What Animal Protein Does in Your Colon

What Animal Protein Does in Your Colon.jpeg

There's a take-off of the industry slogan, "Beef: It's What's For Dinner" - "Beef: It's What's Rotting in Your Colon." I saw this on a shirt once with some friends and I was such the party pooper--no pun intended--explaining to everyone that meat is fully digested in the small intestine, and never makes it down into the colon. It's no fun hanging out with biology geeks.

But I was wrong!

It's been estimated that with a typical Western diet, up to 12 grams of protein can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction process can be toxic.

It's generally accepted that carbohydrate fermentation--the fiber and resistant starches that reach our colon--results in beneficial effects because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental. Protein fermentation mainly occurs in the lower end of colon and results in the production of potentially toxic metabolites. That may be why colorectal cancer and ulcerative colitis tends to happen lower down--because that's where the protein is putrefying.

Probably the simplest strategy to reduce the potential harm of protein fermentation is to reduce dietary protein intake. But the accumulation of these toxic byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. In my video, Bowel Wars: Hydrogen Sulfide vs. Butyrate, you can see a study out of Australia showed that if you give people foods containing resistant starch you can block the accumulation of potentially harmful byproducts of protein metabolism. Resistant starch is resistant to small intestine digestion and so it makes it down to our colon where it can feed our good bacteria. Resistant starch is found in cooked beans, split peas, chickpeas, lentils, raw oatmeal, and cooled cooked pasta (like macaroni salad). Apparently, the more starch that ends up in the colon, the less ammonia that is produced.

Of course, there's protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon. Hydrogen sulfide is the rotten egg gas that may play a role in the development of the inflammatory bowel disease, ulcerative colitis (see Preventing Ulcerative Colitis with Diet).

The toxic effects of hydrogen sulfide appear to be a result of blocking the ability of the cells lining our colon from utilizing butyrate, which is what our good bacteria make from the fiber and resistant starch we eat. It's like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, researchers were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

There are two ways hydrogen sulfide can be produced, though. It's mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, but the rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since they're forbidden from organic fruits and beverages by law.

More than 35 years ago, studies started implicating sulfur dioxide preservatives in the exacerbation of asthma. This so-called "sulfite-sensitivity" seems to affect only about 1 in 2,000 people, so I recommended those with asthma avoid it, but otherwise I considered the preservative harmless. I am now not so sure, and advise people to avoid it when possible.

Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than a hundred thousand women for over 25 years, researchers concluded cruciferous vegetables were not associated with elevated colitis risk.

Because of animal protein and processed food intake, the standard American diet may contain five or six times more sulfur than a diet centered around unprocessed plant foods. This may help explain the rarity of inflammatory bowel disease among those eating traditional whole food, plant-based diets.

How could companies just add things like sulfur dioxide to foods without adequate safety testing? See Who Determines if Food Additives are Safe? For other additives that may be a problem, see Titanium Dioxide & Inflammatory Bowel Disease and Is Carrageenan Safe?

More on this epic fermentation battle in our gut in Stool pH and Colon Cancer.

Does the sulfur-containing amino acid methionine sound familiar? You may remember it from such hits as Starving Cancer with Methionine Restriction and Methionine Restriction as a Life Extension Strategy.

These short-chain fatty acids released by our good bacteria when we eat fiber and resistant starches are what may be behind the second meal effect: Beans and the Second Meal Effect.

I mentioned ulcerative colitis. What about the other inflammatory bowel disease Crohn's? See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease.

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

What Animal Protein Does in Your Colon

What Animal Protein Does in Your Colon.jpeg

There's a take-off of the industry slogan, "Beef: It's What's For Dinner" - "Beef: It's What's Rotting in Your Colon." I saw this on a shirt once with some friends and I was such the party pooper--no pun intended--explaining to everyone that meat is fully digested in the small intestine, and never makes it down into the colon. It's no fun hanging out with biology geeks.

But I was wrong!

It's been estimated that with a typical Western diet, up to 12 grams of protein can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction process can be toxic.

It's generally accepted that carbohydrate fermentation--the fiber and resistant starches that reach our colon--results in beneficial effects because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental. Protein fermentation mainly occurs in the lower end of colon and results in the production of potentially toxic metabolites. That may be why colorectal cancer and ulcerative colitis tends to happen lower down--because that's where the protein is putrefying.

