Understanding your Results – FM

Fructose malabsorption is the inability to absorb sufficient amounts of the sugar fructose. If you don’t absorb sufficient amounts of fructose, it passes into your large intestine (colon) and may cause diarrhea, flatulence (gas) and abdominal pain.

Gut-chek for fructose malabsorption checks how much of the fructose is not absorbed in your small intestine but passes through into your colon. Bacteria in your colon exposed to fructose forms hydrogen and methane gas. We detect hydrogen and methane gas in the breath that forms originally in your colon.

Gut-chek for fructose intolerance consists of four breath collections. One collection is before we give you 25 grams fructose. We measure hydrogen, methane and carbon dioxide gas in all four tubes by gas chromatography.

The carbon dioxide gas level allows us to check if (a) the breath sample is valid and (b) normalizes the results in case the breath collection is not perfect.

We compare the hydrogen and methane levels in the 1-, 2- and 3-hour breath samples to the baseline (0 minute) sample. If any of the post-fructose samples contain 20 parts per million (ppm) hydrogen and methane gas above the baseline sample, you have fructose malabsorption.

What if I have a Positive Fructose Malabsorption Breath Test?

Limit the amount of foods in your diet that contain fructose

If your hydrogen breath test indicates fructose malabsorption, it would be best to avoid foods that are high in fructose.

The most common high-fructose foods include:

Food items with high fructose corn syrup


Dried fruits



Sweet drinks (especially sodas)

Sport drinks

Flavored water drinks

The fructose content is also high in many fruits such as:

Baked goods

Milk chocolate

Salad dressings and sauces

Instant oatmeal and cereal bars

Instant mashed potatoes, soups, rice and noodle mixes

Lunch meats


Pancake, biscuits and cookie mixes

If you are unsure if a food item contains enough fructose to cause a problem, try a small amount and wait to see how you feel. If you don’t feel any gastric distress after a few hours, you can consume small amounts of this food.

Spread fructose intake throughout the day

If you can stand some fructose in your diet, try to spread fructose foods throughout the day rather than ingest in one meal. Fructose malabsorption is an individual condition. What works best for some may not work for you. Try to reduce the intake of fructose foods. For example, if you like to eat apples, eat only half an apple.

Pick foods that have reduced fructose content

Replace fruits with high fructose content with fruits with a lower fructose content such as bananas, grapefruit, kiwi or strawberries.

Try eliminating probiotics

Fructose malabsorption is the excess production of gas by the bacteria in the intestinal tract. This is why adding probiotics can sometimes exacerbate your symptoms if you have fructose malabsorption. Eliminate your probiotics for a week to see if your symptoms reduce. It is suggested that bifidobacteria is probably the best probiotic choice because it doesn’t produce gas, unlike other types of bacteria.

Limit foods with high sugar levels

Many foods contain high sucrose levels (table sugar). Sucrose is a mixture of glucose and fructose. When the body digests sucrose, fructose is produced. Limit adding table sugar to foods and reduce sucrose containing foods in your diet.

Avoid foods with sugar alcohols

Sorbitol, a sweetener and is known as a sugar alcohol, becomes fructose when it’s digested. Sorbitol is used in diet drinks and sugar-free chewing gums. Read labels on food and beverages and avoid those food products containing sorbitol.

What if I have a Negative Fructose Malabsorption Breath Test?

If you have abdominal pain, bloating, flatulence or diarrhea when you eat fruit and food products with high amounts of fructose but received a negative fructose malabsorption breath test, there may be several reasons for this result.


You may not have fructose malabsorption but have an intolerance to FODMAPs. FODMAPs is an acronym for Fermentable Oligo-, Di-, and Mono-saccharides, and Polyols. Fructose is a monosaccharide. The other FODMAP components are typically found in fructose containing foods but not always. The disaccharides include lactose, the oligosaccharides include fructans and galactans, and the polyols contain sorbitol, mannitol, xylitol, and maltitol. Try using a FODMAP-free diet to see if your symptoms are reduced or eliminate. Please consult our Learning Center for additional FODMAP resources.


Your symptoms could also indicate that you have bacterial overgrowth. Consider taking the Gut-chek small intestinal bacterial overgrowth test.


5-10% of people do not produce hydrogen and methane gas. The bacteria in your intestine do not digest fructose to hydrogen or methane. The test will not be able to confirm fructose malabsorption. Try reducing fructose-containing items from your diet and see if your symptoms are reduced.

Please consult our Learning Center for additional resources.