Monosaccharides: The Simplest Sugars and Foundation of FODMAPs 

Monosaccharides, the ‘M’ in FODMAP, are the simplest form of carbohydrates and the building blocks of more complex sugars like fructans (which are a part of the ‘O’ in FODMAP, oligosaccharides) and lactose (a component of the ‘D’ in FODMAP, disaccharides). Glucose is our primary energy source for the body and is one of the key monosaccharides alongside fructose. Both glucose and fructose are monosaccharides that, when combined, make up the disaccharide sucrose (i.e., table sugar). These two compounds are quite unique – they have different chemical structures, have separate metabolic pathways, and are found in different foods as well. Chemistry aside, they are important building blocks and the body’s preferred energy source. Glucose is found in both healthy and unhealthy food options; however, fructose tends to be more of a villain when it comes to managing Irritable Bowel Disease (IBS) symptoms. 

Fructose in the Spotlight: A Monosaccharide and Potential FODMAP Culprit 

Unlike glucose, which is readily absorbed by the intestines, fructose absorption can be slower and less efficient, potentially leading to gut discomfort in sensitive individuals. While fructose can be found in fruits and some vegetables, it is found in larger quantities in items such as high-fructose corn syrup and sweet treats/desserts. According to the Mayo Clinic, fructose intolerance is a cluster of symptoms and can present as gas/gas pain, bloating, and diarrhea. 

The key to minimizing fructose-related symptoms is careful consideration of all food labels. One benefit of fructose-containing fruits and veggies is their high fiber profile. If you are going to have a source of fructose, a fruit or vegetable would be the ideal choice, as fiber can help slow down fructose absorption and reduce potential discomfort. 

Focusing on Whole Fruits: Natural Sugars vs. Added Sugars 

Since whole fruits and natural sugars tend to contain more fiber, it would be ideal for those experiencing IBS symptoms to stray away from added sugars.  See the table below from the University of Virginia Health System for foods to avoid and healthy swaps to consider:

If you are looking for more information and guidance, several apps are available. The Spoonful App is helpful at grocery stores, offering a barcode scanning feature to analyze foods on the spot. Additionally, the Monash University FODMAP Diet app provides easy-to-digest FODMAP information and is constantly being updated.

1. _{University of Virginia Health System. (n.d.). Low fructose diet. https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2023/12/Low-Fructose-2023.pdf} 
2. _{Zeratsky, K. (2024, January 9). Fructose intolerance: Which foods to avoid?. Mayo Clinic. https://www.mayoclinic.org/fructose-intolerance/expert-answers/faq-20058097}