Probably the simplest strategy to reduce the potential harm of protein fermentation is to reduce dietary protein intake. But the accumulation of these toxic byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. In my video, Bowel Wars: Hydrogen Sulfide vs. Butyrate, you can see a study out of Australia showed that if you give people foods containing resistant starch you can block the accumulation of potentially harmful byproducts of protein metabolism. Resistant starch is resistant to small intestine digestion and so it makes it down to our colon where it can feed our good bacteria. Resistant starch is found in cooked beans, split peas, chickpeas, lentils, raw oatmeal, and cooled cooked pasta (like macaroni salad). Apparently, the more starch that ends up in the colon, the less ammonia that is produced.

Of course, there's protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon. Hydrogen sulfide is the rotten egg gas that may play a role in the development of the inflammatory bowel disease, ulcerative colitis (see Preventing Ulcerative Colitis with Diet).

The toxic effects of hydrogen sulfide appear to be a result of blocking the ability of the cells lining our colon from utilizing butyrate, which is what our good bacteria make from the fiber and resistant starch we eat. It's like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, researchers were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

There are two ways hydrogen sulfide can be produced, though. It's mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, but the rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since they're forbidden from organic fruits and beverages by law.

More than 35 years ago, studies started implicating sulfur dioxide preservatives in the exacerbation of asthma. This so-called "sulfite-sensitivity" seems to affect only about 1 in 2,000 people, so I recommended those with asthma avoid it, but otherwise I considered the preservative harmless. I am now not so sure, and advise people to avoid it when possible.

Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than a hundred thousand women for over 25 years, researchers concluded cruciferous vegetables were not associated with elevated colitis risk.

Because of animal protein and processed food intake, the standard American diet may contain five or six times more sulfur than a diet centered around unprocessed plant foods. This may help explain the rarity of inflammatory bowel disease among those eating traditional whole food, plant-based diets.

How could companies just add things like sulfur dioxide to foods without adequate safety testing? See Who Determines if Food Additives are Safe? For other additives that may be a problem, see Titanium Dioxide & Inflammatory Bowel Disease and Is Carrageenan Safe?

More on this epic fermentation battle in our gut in Stool pH and Colon Cancer.

Does the sulfur-containing amino acid methionine sound familiar? You may remember it from such hits as Starving Cancer with Methionine Restriction and Methionine Restriction as a Life Extension Strategy.

These short-chain fatty acids released by our good bacteria when we eat fiber and resistant starches are what may be behind the second meal effect: Beans and the Second Meal Effect.

I mentioned ulcerative colitis. What about the other inflammatory bowel disease Crohn's? See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease.

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 to Prevent Ulcerative Colitis with Diet

Preventing Ulcerative Colitis with Diet.jpg

What has driven the dramatic increase in prevalence of the inflammatory bowel disease Crohn's disease in societies that rapidly westernized--a disease practically unknown just a century ago? What has changed in our internal and external environment that has led to the appearance of this horrible disease?

Japan suffered one of the most dramatic increases, and out of all the changing dietary components, animal protein appeared to be the strongest factor. There was an exponential increase in newly diagnosed Crohn's patients and daily animal protein intake, whereas the greater the vegetable protein, the fewer the cases of Crohn's, which is consistent with data showing a more plant-based diet may be successful in both preventing and treating Crohn's disease (See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease). But what about other inflammatory bowel diseases?

In the largest study of its kind, shown in my video Preventing Ulcerative Colitis with Diet, 60,000 people were followed for more than a decade. Researchers found that high total protein intake--specifically animal protein--was associated with a significantly increased risk of the other big inflammatory bowel disease, ulcerative colitis. It wasn't just protein in general, but the "association between high protein intake and inflammatory bowel disease risk was restricted to animal protein."Since World War II, animal protein intake has increased not only in Japan but also in all developed countries. This increase in animal protein consumption is thought to explain some of the increased incidence of inflammatory bowel disease in the second half of the 20th century.

Other studies found this as well, but why? What's the difference between animal protein and plant protein? Animal proteins tend to have more sulfur containing amino acids like methionine, which bacteria in our gut can turn into the toxic rotten egg smell gas, hydrogen sulfide. Emerging evidence suggests that sulfur compounds may play a role in the development of ulcerative colitis, a chronic inflammatory disease of the colon and rectum characterized by bloody diarrhea.

The first hint as to the importance of our gut flora was in the 1970's when "analysis of stools showed that their bulk was made up of mostly bacteria, not undigested material." We're pushing out trillions of bacteria a day and they just keep multiplying and multiplying. They do wonderful things for us like create the protective compound, butyrate, from the fiber we eat, but unfortunately, the bacteria may also elaborate toxic products from food residues such as hydrogen sulfide "in response to a high-meat diet."

