How Much Fiber Should You Eat Every Day?

How Much Fiber Should You Eat Every Day.jpeg

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 farmer doesn't wait to find out. Had the farmer postponed his sowing until he understood seed germination, he 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 in 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 Childhood, How 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:

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

How Much Fiber Should You Eat Every Day?

How Much Fiber Should You Eat Every Day.jpeg

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 farmer doesn't wait to find out. Had the farmer postponed his sowing until he understood seed germination, he 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 in 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 Childhood, How 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:

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

How Much Fiber Should You Eat Every Day?

How Much Fiber Should You Eat Every Day.jpeg

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 farmer doesn't wait to find out. Had the farmer postponed his sowing until he understood seed germination, he 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 in 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 Childhood, How 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:

Image Credit: Sally Plank / Flickr. This image has been modified.

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Paleo Diet May Undermine Benefit of CrossFit Exercise

NF-Sept6 Paleo Diets May Negate Benefits of Exercise.jpeg

Much of the low-carb and paleo reasoning revolves around insulin. To quote a paleo blogger, "carbohydrates increase insulin, the root of all evil when it comes to dieting and health." So the logic follows that because carbs increase insulin, we should stick mostly to meat, which is fat and protein with no carbs, so no increase in insulin, right?

Wrong.

We've known for half a century that if you give someone just a steak: no carbs, no sugar, no starch; their insulin goes up. Carbs make our insulin go up, but so does protein.

In 1997 an insulin index of foods was published, ranking 38 foods to determine which stimulates higher insulin levels. Researchers compared a large apple and all its sugar, a cup of oatmeal packed with carbs, a cup and a half of white flour pasta, a big bun-less burger with no carbs at all, to half of a salmon fillet. As you can see in the graph in my video Paleo Diets May Negate Benefits of Exercise, the meat produced the highest insulin levels.

Researchers only looked at beef and fish, but subsequent data showed that that there's no significant difference between the insulin spike from beef, chicken, or pork--they're all just as high. Thus, protein and fat rich foods may induce substantial insulin secretion. In fact, meat protein causes as much insulin release as pure sugar.

So, based on the insulin logic, if low-carbers and paleo folks really believed insulin to be the root of all evil, then they would be eating big bowls of spaghetti day in and day out before they would ever consume meat.

They are correct in believing that having hyperinsulinemia, high levels of insulin in the blood like type 2 diabetics have, is not a good thing, and may increase cancer risk. But if low-carb and paleo dieters stuck to their own insulin theory, then they would be out telling everyone to start eating plant-based. Vegetarians have significantly lower insulin levels even at the same weight as omnivores. This is true for ovo-lacto-vegetarians, lacto-vegetarians, and vegans. Meat-eaters have up to 50% higher insulin levels.

Researchers from the University of Memphis put a variety of people on a vegan diet (men, women, younger folks, older folks, skinny and fat) and their insulin levels dropped significantly within just three weeks. And then, just by adding egg whites back to their diet, their insulin production rose 60% within four days.

In a study out of MIT, researchers doubled participants' carbohydrate intake, and their insulin levels went down. Why? Because the researchers weren't feeding people jellybeans and sugar cookies, they were feeding people whole, plant foods, lots of whole grains, beans, fruits, and vegetables.

What if we put someone on a very-low carb diet, like an Atkins diet? Low carb advocates such as Dr. Westman assumed that it would lower insulin levels. Dr. Westman is the author of the new Atkins books, after Dr. Atkins died obese with, according to the medical examiner, a history of heart attack, congestive heart failure, and hypertension. But, Dr. Westman was wrong in his assumption. There are no significant drop in insulin levels on very low-carb diets. Instead, there is a significant rise in LDL cholesterol levels, the number one risk factor for our number one killer, heart disease.

