Ouch!!! Why is that healthy low-fat, whole-wheat turkey sub I had for lunch fighting to get out?


This is the fifth post in the small intestinal bacterial overgrowth (SIBO) series. This and the next post deal with nutritional factors that predispose to SIBO. As I discussed here and here, there are a number of “non-dietary” causes of SIBO. Nevertheless, many of these diseases are clearly due to dietary factors, such as obesity, celiac disease and alcoholic and non-alcoholic liver disease. The lines are a bit blurred when determining what is or isn’t a dietary cause.

I will continue my general outline of dividing the causes of SIBO into the two main categories of compromised stomach barrier function and impaired intestinal motility. While I’m leaving out overt reference to immune system disorders like AIDS, these dietary factors are equally relevant to this group.

I was really hoping to cover both categories in a single post, but the reality is that this is too big a topic to cover without causing my readers to palm their puffy red eyeballs, shake their weary heads like a Looney-tunes cartoon character and run shrieking from their computer screen cursing my name to the high heavens!

So dear reader, out of courtesy to you, this post will concentrate only on dietary factors affecting stomach barrier function as well as gastroesophageal reflux disease or GERD. You’ll have to wait for the second installment for the rest of the story.

Gastric Barrier Dysfunction and GERD

The reason I want to include GERD in this post is that it encourages sufferers to take antacids and proton-pump inhibitors to seek relief from their symptoms. As we already know from part three, this predisposes to small intestinal infection. And many of the dietary causes of GERD overlap with the causes of SIBO.

I want to warn you that GERD, like SIBO, may be masking a far more serious medical condition like ulcers and cancer. If these dietary recommendations do not alleviate your acid reflux, you need to seek qualified medical attention.

So what dietary factors are screwing with your belly? Well, a short anatomy lesson is in order. I promise it won’t hurt too much.

The esophagus is an approximately 10-inch tube that transports food from the back of your throat (pharynx) down to your tummy. Like the intestines, nerve impulses in a healthy esophagus cause wave-like motions or peristalsis to propel food towards the stomach. I’m sure you all remember the sausage analogy I used to illuminate this. Keep this in mind for later reference.

As food approaches the end of this tube, it meets up with a valve called the esophageal sphincter. It opens and allows the food and drinks you’ve just ingested entry into the stomach. This valve closes after food has passed to keep the combination of partially digested food, drink and gastric juice, also known as chyme, from reentering the esophagus and causing heartburn and acid reflux. This is important because the lining of the esophagus is not meant to sustain the highly acidic contents from the stomach and repeated episodes of this causes inflammation (esophagitis) and damage. As chronic inflammation is at the root of cancer formation, this is obviously not a desirable long-term state of affairs.

Anatomy lesson over. See, that wasn’t so terrible now was it?

Now for the bad news. All alcohol consumption, even small amounts, relaxes the esophageal sphincter. Boo hiss! The more you drink, the more this is apt to happen. Double boo hiss!

Not all alcohol, however, is equally bad. Wine seems to have the least effect in causing acid reflux, hard liquor and beer more. So if you suffer from GERD, consider switching to wine as your drink of choice but–there’s that damn word again–even wine can still be an issue if you overdo it so drink in moderation. At the very least consider limiting all alcohol intake especially before bedtime, or you’re apt to revisit your dinner while in the midst of your favorite dream.

Also recall that small amounts of alcohol tend to improve barrier function by lowering stomach acid; however, this isn’t universally true for all alcohol. Fermented alcoholic beverages like red and white wine, beer, champagne and sherry do this the most but distilled alcoholic beverages like vodka, rum or scotch have no impact on stomach pH so their effect is neutral. It is possible that drinking small to moderate amounts of fermented alcoholic beverages likely helps protect against SIBO, at least SIBO caused from bacteria ingested with saliva or food. Of course, this all changes for the worse the more you drink increasing your risk of contracting SIBO, not to mention one hell of a hangover.

Stomach emptying is also stimulated by small quantities of alcohol but delayed with larger amounts. The reason is simple. Your stomach will not release partially digested food into the first section of the small intestine (the duodenum) until it’s sufficiently digested, which means less than 2mm in diameter. Raising stomach pH impairs this process causing your stomach to work harder and longer before releasing chyme.

As most of you well know, alcohol especially in large quantities, has a dampening effect on our nervous system. That’s why many of us drink it to unwind, relax and reduce feelings of anxiety when asking for the phone number of a hot number in a bar or club. Nevertheless, because of these nerve deadening effects, nerves responsible for peristalsis in the esophagus also chill out so you run the risk of diminishing this propulsive movement towards your tummy, turning what should be a one-way street into a two-way, vomit-strewn highway. This nerve suppressing effect affects the nerves responsible for stomach churning and emptying.