Hydrogen sulfide is a bacterially derived cell poison that has been implicated in ulcerative colitis. We had always assumed that sulfide generation in the colon is driven by dietary components such as sulfur-containing amino acids, but we didn't know for sure until a study from Cambridge was published. Researchers had folks eat five different diets each with escalating meat contents from vegetarian all the way up to a steak each day. They found that the more meat one ate, the more sulfide; ten times more meat meant ten times more sulfide. They concluded that "dietary protein from meat is an important substrate for sulfide generation by bacteria in the human large intestine."

Hydrogen sulfide can then act as a free radical and damage our DNA at concentrations way below what our poor colon lining is exposed to on a routine basis, which may help explain why diets higher in meat and lower in fiber may produce so-called "fecal water" that causes about twice as much DNA damage. Fecal water is like when researchers make a tea from someone's stool.

The biology of sulfur in the human gut has escaped serious attention until recently. Previously it was just thought of as the rotten egg smell in malodorous gas, but the increase in sulfur compounds in response to a supplement of animal protein is not only of interest in the field of flatology--that is, the formal study of farts--but may also be of importance in the development of ulcerative colitis.

I have several videos on our microbiome, including:

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: illustrator © 123RF.com. This image has been modified.

Original Link

How to Prevent Ulcerative Colitis with Diet

Preventing Ulcerative Colitis with Diet.jpg

What has driven the dramatic increase in prevalence of the inflammatory bowel disease Crohn's disease in societies that rapidly westernized--a disease practically unknown just a century ago? What has changed in our internal and external environment that has led to the appearance of this horrible disease?

Japan suffered one of the most dramatic increases, and out of all the changing dietary components, animal protein appeared to be the strongest factor. There was an exponential increase in newly diagnosed Crohn's patients and daily animal protein intake, whereas the greater the vegetable protein, the fewer the cases of Crohn's, which is consistent with data showing a more plant-based diet may be successful in both preventing and treating Crohn's disease (See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease). But what about other inflammatory bowel diseases?

In the largest study of its kind, shown in my video Preventing Ulcerative Colitis with Diet, 60,000 people were followed for more than a decade. Researchers found that high total protein intake--specifically animal protein--was associated with a significantly increased risk of the other big inflammatory bowel disease, ulcerative colitis. It wasn't just protein in general, but the "association between high protein intake and inflammatory bowel disease risk was restricted to animal protein."Since World War II, animal protein intake has increased not only in Japan but also in all developed countries. This increase in animal protein consumption is thought to explain some of the increased incidence of inflammatory bowel disease in the second half of the 20th century.

Other studies found this as well, but why? What's the difference between animal protein and plant protein? Animal proteins tend to have more sulfur containing amino acids like methionine, which bacteria in our gut can turn into the toxic rotten egg smell gas, hydrogen sulfide. Emerging evidence suggests that sulfur compounds may play a role in the development of ulcerative colitis, a chronic inflammatory disease of the colon and rectum characterized by bloody diarrhea.

The first hint as to the importance of our gut flora was in the 1970's when "analysis of stools showed that their bulk was made up of mostly bacteria, not undigested material." We're pushing out trillions of bacteria a day and they just keep multiplying and multiplying. They do wonderful things for us like create the protective compound, butyrate, from the fiber we eat, but unfortunately, the bacteria may also elaborate toxic products from food residues such as hydrogen sulfide "in response to a high-meat diet."

Hydrogen sulfide is a bacterially derived cell poison that has been implicated in ulcerative colitis. We had always assumed that sulfide generation in the colon is driven by dietary components such as sulfur-containing amino acids, but we didn't know for sure until a study from Cambridge was published. Researchers had folks eat five different diets each with escalating meat contents from vegetarian all the way up to a steak each day. They found that the more meat one ate, the more sulfide; ten times more meat meant ten times more sulfide. They concluded that "dietary protein from meat is an important substrate for sulfide generation by bacteria in the human large intestine."

Hydrogen sulfide can then act as a free radical and damage our DNA at concentrations way below what our poor colon lining is exposed to on a routine basis, which may help explain why diets higher in meat and lower in fiber may produce so-called "fecal water" that causes about twice as much DNA damage. Fecal water is like when researchers make a tea from someone's stool.

The biology of sulfur in the human gut has escaped serious attention until recently. Previously it was just thought of as the rotten egg smell in malodorous gas, but the increase in sulfur compounds in response to a supplement of animal protein is not only of interest in the field of flatology--that is, the formal study of farts--but may also be of importance in the development of ulcerative colitis.