Atkins is an easy target though. No matter how many "new" Atkins diets that come out, it's still old news. What about the paleo diet? The paleo movement gets a lot of things right. They tell people to ditch dairy and doughnuts, eat lots of fruits, nuts, and vegetables, and cut out a lot of processed junk food. But a new study published in the International Journal of Exercise Science is pretty concerning. Researchers took young healthy people, put them on a Paleolithic diet along with a CrossFit-based, high-intensity circuit training exercise program.

If you lose enough weight exercising, you can temporarily drop our cholesterol levels no matter what you eat. You can see that with stomach stapling surgery, tuberculosis, chemotherapy, a cocaine habit, etc. Just losing weight by any means can lower cholesterol, which makes the results of the Paleo/Crossfit study all the more troubling. After ten weeks of hardcore workouts and weight loss, the participants' LDL cholesterol still went up. And it was even worse for those who started out the healthiest. Those starting out with excellent LDL's (under 70), had a 20% elevation in LDL cholesterol, and their HDL dropped. Exercise is supposed to boost our good cholesterol, not lower it.

The paleo diet's deleterious impact on blood fats was not only significant, but substantial enough to counteract the improvements commonly seen with improved fitness and body composition. Exercise is supposed to make things better.

On the other hand, if we put people instead on a plant-based diet and a modest exercise program, mostly just walking-based; within three weeks their bad cholesterol can drop 20% and their insulin levels 30%, despite a 75-80% carbohydrate diet, whereas the paleo diets appeared to "negate the positive effects of exercise."

I touched on paleo diets before in Paleolithic Lessons, and I featured a guest blog on the subject: Will The Real Paleo Diet Please Stand Up?

but my favorite paleo videos are probably The Problem With the Paleo Diet Argument and Lose Two Pounds in One Sitting: Taking the Mioscenic Route.

I wrote a book on low carb diets in general (now available free full-text online) and touched on it in Atkins Diet: Trouble Keeping It Up and Low Carb Diets and Coronary Blood Flow.

And if you're thinking, but what about the size of the cholesterol, small and dense versus large and fluffy? Please see my video Does Cholesterol Size Matter?

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--2013: Uprooting the Leading Causes of Death, More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

Image Credit: Vincent Lit / Flickr

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Fettuccini Alfredo

This easy pasta dish, traditionally made with cheese, milk, butter and oil, has been given a healthy makeover, using cashews and white beans to create the creamy white sauce. The cashews add richness while the white beans help keep the calories down. Print Fettuccini Alfredo Prep time:  15 mins Cook time:  10 mins Total time:  25...

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The post Fettuccini Alfredo appeared first on Straight Up Food.

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Around the Globe in 50 Delicious Main Dishes

Historically and globally, a plant-based diet has been traditional and standard, primarily based on accessibility. It was not until the last half of the 20th Century that meat and processed foods had the chance to take center stage due to innovative farming practices and industrialization of food production…much to the demise of our health. Now, because it …

Original Link

Around the Globe in 50 Delicious Main Dishes

Historically and globally, a plant-based diet has been traditional and standard, primarily based on accessibility. It was not until the last half of the 20th Century that meat and processed foods had the chance to take center stage due to innovative farming practices and industrialization of food production…much to the demise of our health. Now, because it …

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What To Do if You Suspect Gluten Problems

NF-Mar1 How to Diagnose Gluten Intolerance.jpeg

Symptoms of gluten sensitivity include irritable bowel type symptoms such as bloating, abdominal pain, and changes in bowel habits, as well as systemic manifestations such as brain fog, headache, fatigue, depression, joint and muscle aches, numbness in the extremities, skin rash, or anemia. I previously discussed why people who suspect they might be gluten sensitive should not go on a gluten-free diet. But if that's true, what should they do?

The first thing is a formal evaluation for celiac disease, which currently involves blood tests and a small intestinal biopsy. If the evaluation is positive, then a gluten-free diet is necessary. If it's negative, it's best to try a healthier diet with more fruits, vegetables, whole grains and beans while avoiding processed junk. In the past, a gluten-free diet had many benefits over the traditional American diet because it required increasing fruit and vegetable intake--so no wonder people felt better eating gluten-free: no more unhealthy bread products, no more fast food restaurants. Now, there is just as much gluten-free junk out there.

