My nutrition student volunteer Isabella Gregov is back today with another post on fructose malabsorption. I highly recommend you go read her post Introduction to Fructose Malabsorption before reading this post. Fructose malabsorption is a very interesting topic and research about implementing a low-fructose diet is new. This post focuses on ways of implementing a low-fructose diet and how it differs from a low FODMAP diet.
Always talk to your doctor when experiencing digestive issues and work with a dietitian when making any significant dietary changes. This blog post is meant for general information, not individual health advice. If you are seeking individual advice from a dietitian please read my page on my Nutrition Counselling and Coaching Services.
If you are suffering from fructose malabsorption, the best-known way to manage your symptoms is by implementing a low-fructose diet. If you have just been introduced to specialized diets like the low-fructose diet, you may be wondering, “How much fructose can I eat???” or, “What’s the difference between a low-fructose diet and a low FODMAP diet? How do I know which is right for me?” All of these questions, and a few others you may have, will be answered in the following post!
What is a low-fructose diet?
To start off, a low-fructose diet involves eliminating and/or limiting foods that have a particularly high fructose content, such as honey, high-fructose corn syrup (glucose-fructose), and certain fruits.1 Low-fructose diets may be implemented to reduce and manage symptoms for those with severe fructose malabsorption. If you do not have fructose malabsorption, following a low-fructose diet is unnecessary. Many of the fruits and vegetables that are high in fructose are nutritious components of a well-balanced diet. A low-fructose diet is different from the low FODMAP diet, which will be discussed later in this post.
How is a low-fructose diet implemented?
Currently, there are no specific, established guidelines for implementing low-fructose diets.2 Two researchers from Georgia Regents University have developed a low-fructose diet plan that they have found to be helpful for reducing gastrointestinal symptoms in those with fructose malabsorption. 2 It follows the typical pattern of an elimination diet. To begin, patients follow a diet that is very low in fructose – about 5 g of fructose per day.2 This phase is called the ‘elimination phase’, and it lasts until the patient experiences relief from their symptoms, usually about 2 to 6 weeks.2 Once the elimination phase is complete, patients re-introduce foods of slightly increasing fructose content, one at a time.2 This is called the ‘re-introduction phase’.2 Its purpose is to determine how much fructose a particular individual can tolerate, allowing the individual to follow the least restrictive diet required to manage their fructose malabsorption symptoms.2
This is one example of how a low-fructose diet may be implemented. Do not make any dietary changes on your own without first consulting with your doctor and/or dietitian. Always follow the individualized advice of your doctor and dietitian over anything on the internet. It is important to note that fructose tolerance varies among individuals – personal adjustments, like those made in the ‘re-introduction phase’ described above, can make a low-fructose diet much easier to follow. If you think you are suffering from fructose malabsorption, or you have just been diagnosed, make sure that you seek the guidance of a dietitian before following a low-fructose diet.
As you learn more about fructose malabsorption, you may come across information about glucose tablets or consuming foods with a balance of glucose and fructose to manage symptoms. This information largely comes from a series of studies conducted in the 1980s and 90s, which provided evidence that consuming glucose along with fructose may prevent peaks in breath hydrogen levels4 (an observation that may be indicative of an intolerance to fructose) and/or improve gastrointestinal symptoms.3,5 Scientists explained these findings by suggesting that glucose increases the absorption of fructose.3,5
If you read my previous post, you would realize that improved fructose absorption means less fructose-related gastrointestinal symptoms. Simple, right? Unfortunately, the relationship between glucose-fructose balance and improved gastrointestinal symptoms is not as clear as previously thought. Current research suggests that consuming glucose supplements along with fructose does not increase the absorption of fructose, improve symptoms of fructose malabsorption, or decrease breath hydrogen levels.6,7 These findings, while in no way definitive, cloud the older findings. More research is needed to disprove and explain the older positive results. For now, it is advised that you do not consume excess glucose (for example, in the form of glucose tablets) in conjunction with high-fructose foods. Doing so adds extra sugar to the diet, and may have no effect on symptoms.7 Stick with a low-fructose diet – the science behind it is more clear!