I have several videos on our microbiome, including:

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: illustrator © 123RF.com. This image has been modified.

Original Link

How to Mitigate and Prevent Crohn’s Disease with Diet

NF-Sept20 Preventing Crohn's Disease With Diet.jpeg

Crohn's disease is an autoimmune disorder that affects more than a million Americans. It is an inflammatory bowel disease in which the body attacks the intestines. There is currently no known cure for Crohn's disease; current research focuses on controlling symptoms. There is no definitive medical or surgical therapy. The best we have is a plant-based diet, which has afforded the best relapse prevention to date.

Researchers got the idea to try a plant-based diet because diets rich in animal protein and animal fat have been found to cause a decrease in beneficial bacteria in the intestine. So, researchers designed a semi-vegetarian diet to counter that, and 100 percent of subjects stayed in remission the first year and 92 percent the second year. These results are far better than those obtained by current drugs, including new "biological agents" that can cost $40,000 a year, and can cause progressive multifocal leukoencephalopathy, a disabling and deadly brain disease. And a healthy diet appears to work better.

But what about preventing Crohn's disease in the first place? A systematic review of the scientific literature on dietary intake and the risk of developing inflammatory bowel disease found that a high intake of fats and meat was associated with an increased risk of Crohn's disease as well as ulcerative colitis, whereas high fiber and fruit intakes were associated with decreased risk of Crohn's.

These results were supported more recently by the Harvard Nurse's Health Study. Data revealed that long-term intake of dietary fiber, particularly from fruit, was associated with lower risk of Crohn's disease. Women who fell into in the highest long-term fiber consumption group had a 40 percent reduced risk, leading the accompanying editorial to conclude, "advocating for a high-fiber diet may ultimately reduce the incidence of Crohn's disease."

The irony is that the highest fiber group wasn't even eating the official recommended daily minimum of fiber intake. Apparently, even just being less fiber deficient has a wide range of benefits, including a significant reduction in the risk of developing Crohn's disease, but why? The authors suggest it's because "fiber plays a vital role in the maintenance of our intestinal barrier function."

Our skin keeps the outside world outside, and so does the lining of our gut, but in Crohn's disease, this barrier function is impaired. You can see this under an electron microscope as shown in my video Preventing Crohn's Disease With Diet. The tight junctions between the intestinal cells have all sorts of little holes and breaks. The thought is that the increase in prevalence of inflammatory bowel diseases may be that dietary changes lead to the breakdown of our intestinal barrier, potentially allowing the penetration of bacteria into our gut wall, which our body then attacks, triggering the inflammation.

We know fiber acts as a prebiotic in our colon (large intestine), feeding our good bacteria, but what does fiber do in our small intestine where Crohn's often starts? We didn't know, until a landmark study was published. Researchers wanted to find out what could stop Crohn's associated invasive bacteria from tunneling into the gut wall. They found the invasion is inhibited by the presence of certain soluble plant fibers, such as from plantains and broccoli at the kinds of concentrations one might expect after eating them. They wondered if that may explain why plantain-loving populations have lower levels of inflammatory bowel disease. But, the researchers also found that there was something in processed foods that facilitated the invasion of the bacteria. Polysorbate 80 was one of them, found predominantly in ice cream, but also found in Crisco, Cool Whip, condiments, cottage cheese--you just have to read the labels.

What about maltodextrin, which is found in artificial sweeteners like Splenda, snack foods, salad dressings, and fiber supplements? Maltodextrin markedly enhanced the ability of the bacteria to glob onto our intestinal cells, though other additives. Carboxy-methyl cellulose and xanthan gum appeared to have no adverse effects.

This may all help solve the mystery of the increasing prevalence of Crohn's disease in developed nations, where we're eating less fiber-containing whole plant foods and more processed foods. What we need now are interventional studies to see if boosting fiber intake and avoiding these food additives can be effective in preventing and treating Crohn's disease. But until then, what do we tell people? The available evidence points to a diet low in animal fat, with lots of soluble fiber containing plant foods, and avoiding processed fatty foods that contain these emulsifiers. We also want to make sure we're not ingesting traces of dishwashing detergent, which could have the same effect, so make sure to rinse your dishes well. Researchers found that some people wash dishes and then just leave them to dry without rinsing, which is probably not a good idea. We don't currently have studies that show that avoiding polysorbate 80 and rinsing dishes well actually helps. Nevertheless, advice based on 'best available evidence' is better than no advice at all.