If a healthy diet doesn't help, then the next step is to try ruling out other causes of chronic gastrointestinal distress. In a study of 84 people who claim gluten causes them adverse reactions (they're referred to in the literature as"PWAWGs," People Who Avoid Wheat and/or Gluten), highlighted in my video, How to Diagnose Gluten Intolerance, about a third didn't appear to have gluten sensitivity at all. Instead, they either had an overgrowth of bacteria in their small intestine, were fructose or lactose intolerant, or had a neuromuscular disorder like gastroparesis or pelvic floor dysfunction. Only if those are also ruled out, would I suggest people suffering from chronic suspicious symptoms try a gluten-free diet. If symptoms improve, stick with it and maybe re-challenge with gluten periodically.

Unlike the treatment for celiac disease, a gluten-free diet for gluten sensitivity is ideal not only to prevent serious complications from an autoimmune reaction, but to resolve symptoms and try to improve a patient's quality of life. However, a gluten-free diet itself can also reduce quality of life, so it's a matter of trying to continually strike the balance. For example, gluten-free foods can be expensive, averaging about triple the cost. Most people would benefit from buying an extra bunch of kale or blueberries instead.

No current data suggests that that general population should maintain a gluten-free lifestyle, but for those with celiac disease, a wheat allergy, or a sensitivity diagnosis, gluten-free diets can be a lifesaver.

For more on gluten, check out Is Gluten Sensitivity Real? and Gluten-Free Diets: Separating the Wheat from the Chat.

Some food strategies that may help with irritable bowel symptoms are covered in a few of my previous videos, such as Kiwifruit for Irritable Bowel Syndrome and Cayenne Pepper for Irritable Bowel Syndrome and Chronic Indigestion.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Jeremy Segrott/ Flickr

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How a Gluten-Free Diet Can Be Harmful

NF-Feb23 Gluten-Free Diets - Separating the Wheat from the Chat .jpeg

Until only a few years ago, almost the whole of the scientific world maintained that the wheat protein gluten would provoke negative effects only in people with rare conditions such as celiac disease or wheat allergies. But by the early part of 2013, it was largely becoming accepted that some non-celiac patients could suffer from gluten or wheat sensitivity. Indeed, a consensus panel of experts now officially recognizes three gluten-related conditions, wheat allergy, celiac disease and gluten sensitivity.

What percentage of the population should avoid wheat? About 1 in a 1,000 may have a wheat allergy, and nearly 1 in a 100 may have celiac disease. Celiac disease appears to be on the rise, though there's still less than about a 1 in 10,000 chance an American will be diagnosed with celiac in a given year. Our best estimate for wheat sensitivity is in the same general range as celiac, slightly higher than 1 percent. That's still potentially millions of people who may have been suffering for years who could have been cured by simple dietary means, yet who were unrecognized and unaided by the medical profession.

Although gluten sensitivity continues to gain medical credibility, we still don't know how it works. We don't know how much gluten can be tolerated, if it's reversible or not, or what the long-term complications might be of not sticking to a gluten-free diet. Considering the lack of knowledge, people with gluten sensitivity should consider reintroducing gluten back into their diet every year to see if it's still causing problems.

The reason health professionals don't want to see people on gluten-free diets unless absolutely necessary is that, for the 98 percent of people that don't have gluten issues, whole grains--including the gluten grains wheat, barley and rye--are health promoting, linked to reduced risk of coronary heart disease, cancer, diabetes, obesity and other chronic diseases.