So couple all of this with a belly full of food, a delayed emptying of contents and a relaxed esophageal sphincter and you have the perfect cocktail (pun intended) for heartburn and acid reflux, especially when you go horizontal for the night–intentionally or not–and gravity is no longer your friend.

However, many of you reading this know that alcohol isn’t the only cause of GERD because either you don’t drink every day or at all. So what else could be causing it?

Another largely unrecognized dietary culprit is excess fiber, especially insoluble fiber from whole grains and beans. This is ironic given that we have been exhorted for decades to eat more and more of this stuff to supposedly “improve” our health.

Now I’m not talking about the normal quantities of fiber found naturally in fruits and vegetables. That’s perfectly fine and encouraged as long as it doesn’t cause you any undue gastrointestinal upset when it’s fermented in your colon. And even if it does, you can lessen the effects by peeling your fruit or trimming your veggies of their more fibrous components. So please don’t take this as an excuse not to eat your fruits and vegetables. If not for me, then eat them for your mother.

What I am talking about are the large quantities of insoluble fiber contained in whole grains and legumes. And it’s called insoluble for a reason. We do not produce the necessary enzymes to digest it nor can colonic bacteria break it down even though it tries by fermenting and fermenting and fermenting it in the colon producing tons of gas as a byproduct. Anyone remember that campfire scene from Blazing Saddles?

Fiber is the only substance you eat that expands 4 to 5 times its size when mixed with liquid. Pretty much the same thing that happens when you add milk to your whole-wheat cereal. When you eat a meal rich in insoluble fiber, it swells up in your stomach like a sponge when mixed with gastric juice. This is why fiber makes you feel so full. Because of this, many dietitians or weight-loss “experts” recommend it as a way to curb appetite.

But this has a very real downside to it. In your stomach, insoluble fiber forms large clumps taking your tummy longer to break it down before emptying. This swelling mass of food, along with whatever else you ate and drank with it, exerts upward pressure against your gastroesophageal sphincter leading to heartburn and acid reflux. Hence the picture of that poor man sitting behind his desk wondering why that “healthy” whole-wheat turkey sub is causing him so much grief.

For more on the destructive effects of too much dietary fiber on your GI tract, I highly recommend the book Fiber Menace by Konstantin Monastyrsky that you can find here. His informative website can be accessed here. So for all you GERD sufferers out there, another thing you need to do is limit fiber-rich foods like beans and whole grains, especially before bedtime.

Another huge, and I mean huge as in whale huge, dietary no-no is my favorite punching bag, gluten grains. It is of course an integral part of many of the aforementioned “healthy” fiber-rich whole grains not to mention the entire standard American or SAD diet. Gluten is a protein contained in wheat, barley, rye and sometimes oats if these oats are cross-contaminated in harvest or processing. The name gluten is derived from the Latin word for glue so make of that what you will.

Gluten has two substances that exert negative effects on stomach function.

The first was isolated back in the sixties when your dear blogger was still in diapers. That substance is adenosine. Adenosine has a number of properties that you can read about here, but what interests me most is its inhibiting effect on the nervous system including the enteric nervous system that regulates digestive muscle contractions and propulsive movement. Adenosine negatively impacts peristalsis everywhere along the GI tract including the esophagus. It no doubt slows both stomach contractions and the opening of the pyloric sphincter which is the valve that regulates the rate chyme enters the duodenum.

However, the gluten hootenanny doesn’t stop here.

Five separate opioid protein fragments or peptides are formed when gluten is digested: A4, A5, B4, B5 and C. All opioids slow digestive function regardless of whether they are derived from the opium plant or gluten grains. An opioid is an opioid is an opioid.

To what extent adenosine and gluten opioids slow digestive function no doubt depends upon the quantity and frequency of gluten consumption, the amount of indigestible fiber attached to it and the genetic susceptibility of the person doing the eating.

For me, nothing comes remotely close to causing acid reflux, heartburn and constipation as consuming gluten grains. Drastically limiting or eliminating gluten grain consumption should be the number-one dietary change to your diet if you suffer from GERD and SIBO.

