Man enjoying his burrito

Man “enjoying” his bean burrito


Today I’m going to talk about some dietary changes that may offer some of you symptom relief from your gastrointestinal issues. This is not a cure for small intestinal bacterial overgrowth or inflammatory bowel diseases like Crohn’s disease or ulcerative colitis. These disorders will require reducing gut pathogens and/or overgrowth of fungus like Candida albicans by a combination of antibiotics and antifungals while simultaneously replenishing beneficial gut flora in the gastrointestinal tract.

Nevertheless, there will be a certain percentage of you who will experience substantial symptom relief and perhaps complete resolution of your pain and bloating by eliminating these foods. It’s impossible to tell beforehand who will, and will not, experience this. Everyone is different after all.

One important warning needs to be mentioned before I get started. Many serious diseases like diabetes, thyroid disorders, cancers or obstructions of the small and large intestine often mimic the symptoms of irritable bowel syndrome. Reading this blog should not be considered an excuse to avoid a full exam by a qualified physician if you’re ill. There are way too many people out there foolishly playing the online self-diagnosis game without seeing a doctor. Don’t be one of them.

What I’m going to cover today is based on a research paper from the medical department of Monash University in Australia. It was published in 2010 and is entitled Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. (1) This dietary protocol involves eliminating foods that are most likely to be fermented by gut bacteria into gas.

The expansion of gas against the walls of the GI tract, mainly in the last section of the small intestine (ileum) and colon, is a major cause of pain and discomfort in those suffering from bowel disorders. It is also a reason inflammation, apart from bacterial infection and yeast overgrowth, continues to rage in the gut.

This is important, because inflammation is not a desirable environment for beneficial bacteria to thrive in. It is, however, a great environment for gram-negative gut pathogens like E. coli, Vibrio, Klebsiella or Shingella. Taming inflammation is a necessary step in healing your gut and fostering the recolonization of your gastrointestinal tract with beneficial gut flora like lactobacillus and bifidobacteria species.

FODMAP stands for fermentable Oligo-, Di- and Mono-saccharides and Polyols. The saccharides in this group are short-chain carbohydrates. Polyols are sugar alcohols. The saccharides include fructose, lactose, fructo- and galacto-oligosaccharides (fructans and galactins). The polyols are sorbitol, mannitol, xylitol and malitol.

All these carbohydrates have several things in common:

  • They are poorly absorbed by the small intestine.
  • They are small molecules and tend to have a laxative effect that in large quantities can promote diarrhea.
  • They are all rapidly fermented by bacteria creating gas as a byproduct

I want to interject here that gas is not normally a problem if you can expel it. Well, let me clarify that. While it will likely not lead to painful bloating, it may cause your significant other, family members or co-workers to give you and your gaseous emissions a very wide berth.

However, combining lots of gas with a paralyzed gut is where the real “fun” begins. Once gas becomes trapped, it causes gastrointestinal and stomach distension, which can be quite painful.

Usually this requires not only fermentable material reaching the colon, but also the ingestion of dietary opioids from either gluten grains and/or dairy opioids derived from A1 beta-casein. How susceptible you are to dietary opioids is dependent on genetics and on how many of them are formed by the quantity of gluten and A1 dairy you consume.

So for example, following a meal containing lots of easily fermentable veggies with a scoop of A1 casein ice cream and some cake or pie (or OxyContin) is not a good idea if painful bloating is an issue for you. And if you eat lots of whole-wheat, the fructans this contains, along with loads of indigestible fiber and gluten opioids will likely cause you to develop a profile resembling that of a pregnant woman in her fifth month. Stretchy pants anyone?

OK, let’s look at some common foods that cause many people problems. In order to get relief, most of the foods that follow need to be eliminated from your diet with one important exception that I’ll detail below.


Fructose comprises half of table sugar and occurs in various percentages in high-fructose corn syrup. Fructose is most easily absorbed in the small intestine when eaten with an equal quantity of glucose. Sugar, being 50% glucose and 50% fructose, is not likely to cause any problems unlike watermelon, which has nearly twice as much fructose as glucose.

