 1 to 3 g per day
      Standardized powder (curcumin): 400 to 600 mg, 3 times per day
      Fluid extract (1:1) 30 to 90 drops a day
      Tincture (1:2): 15 to 30 drops, 4 times per day

      I would like to mention that Dr Greger has 2 videos on aortic aneurysm and I highly recommend you to watch them:

      Abdominal Aortic Aneurysms: Ticking Time Balloons

      How to Help Prevent Abdominal Aortic Aneurysms

      From the prevention video, it is important to cut down meat consumption and it is great that both your parents have managed to get on board. But equally important to increase consumption of fruits and vegetables, eat nuts and quit smoking (if applicable).

      In regards to omega-3 EPA/DHA supplementation, I found no contraindication. In fact, there was a study that demonstrated EPA to be a attenuating AAA (see here).

      I have found no studies or research regarding natty consumption and AAA and therefore I cannot make a definite recommendation.

      Hope this answer helps.

      1. Thank you for your reply. He’s had ulcers before so it’s good to know about that side effect. He has type 2 diabetes as well, whenever he gets metformin his mental abilities decline substantially. I’ll try giving more turmeric and try to tread carefully. I’ll get some vegan epa/dha supplements when I get a chance. They’re difficult to get in Australia.

    3. hi Gunne, not sure you will get this message, but I read your post about your father having abdominal pain some hours after consuming tumeric. I remember distinctly Dr Greger talking about tumeric’s ability to uncrease the contractions of the gall bladder, and therefore could present a real risk in someone who unknowingly had gallstones . If a stone was large or lodged in a bad position, consuming tumeric would increase the risk of a (dangerous) gall bladder attack. I am so sorry that I dont remember the exact video. Imay have timw later to look.. at any rate , since your fathers pain is consistent, I would (if I were you) get him checked out quickly for gall stones before serving up more tumeric. I am not a doctor, just a NF fan. All the best to you and your family!

      1. Here is the video that offers a cautionary note to people wanting to include tumeric in their diet regularly. Just as a side note, the only time in the past I have ever suffered pains (gall bladder attacks mostly) was at the start of lent. Apparently sudden major dietary changes can bring this on, (according to my doctor ) but that being said, I still have my gallbladder intact, and I enjoy tumeric daily in my curries.

  8. After suffering a perforated ulcer in 1971, which returned a few years later, in 1978 I read a book called The Truth about Fibre in Your Food by Dr Lawrence Galton. I then went on a very High Fibre diet and within a year the ulcer had gone. This was before the discovery by two Australian Doctors that ulcers were caused by a virus and the resultant ‘DUAL’ tablets quickly got rid of any and all ulcers. However, back to fibre. Dr Galton knew that fibre was of no nutritional value but was of significant value when the undigested fibre hit the liquid in the bowel. Immediately it became swollen and triggered the brain to evacuate the bowel. Without fibre, constipation was a certainty, along with the resultant problems like colon cancer, diverticulosis et al.

    Sean Parker

    1. Thanks for your question.

      I will attach a publication that summarises the main methods used in clinical setting to determine arterial stiffness and I quote:

      Several methods for quantifying arterial mechanical properties have been proposed. These can be divided into techniques which apply propagative models to the circulation and those using non-propagative models [27]. Propagative models assume that the velocity with which a pulse wave travels along a given artery has a finite value [28]. Non-propagative methods include the Windkessel model that likens the circulation to a mechanical device found on old fire engines. A Windkessel pump was designed to transform the intermittent pulsing of a manual water pump into a continuous stream of water from a hose [16]. Similarly, modelling the circulation in this way separates its functions into conduit and cushioning functions. The Windkessel model has been criticized, however, since the arterial tree does not have separate conduit and cushioning functions, and because the model makes the assumption that PWV (pulse wave velocity) has infinite velocity [28].

      Inferences can be made about the mechanical properties of arteries by measuring pulse pressure or by measuring a variety of ‘stiffness indices’ in the form of outputs recorded from one of several commercially available devices. Such devices usually measure one of three possible types of arterial stiffness: systemic stiffness (i.e. a measure of the stiffness of the entire circulation); regional or segmental stiffness (i.e. a measure of the stiffness of a segment of the arterial tree); or local stiffness (i.e. a measure of the stiffness in a small section of one blood vessel under study) [29]. They can, however, provide information about more than one aspect of the circulation and can thus be classified as devices that: quantify pulse transit time; analyse the pressure pulse waveform; or provide direct estimation of vessel stiffness by the simultaneous assessment of arterial diameter and a corresponding distending pressure (Figure 1).

      When an article describes the ‘stiffness’ of a blood vessel, one must ask what is actually being referred to. This is because the term arterial ‘stiffness’ lacks a precise definition and has no mathematical relationship to the mechanical properties of arteries [30]. As such, arterial stiffness cannot be directly quantified [31]. The terms ‘compliance’ and ‘distensibility’ are often used interchangeably with ‘stiffness’ [32]. However, compliance (a change in volume or cross-sectional area for a given change in pressure) and distensibility (a fractional change in volume or cross-sectional area for a given change in pressure) are parameters that can be quantified and have units of measurement [1], unlike arterial stiffness that is a purely descriptive term that cannot be measured or quantified. Stiffness represents a convenient shorthand term for alterations in the mechanical properties of blood vessels.

      Hope this answer helps.