I would be remiss if I didn’t mention that certain types of dairy also release an opioid fragment called A1 beta-casomorphin-7. It is prevalent in the milk of certain breeds like Holsteins and Friesians, but low or absent in the milk of Jersey and Guernsey cows, goats and Asian and African cattle. These latter animals have A2 casein in their milk and this type of casein does not form an opioid fragment when digested by humans. Casein is found in the protein part of milk but not the fat so butter and cream are largely casein free while cheese is casein rich. So you may need to rethink your dairy consumption or switch to A2 milk sources.

Personally I find I have no GI issues drinking 100% Jersey or goat milk. Moreover, I don’t have any issues with moderate amounts of casein-rich cheese now that I don’t eat gluten, but it may be different for you. For more on this subject read Devil in the Milk by Keith Woodford.

Another class of foods that commonly causes GERD are the nightshades: potatoes (not sweet potatoes or yams), tomatoes, all peppers (but not black pepper), eggplant, tomatillos, paprika, tamarios, pepinos, pimentos and cayenne. Some people are very sensitive to the irritating glycoalkoloids found in these foods so you may want to cut them out of your diet to see if it helps.

So here’s my recipe for the ultimate GERD experience. Consume a large meal containing lots of whole-wheat, add some beans, some very spicy tomato-salsa, perhaps a chunk or two of A1 beta-casein containing cheese, wash it all down with copious quantities of alcohol and immediately rush off to bed. In no time, you’ll be uttering those poetic words of endearment every spouse wants to hear: Honey, my acid reflux just stained the sheets. Magic, absolute magic!

There is one more dietary class of substances that is quite damaging to the stomach and digestive tract because of their physical, biological and gut flora disrupting properties. Those substances are plant lectins. Lectins are molecules that plants produce to protect themselves from bacteria, fungus and from being eaten by insects and animals like us. They are highly effective natural pesticides. The most studied lectins are from the legume family–beans and peanuts–and from wheat.

In rats fed raw kidney bean lectin, several unfavorable effects are observed that negatively impact gastric function. They strip away the protective mucous lining of the rat stomach, inhibit its repair and encourage the proliferation of H. pylori, the bacteria responsible for ulcers. H. pylori infection predisposes to SIBO because the inflammation it causes damages the acid secreting parietal cells and reduces stomach acid levels.

Now none of you reading this are ingesting raw kidney beans, or at least I hope not. Nevertheless, you are exposed to plant lectins at lower concentrations in your diet, especially if you consume lots of legumes and wheat. I will have more to say about lectins in the next post.



Bishop, H., Frazier A. C., Robinson G. B., Schneider R. (1963). The Nature of the Antiperistaltic Factor From Wheat Gluten. British Journal of Pharmacology, 21: 238-243.

Bujanda, L. M.D. (2000). The Effects of Alcohol Consumption Upon the Gastrointestinal Tract. The American Journal of Gastroenterology, 95(12): 3374-3382.

Fukudome S. and Yoshikawa M. (1991). Opioid peptides derived from wheat gluten: their isolation and characterization. Federation of European Biochemical Societies, 296: 107-111.

Fukudome S. and Yoshikawa M. (1992). A novel opioid peptide derived from wheat gluten. Federation of European Biochemical Societies, 316 (1): 17-19.

Gropper, S. R., Smith J. L., Groff J. L. (2009). Advanced Nutrition and Human Metabolism, Fifth Edition. Belmont, CA: Wadsworth Cengage Learning.

Hamid R. and Masood A. (2009) Dietary Lectins as Disease Causing Toxicants. Pakistan Journal of Nutrition, 8 (3) 293-303.

Huebner F. R., Lieberman K. W., Rubino R. P., Wall J. S., (1984). Demonstration of High Opioid-Like Activity in Isolated Peptides From Wheat Gluten Hydrolysates. Peptides, 5: 1139-1147.

Monastyrsky, K. (2005). Fiber Menace: The Truth About Fiber’s Role in Diet Failure, Constipation, Hemorrhoids, Irritable Bowel Syndrome, Ulcerative Colitis, Crohn’s Disease, and Colon Cancer. USA: Ageless Press.

Pusztai A., Ewen S.W.B., Grant G., et al. (1993). Antinutritive effects of wheat-germ agglutinin and other N-acetyglucosamine-specific lectins. British Journal of Nutrition, 70: 313-321.

Robinson G. B., Schneider R., Frazer A. C. (1964) A Substance From Wheat Gluten, Which Inhibits the Intestinal Peristaltic Reflex. Biochimica Et Biophysica Acta, 93: 143-149.

Woodford, K. B. (2007). Devil in the milk: illness, health and politics: A1 and A2 milk. Vermont: Chelsea Green Publishing.

Comments are closed.

Post Navigation