Fructose that is not absorbed in the small intestine quickly makes its way to the colon where it is set upon by colonic bacteria that produce copious gas as a result. This assumes, of course, that it doesn’t cause diarrhea first, which is a very real possibility when ingesting lots of fructose at one go. Not everyone has problems digesting fructose, but if you are having digestive issues, especially diarrhea and gas, I would highly recommend eliminating the following high-fructose foods from your diet:

  • apples
  • pears
  • nashi pear (aka: Asian pear, Chinese pear, Korean pear, Japanese pear, Taiwan pear, sand pear, apple pear)
  • clingstone peaches
  • mango
  • sugar snap peas
  • watermelon
  • tinned fruit in natural juice
  • honey
  • agave syrup
  • high fructose corn syrup
  • large quantities of fruit
  • dried fruit
  • fruit juice

Low fructose sources that are good substitutes include:

  • banana
  • blueberry
  • durian
  • starfruit
  • grapefruit
  • grape
  • honeydew melon
  • kiwi
  • lemon
  • lime
  • mandarin orange
  • passion fruit
  • papaya
  • raspberry
  • cantaloupe
  • strawberry
  • tangelo

Honey substitutes:

  • maple syrup (real maple syrup is about 75% glucose and 25% fructose and a safe sweetener to use by most people who have fructose intolerance issues)


Lactose is the sugar in the milk of cows, sheep and goats. In order to digest lactose properly, you need a healthy small intestinal brush border capable of producing an enzyme called lactase that reduces this sugar to glucose and galactose.

If you don’t produce this enzyme–a very common occurrence in those with small intestinal bacterial overgrowth, celiac disease, the gluten intolerant, various ethnic groups and people who eat very little dairy–then lactose ends up in the colon where gut flora ferments it. If the lactose is from an A1 casein milk source, then bloating is a likely outcome as the opioid formed from this type of milk protein will slow intestinal movement.

Foods that are high in lactose include:

  • milk from cow, goat and sheep (regular & low-fat, both A1 and A2 casein milk)
  • ice cream
  • many non-cultured commercial yogurts (regular & low-fat)
  • soft and fresh cheeses like ricotta, cottage, string cheese, mozzarella, mascarpone and processed cheeses

Foods that are low in lactose include:

  • lactose-free milk
  • hard cheeses like Parmesan, cheddar; but also cultured cheeses like brie, Camembert, blue cheese
  • lactose-free yogurt
  • live-cultured yogurt
  • live-cultured kefir
  • gelato
  • sorbet
  • butter (European and cultured butter are lowest)
  • real cream
  • cultured sour cream
  • cultured buttermilk

There are products on the market like Lactaid® that can help in situations where lactose can’t be avoided or when you suspect a hidden source in prepared food. These supplements need to be taken before eating to have any beneficial effect. Just be aware that Lactaid® will do nothing about the gut-paralyzing effects of dairy opioids.

Oligosaccharides (fructans and/or galactans)

These are linear or branched fructose polymers. They are how carbohydrates are stored in a variety of vegetables, fruits and cereals. Because we lack the enzymes necessary to break these fructose-to-fructose bonds, we can’t absorb them at all. They end up in the colon where bacteria happily ferment them.

Foods high in oligosaccharides include:

  • artichokes
  • Jerusalem artichokes
  • asparagus
  • beets
  • Brussels sprouts
  • broccoli
  • cabbage
  • sauerkraut
  • fennel
  • garlic
  • leeks
  • okra
  • onions
  • scallions (white part)
  • peas
  • shallots
  • chicory
  • wheat & rye
  • legumes (chickpeas, lentils, red kidney beans, baked beans, black beans, navy beans, white beans, pinto beans, all beans)
  • watermelon
  • custard apple
  • white peaches
  • rambutan
  • persimmon

Foods low in oligosaccharides include:

  • bamboo shoots
  • bok choy
  • carrot
  • celery
  • corn
  • chayote (mirliton, choko, pear squash)
  • choy sum
  • eggplant
  • green beans
  • lettuce
  • chives
  • parsnip
  • pumpkin
  • chard
  • scallion (green part)
  • tomato
  • gluten-free breads or cereals

Of these foods, wheat is by far the major source of fructans in the typical Western diet. So you can add fructans to the list of reasons to avoid these grains.

