Low FODMAP diet may help reduce IBS symptoms
FODMAP is an acronym for "Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols". These are short-chain carbohydrates (typically sugars) that when incompletely absorbed in the gastrointestinal tract can be easily fermented by bacteria. Hence it may exacerbate the problems of IBS (irritable bowels syndrome) causing bloating, gas, and diarrhea. By avoiding these foods, people with IBS may experience some relief of symptoms.
There is a nice chart on ibsgroup.org of what foods are high in FODMAPs and which are acceptable.
Note that many of the foods that are high in FODMAPs are quite healthy and nutritious otherwise. FODMAP foods do not necessarily cause IBS. So if you do not have IBS and find that you can tolerate these food well without problematic symptoms, then there is no need to avoid them.
The list is mainly for people who are in pain from IBS and who may want to try eliminating these foods to see if it reduces the pain. IBS symptoms include chronic abdominal pain, discomfort, bloating, and irregular bowel habits.
What exactly are FODMAPs
FODMAP foods are ones that are high in ...
- oligosaccharides - these are fructans and galactans. Fructans are in certain vegetables such as asparagus, broccoli, brusssels sprouts, cabbage. Bread and pasta contains fructans. Galactans are in certain beans and lentils.
- disaccharides - these are lactose as in dairy products such as milk
- monosaccharides - these are fructose. Fructose is found in fruits such as in apples. It is found in some sweeteners, both artificial and natural (honey is one).
- polyols - these are sugar alcohols. They are found in some fruits (such as avocado, cherry, peach, etc) and some vegetables (cauliflower, green pepper, mushrooms). They are also found in many sweeteners.
The way to remember these technical names is that saccharides means sugar in Greek. Mono means "one". Monosaccharides are the simplest form of sugars. Di means two. Disaccharides are two monosaccharides combined together. Oligo means a few. Oligosaccharides are sugar polymers containing a few component sugars.
Fructo-oligosaccharides (FOS) contains short chains of fructose molecules. Galacto-oligosaccharides (GOS) contains short chains of glucose molecules. Beans for example contains the raffinose family of oligosaccharides that causes digestive gas because our bodies do not have the alpha-galactosidase enzyme to break down this type of sugar.
Such a long list of foods and many of which are part of a healthy diet. What can one eat instead?
According to the chart, here are some foods that acceptable on a low-FODMAP diet ...
- Certain fruits including banana, blueberries, orange, kiwi, cantelouple, grape, strawberry and others.
- Certain vegetables such as bok choy, carrot, celery, sweet potato, tomato, yam, zucchini, and other.
- Gluten-free bread, rice, oats, quinoa.
- Lactose-free milk, soy milk, lactose-free, sorbet.
Note that red bell peppers are on the acceptable list. But green bell peppers are on the avoid list. Keep in mind that the cut-off line is vague as to what is considered high-FODMAP and what is acceptable FODMAP amounts. It can differ depending on the reference source.
Why some fruit appears to be okay and others not depends on the ratio of fructose to glucose. A 1:1 ratio is probably okay to many people. But a higher fructose to glucose means a greater chance of being problematic.
Because a low-FODMAP diet eliminates many foods with high nutrition, it is necessary to consume enough of the other acceptable foods in order to make sure the diet is nutritionally adequate. For example, eat enough of the acceptable low fructose fruits. Eat enough brown rice and other acceptable vegetables for some fiber.
Low FODMAP diet is highly individualized
Depending on the individual and the severity of IBS, it may not be necessary to eliminate all the FODMAP foods completely. The amount and the type of food consume matters. So a person may be fine eating an apple by itself. But may not be when eating an apple along with a dish containing broccoli together. Both apple and broccoli are on the high FODMAP list.
One person may have no problems with apples, but problems with milk. Another person may be the exact reverse. Some may find that wheat, onions, apples, and pears are the most problematic. But others may not.
For some who are only lactose-intolerant, elimination of only lactose may be enough. There is a hydrogen breath test that can determine lactose-intolerance. For those who do not have lactose intolerance, they can safely consume lactose. But then they may or may not have problems with the other oligosaccharides.
People who do not have enough of the lactase enzyme will be lactose-intolerant. Whereas, people without enough hydrolases in the small intestine to break the fructose-fructose bond would be intolerant to oligosaccharides.
Then for others, it may require near total elimination to see any beneficial effect. So it gets complicated and people with IBS should work with a trained dietitian to eliminate not all FODMAP foods, but only those foods that one is particularly intolerant to.
The ironic thing is that FODMAP may be due to imbalance of gut flora, and eating fibers and fruits and vegetables (some of which are FODMAP foods) is supposed to balance and improve the gut flora over the long run because fiber is the food for the good bacteria as well.
On a Chris Kresser podcast, he says ...
"All prebiotics are FODMAPs, so when you’re on a low FODMAP diet, you’re avoiding prebiotics, but the thing is, prebiotics are what have the most profound effect on the gut flora over time. So, if you always avoid prebiotics and you don’t make any effort to work them back into your diet even at low levels, then you might feel better for as long as you avoid those foods, but you may never regain your ability to eat those foods because the changes in the gut microbiota are what led to that inability in the first place."
But the good thing is that FODMAP sensitivity can go away, unlike gluten sensitivity. So it might help to not avoid FODMAPs entirely, but work them back slowly into one's diet up to one's individual tolerance.
Further reading on the low-fodmap diet
For Cassandra Forsythe, eliminating FODMAP foods certainly helped, which she blogged about on her site about fitness and nutrition.
Besides anecdotal evidence, there is also clinical evidence of the effectiveness of the low-FODMAP approach to gut issues. Paper by Gibson and Shepherd concludes ...
"The low FODMAP diet provides an effective approach to the management of patients with functional gut symptoms. The evidence base is now sufficiently strong to recommend its widespread application."
The paper "Clinical Ramifications of Malabsorption of fructose and other short-chain carbohydrates" contains good technical information with more about the types of foods that are to be avoided.
In the book Digestive Health with Real Food, it writes ...
"Foods that contain a high fructose-to-glucose ratio (more than 0.5 grams of fructose in excess of glucose per 100-gram serving or more than three grams of fructose per serving) are considered FODMAPs"
Some of these are ...
Apples, boysenberries, cherries, figs, grapes, mango, pear, tamarillo, watermelon, artichoke, asparagus, sugar snap peas, agave -- just to name a few.