  9. Can anyone comment on the danger of a high fiber diet? I read a story where someone was consuming a very high fiber diet more than 100 g a day and developed an intestinal blockage because they weren’t drinking enough water.

    Is there any validity to this?

    Since going WFPB I tend to eat about 70-80 g of fiber per day…. If there is a fiber intake threshold where you should start drinking more water that would be good to know….

    1. Hi wjb,
      I’m one of the medical moderators here on the NF site.
      My question would be what is that person actually eating. Anyone eating a WFPBD should be getting a more than adequate amount of water because most of the foods we eat have a very high water content.
      I too have heard these kinds of stories but they were mostly related to elderly people often in nursing homes, who were taking or being given fiber supplements as laxatives to combat constipation and were not being given or were simply not drinking adequate water.
      If one is actually getting their fiber from fresh whole food I would think it virtually impossible to “overdose” on fiber. You might spend a little extra time in the bathroom but I can’t see any harm resulting.

  10. Dear Dr Greger,

    I am speaking on behalf of someone else who is suffering really badly from IBS and sometimes cannot sleep due to the stomach pain. They have been vegan for over a year and, although they had IBS before veganism, their IBS has become worse since. The main candidates that make it worse tend to be beans and vegetables like broccoli. All the articles I can find online speak about how veganism helps IBS but it has made him worse. He is committed to remaining vegan, yet he is suffering at the moment. What do you think is happening and what could you reccommend?

    Thank you

    1. IBS Sufferer: I’m wondering if the following talk from Dr. Klaper applies to your friend’s situation. Dr. Klaper talks about “failed vegans” and why that might happen. He has a theory that some people may experience problems on a vegan diet, because their bodies are literally addicted to meat and animal protein. Such a person’s body may have stopped producing an important substance. You can learn more from this snippet of the talk here:

      If your friend finds that theory compelling, I’d be happy to share the answer. Dr. Klaper has a protocol for fixing the situation. That protocol was described after the talk got cut-off in the video snippet above.

      Another suggestion I have is for your friend to do a phone consultation with Dr. Klaper. He is not free, but he is an expert and is actually willing to talk one on one with people. If your friend wants help fixing this problem by working with someone who really knows his nutrition, a consultation with Dr. Klaper may be the way to go.

      Hope that helps.

    2. I am vegan and I started suffering from IBS 5 years ago, the only relief I found was limiting foods with FODMAPS, please tell your friend to research it, Monash University in Australia have ongoing testing of fodmaps in food. Garlic, onions, beans (not green fresh ones), stone fruits, honey, are some of the foods that can give you problems with IBS. Also possible that you can become wheat intolerant, sometimes vegans eat too much bread, processed vegan food etc. Try sourdough spelt bread, fresh foods and smaller meals. There are many resources on the internet and print outs of list of foods and how much you can eat in one time, also there is an app for a smartphone.

  11. Is there such thing as too much fiber from the health perspective? Since practically all I eat are low calorie veggies, I get a LOT of fiber every day, like 120 gram very easily. I also consume tons of water, so no constipation issues or anything the like. But could it somehow be unhealthy or dangerous to consume that much fiber?

    1. Juuuuum: One of our volunteer medical moderators recently answered a similar question. I think the answer to your question is also in this answer. See what you think:

      from medical moderator payoung: “Anyone eating a WFPBD should be getting a more than adequate amount of water because most of the foods we eat have a very high water content. I too have heard these kinds of stories but they were mostly related to elderly people often in nursing homes, who were taking or being given fiber supplements as laxatives to combat constipation and were not being given or were simply not drinking adequate water. If one is actually getting their fiber from fresh whole food I would think it virtually impossible to “overdose” on fiber. You might spend a little extra time in the bathroom but I can’t see any harm resulting.”

    1. Hi Bruce. Great question! I’m Crystal, a nutritionist and Moderator on

      Generally, men and women have different nutritional needs. When public health professionals compose the Dietary Guidelines 2015-2020, they base recommendations on daily calorie intakes. The fibre DRI for men is higher because men require more calories to maintain a healthy body weight than women.

  12. Well written, thank you. Many people underestimate the importance of fibers.
    Fibers are components of plant cells which are not degraded in the intestines. They are partly degraded in the colon under the influence of bacteria.

    Fibers are most commonly divided into soluble and insoluble. Generally, insoluble fibers have an important role in preventing digestive disorders, whereas soluble fibers are significant for regulating diabetes, decreasing cholesterol, and fighting obesity.

  13. I’m a (high-carb!, wfpb) vegan bodybuilder and have been told that too much fiber can inhibit protein absorption. I currently get about 50-60g/day. Anything come up in the research about this?

  14. Dr. Kellogg also recommended burning little girls’ private parts with carbolic acid to “cure” masturbation. Look it up. He is not someone anyone should look up to for any reason.

  15. Since 2002 I have been hospitalized for small bowel obstructions several times. This, despite my eating largely a whole-foods, plant-based diet. Each time it happened, the doctors said I should avoid fiber for awhile and then start adding it back to my diet. Eventually I get to the point where I have a lot of fiber intake from vegetables, grains, and nuts. And then I will obstruct again. The most recent health practitioner I talked to indicated that I really should avoid heavy fiber almost indefinitely. I am torn about this because of the documented health benefits of fiber. I wish Dr. Greger would address this topic. I searched the site for “small bowel obstruction” and found nothing.

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