Because some people have a peanut allergy doesn't mean everyone should avoid peanuts. There is no evidence to suggest that following a gluten-free diet has any significant benefits in the general population. Indeed, there is some evidence to suggest that a gluten-free diet may adversely affect gut health in those without celiac disease, gluten sensitivity, or wheat allergy. A study out of Spain, highlighted in my video, Gluten-Free Diets: Separating the Wheat from the Chat, found that a month on a gluten-free diet may hurt our gut flora and immune function, potentially setting those on gluten-free diets up for an overgrowth of harmful bacteria in their intestines. Why? Because the very components wheat sensitive people have problems with, like FODMAP and fructans, may act as prebiotics and feed our good bacteria.

Gluten, itself, may also boost immune function. After less than a week on added gluten protein, subjects experienced significantly increased natural killer cell activity, which could be expected to improve our body's ability to fight cancer and viral infections. Another study found that high gluten bread improved triglyceride levels better than regular gluten bread.

Ironically, one of the greatest threats gluten-free diets pose may be the gluten itself. Self-prescription of gluten withdrawal may undermine our ability to pick up celiac disease, the much more serious form of gluten intolerance. The way we diagnose celiac is by looking for the inflammation caused by gluten in celiac sufferers, but if they haven't been eating a lot of gluten, we might miss the disease. Hence, rather than being on a gluten-free diet, we want celiac suspects to be on a gluten-loaded diet. We're talking 4-6 slices of gluten packed bread every day for at least a month so we can definitively diagnose the disease.

Why does it matter to get a formal diagnosis if you're already on a gluten-free diet? Well, it's a genetic disease, so you'll know to test the family. But most importantly, many people on gluten-free diets are not actually on gluten-free diets. Even 20 parts per million can be toxic to someone with celiac. Many on "gluten-free diets" inadvertently eat gluten. Sometimes gluten-free products are contaminated, so even foods labeled "gluten-free" may still not be safe for celiac sufferers.

As editorialized in the Lancet, the irony of many celiac patients not knowing their diagnosis, while millions of non-sufferers banish gluten from their lives, can be considered a public health farce.


Though the medical profession now recognizes wheat sensitivity as a discrete entity, it's still not clear if it's actually the gluten to which people are reacting. For a review of the controversy, see Is Gluten Sensitivity Real?

In How to Diagnose Gluten Intolerance, I go step by step how someone may want to proceed who suspects they might be sensitive to gluten-containing grains.

More on the benefits of whole grains in general in Whole Grains May Work As Well As Drugs and Alzheimer's Disease: Grain Brain or Meathead?

More on keeping our gut flora happy in videos such as Prebiotics: Tending Our Inner Garden and How to Change Your Enterotype.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Whatsername? / Flickr

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Gluten Sensitivity Put to the Test

NF-Feb18 Is Gluten Sensitivity Real?.jpeg

In 1980, researchers in England reported a series of women with no evidence of celiac disease (the autoimmune disorder associated with gluten intolerance), who nevertheless resolved their chronic diarrhea on a gluten-free diet. The medical profession was skeptical at the time that non-celiac gluten sensitivity existed, and even 30 years later, such patients were commonly referred to psychiatrists. Psychological testing of such patients, however, found no evidence that they were suffering from any kind of psychosomatic hysteria.

The medical profession has a history of dismissing diseases as all in people's heads--post-traumatic stress disorder, ulcerative colitis, migraines, ulcers, asthma, Parkinson's disease, and multiple sclerosis. Despite resistance from the prevailing medical community at the time, these health problems have subsequently been confirmed to be credible physiologically-based disorders rather than psychologically-based confabulations.

On the flipside, the internet is rife with unsubstantiated claims about gluten free diets, which has spilled over into the popular press to make gluten the diet villain du jour, with claims like "17 million Americans are gluten sensitive." However, it must be remembered that the gluten-free food industry is a big business. When literally billions are at stake, it's hard to trust anybody. As always, it's best to stick to the science.