When cooked, many of these foods become easier to digest, but many will still cause gas, especially legumes. Inulin and fructo-oligosaccharides, as found in prebiotics, are also fructans and will cause gas to be produced as they are fermented by beneficial bifidobacteria in the colon.

However, eliminating these foods has the unfortunate result of reducing beneficial colonic gut flora populations. As the researchers who devised FODMAP caution:

“Restrictions in FODMAP intake might potentially have a down side. It does mean restriction of dietary components with prebiotic effects. This might potentially be detrimental to large bowel health (such as the promotion of colerectal carcinogenesis), although no studies have addressed this issue to date.”

Remove the weasel words “might” and “potentially” and you have a more accurate description of what is likely to happen if you cut these foods entirely from you diet. In a recent study of 19 children suffering from Crohn’s disease, all children were found to have higher levels of gram-negative bacteria in their feces. (2)  This finding is consistent with other studies showing the same overgrowth of gram-negative pathogens in the colons of those afflicted with ulcerative colitis. (3) (4) Ulcerative colitis, by the way, is an important risk factor for colon cancer.

It will be next to impossible to overcome Crohn’s disease or ulcerative colitis without healthy colonies of bifidobacteria in the colon, not to mention prevent endotoxemia or many other illnesses. So what should you do?

Unfortunately, there is no way you can control the quantity of oligosaccharides you eat from whole foods. Amounts vary from food to food due mainly to differences in growing conditions and time since harvest. Unless you have a lab in your house to detect oligosaccharide content in vegetables and fruit, there’s no way to know beforehand how much gas and discomfort you’re likely to experience.

The safest way to keep these soluble fibers in your diet is in a supplement form like inulinFOS or xos/gos prebiotics. Why? Because that way you can take just enough to feed friendly bacteria, but not enough to cause painful gas. With a powder or supplement you’ll know precisely the amount you’re getting. If one scoop causes you gas problems, then reduce it by half. And if that causes you issues, then cut the dose again.

At the very least, you haven’t entirely cut these beneficial fibers out of your diet. You’ll encourage the growth of bifidobacteria which will help crowd out gram-negative pathogens in the colon.  It will also help establish beneficial bacteria that you swallow in a probiotic. You may wake up one day and pleasantly find that you can now tolerate more oligosaccharides from whole foods because colonies of gram-negative pathogens have been reduced and are no longer causing you gut issues.


Polyols are sugar alcohols that are found naturally in foods and are used as sweeteners in processed food, especially diet food. Longer-chain polyols are not well absorbed, or absorbed at all, in the small intestine so they end up in the colon where, once again, bacteria ferment them into gas.

Foods high in polyols include:

  • apples
  • apricots
  • cherries
  • longon
  • lychee
  • nashi pears
  • pears
  • nectarine
  • peaches
  • plums
  • prunes
  • watermelon
  • avocado
  • cauliflower
  • mushrooms
  • snow peas
  • sweeteners containing sorbitol, mannitol, xylitol, maltitol, isomalt and other sweeteners ending in “-ol”. Truvia is a brand of stevia extract that also contains polyols

Foods low in polyols:

  • banana
  • blueberry
  • starfruit
  • durian
  • grapefruit
  • grape
  • honeydew melon
  • kiwi
  • lemon
  • lime
  • oranges
  • passion fruit
  • papaya
  • raspberry
  • sweeteners like sugar, honey and maple syrup

Is it any wonder so many people avoid eating vegetables and fruits? And the recommendation to replace refined grains in the diet with their whole-grain varieties loaded with gut-destroying insoluble fiber only adds to the misery.

For many of you out there suffering from gut discomfort, the safest veggies or grains to eat are going to be peeled, cooked tubers (potatoes, sweet potatoes, yams, taro, parsnip, yuca, etc) and white rice.



Gibson P. R. and Shepherd S. J. (2010) Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 25: 252-258.


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