Here's a video about using a more plant-based diet to reduce the risk of relapses: Dietary Treatment of Crohn's Disease.

I get a lot of questions about additives like polysorbate 80. I'm glad I was finally able to do a blog about it. Here are some videos on some others:

If you, like me, used to think all fiber was good for was helping with bowel regularity you'll be amazed! See for example, Dr. Burkitt's F-Word Diet.

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: Graphic Stock

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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

Original Link

Our Immune System Uses Plants To Activate Gut Protection

NF-Sep30 Why Broccoli is Crucial to Helping Our Immune System.jpg

It might seem that our skin is the first line of defense between our insides and the outside world, but our greatest interface with our environment is actually through the lining of our intestines, which covers thousands of square feet. And all that separates our gut from the outer world is a single layer of cells, 50 millionth of a meter thick - less than the thickness of a sheet of paper.

Compare that to our skin. In the video, The Broccoli Receptor: Our First Line of Defense, you can see a layer of skin, dozens of protective cells thick, to keep the outside world outside of our bodies. Why don't we have multiple layers in our gut wall? Because we need to absorb stuff from food into our body. It's a good idea for our skin to be waterproof, so we don't start leaking, but the lining of our gut has to allow for the absorption of fluids and nutrients.

With such a thin, fragile layer between our sterile core and outer chaos, we better have quite a defense system in place. Indeed, that's where "intraepithelial lymphocytes" come in.

Intraepithelial lymphocytes serve two functions: they condition and repair that thin barrier, and they provide a front-line defense against intestinal pathogens. These critical cells are covered with Ah receptors. Ah receptors are like locks, and for decades researchers have been searching for a natural key to fit in these locks to activate those receptors and sustain our immunity. We recently discovered a key: broccoli.

Cruciferous vegetables--broccoli, kale, cauliflower, cabbage, Brussels sprouts--contain a phytonutrient that is transformed by our stomach acid into the key that fits into the Ah receptor, stimulating our intraepithelial lymphocytes. In other words, broccoli leads to the activation of our immune foot soldiers.

In an editorial about Ah receptors and diet, researcher Lora V. Hooper from the Howard Hughes Medical Institute noted, "From childhood we learn that vegetables are good for us, and most of us eat our veggies without giving much thought to the evidence behind this accepted wisdom or to the mechanisms underlying the purported health-boosting properties of a vegetable-rich diet." But now we know that "specific dietary compounds found at high levels in cruciferous vegetables such as broccoli, cauliflower, and cabbage are essential for sustaining intestinal immune function." Green vegetables are in fact required to maintain a large population of those protective intraepithelial lymphocytes.

Maybe that's why vegetable intake is associated with lower risk of inflammatory bowel diseases such as ulcerative colitis, whereas the more meaty Western diet is associated with higher risk of inflammatory bowel diseases. This may be because the activating receptors on our intestinal immune cells are basically sensors of plant-derived phytochemicals.

This raises a broader question: Why did our immune system evolve this requirement for broccoli and other plant foods? Well, when do we need to boost our intestinal defenses the most? When we eat! That's when we may be ingesting pathogens. Linking heightened intestinal immune activation to food intake could serve to bolster immunity precisely when it is needed. At the same time, this would allow energy to be conserved in times of food scarcity, since maintaining these defenses takes considerable amounts of energy. Why remain at red alert 24 hours a day when we eat only a couple of times a day? We evolved for millions of years eating mostly weeds--wild plants, dark green leafy vegetables (or as they were known back then, leaves). By using veggies as a signal to upkeep our immune system, our bodies may be bolstering our immune defenses when we most need them. Thus, the old recommendation to "eat your veggies" has a strong molecular basis. (Did we really evolve eating that many plant foods? See my video Paleolithic Lessons).

This discovery has been all exciting for the drug companies who are looking into Ah receptor active pharmaceuticals. "However," as one research team at Cambridge concluded, "rather than developing additional anti-inflammatory drugs, changing diets which are currently highly processed and low in vegetable content, may be a more cost effective way towards health and well-being."

As remarkable as this story is, it is just the tip of the cruciferous iceberg! See, for example:

How else can we protect our immune function? Exercise (Preserving Immune Function In Athletes With Nutritional Yeast) and sleep (Sleep & Immunity)!

Given the variety and flexibility of most mammalian diets, a specific dependence on cruciferous vegetables for optimal intestinal immune function would seem overly restrictive, no? I address that in my video, Counteracting the Effects of Dioxins

-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, and From Table to Able.

Images thank to Nomadic Lass / Flickr.

Original Link