What sort of evidence do we have for the existence of a condition presumed to be so widespread? Not much. The evidence base for such claims has been unfortunately very thin because we haven't had randomized controlled trials demonstrating that the entity even exists. The gold-standard for confirming non-celiac gluten sensitivity requires a gluten-free diet, followed by a double-blind, randomized, placebo-controlled food challenge. For example, give people a muffin and don't tell them if it's gluten-free or gluten-filled--to control for placebo effects--and see what happens. The reason this is necessary is because when you actually do this, a number of quote-unquote "gluten-sensitive" patients don't react at all to disguised gluten and instead react to the gluten-free placebo.

We never had that level of evidence until 2011, when a double-blind, randomized placebo-controlled trial was published, which tested to see if patients complaining of irritable bowel symptoms who claimed they felt better on a gluten free diet--despite not having celiac disease--actually could tell if they were given gluten containing bread and muffins or gluten-free bread and muffins.

Subjects started out gluten-free and symptom-free for two weeks and then were challenged with the bread and muffins. In my video, Is Gluten Sensitivity Real?, you can see what happened to the 15 patients who got the placebo, meaning they started out on a gluten-free diet and continued on a gluten-free diet. They got worse. Just the thought that they may be eating something that was bad for them made them feel crampy and bloated. This is what's called the nocebo effect. The placebo effect is when you give someone something useless and they feel better; the nocebo effect is when you give someone something harmless and they feel worse. On the other hand, the small group that got the actual gluten, felt even worse still. The researchers concluded that non-celiac gluten intolerance may therefore indeed exist.

It was a small study, though, and even though the researchers claimed the gluten-free bread and muffins were indistinguishable, maybe at some level the patients could tell which was which. So in 2012, researchers in Italy took 920 patients that had been diagnosed with non-celiac gluten sensitivity and put them to the test with a double-blinded wheat challenge by giving them capsules filled with wheat flour or filled with placebo powder. More than two-thirds failed the test, such as getting worse on the placebo or better on the wheat. But of those that passed, there was a clear benefit to staying on the wheat-free diet. The researchers concluded that their findings confirmed the existence of a non-celiac wheat sensitivity. Note I said "wheat sensitivity," not "gluten sensitivity."

Gluten itself may not be causing gut symptoms at all. Most people with wheat sensitivity have a variety of other food sensitivities. Two thirds are sensitive to cow's milk protein, and many are sensitive to eggs. If we put people on a diet low in common triggers of irritable bowel symptoms, and then challenge them with gluten, there's no effect. We find the same increase in symptoms with high gluten, low gluten, or no gluten diets, calling into question the very existence of non-celiac gluten sensitivity.

Interestingly, despite being informed that avoiding gluten didn't seem to do a thing for their gut symptoms, many participants opted to continue following a gluten-free diet as they subjectively described "feeling better." So researchers wondered if avoiding gluten might improve the mood of those with wheat sensitivity. Indeed, short-term exposure to gluten appeared to induce feelings of depression in these patients. Whether non-celiac gluten sensitivity is a disease of the mind or the gut, it is no longer a condition that can be dismissed.


More than 10,000 articles have been published on gluten in medical journals--intimidating even for me! Combined with the multi-billion dollar financial interests on both sides, it makes for a difficult task. But I think I did it! This is the first of a 3-part series summarizing the best available science on gluten. Also check out: Gluten-Free Diets: Separating the Wheat from the Chat and How to Diagnose Gluten Intolerance.

Why this apparent increase in food sensitivities in recent decades? It could be because of pollutant exposure (see Alkylphenol Endocrine Disruptors and Allergies and Dietary Sources of Alkylphenol Endocrine Disruptors).

What can we do about preventing so-called atopic diseases (like allergies, asthma, and eczema)? See my videos Preventing Allergies in Adulthood and Preventing Allergies in Childhood. The weirdest example of an emerging food sensitivity may be the tick-bite related meat allergy story I review in Alpha Gal and the Lone Star Tick and Tick Bites, Meat Allergies, and Chronic Urticaria.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Guillaume Paumier / Flickr

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