What about a low FODMAP diet?
Another term that you may have come across is ‘low FODMAP’. However, a low FODMAP diet should not be confused with a low-fructose diet. While a low-fructose diet focuses on reducing fructose intake only, a low FODMAP diet limits various fermentable sugars.8 These sugars include fructose as well as fructans (essentially chains of fructose molecules), galacto-oligosaccharide (chains of galactose, a simple sugar), lactose (the sugar in milk), and polyols (sugar alcohols).8 The low FODMAP diet does not limit fructose as severely as a low fructose diet.2 It is designed for those with certain digestive disorders (e.g., IBS, IBD, etc.)8 while a low-fructose diet is designed for those with severe fructose malabsorption2. A low FODMAP diet is much more comprehensive than a low-fructose diet, and the two diets are used for treating different dietary problems.
The low FODMAP diet is much more commonly used than a low fructose diet, as it is more common for digestive symptoms to be triggered by multiple FODMAPs, not just fructose. If you have determined that fructose alone is likely causing your symptoms, then it may not necessary to implement a low FODMAP diet. Your dietitian may suggest a low-fructose diet instead. If your symptoms are not improved by the low-fructose diet, your dietitian may then recommend the low FODMAP diet.
One last question remains – how do you know if your symptoms are caused by fructose alone, or if they are caused by FODMAPs? A non-invasive way of starting to answer this question is to keep a food diary for at least a week and review it with the help of a dietitian. Some cellphone apps are now available which can be used for tracking food and symptoms, but are not capable of accurately identifying which foods are symptom triggers. Individuals may experience symptoms within a few hours of eating a food, or as long as 24-48 hours after eating.10 A dietitian can help you with identifying potential symptom triggers.
If you are noticing gastrointestinal symptoms after consuming foods high in fructose as well as other foods – for example, milk products and legumes – then your symptoms may be related to the wider range of FODMAPs. If you are only noticing symptoms after consuming foods high in fructose (like honey, glucose-fructose, and certain fruits), then it is may be more likely that you have fructose malabsorption. Your dietitian can help decide which diet is best for you to try.
Note: the low FODMAP diet and a low-fructose diet are not the only two diets which can be used by dietitians to help manage digestive symptoms.
As a final word of advice for those with fructose malabsorption, don’t get discouraged by the list of high-fructose foods! Experiencing relief from gastrointestinal symptoms is wonderful and invigorating. Adjusting your diet to your personal level of fructose tolerance makes following a low-fructose diet much easier. Your body will thank you for it!
Do you have questions about fructose malabsorption, low-fructose diets, FODMAPs, or other areas of nutrition or digestive health? Click here to learn more about Lauren’s nutrition services. Or you can ask her some general questions through her facebook page Lauren Renlund RD.
- Skoog, S. M. & Bharucha, A. E. (2004). Dietary fructose and gastrointestinal symptoms: A review. Retrieved from http://www.bashaar.org.il/files/101022005111814.pdf
- Fedewa, A., & Rao, S. S. (2014). Dietary fructose intolerance, fructan intolerance and FODMAPs. Current gastroenterology reports, 16(1), 1-8. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3934501/
- Ebert, K., & Witt, H. (2016). Fructose malabsorption. Molecular and cellular pediatrics, 3(1), 10. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755956/
- Truswell, A. S., Seach, J. M., & Thorburn, A. W. (1988). Incomplete absorption of pure fructose in healthy subjects and the facilitating effect of glucose. The American journal of clinical nutrition, 48(6), 1424-1430. Retrieved from http://ajcn.nutrition.org/content/48/6/1424.abstract
- Rumessen, J. J., & Gudmand-Høyer, E. (1986). Absorption capacity of fructose in healthy adults. Comparison with sucrose and its constituent monosaccharides. Gut, 27(10), 1161-1168. Retrieved from http://gut.bmj.com/content/gutjnl/27/10/1161.full.pdf
- Tuck, C. J., Ross, L. A., Gibson, P. R., Barrett, J. S., & Muir, J. G. (2017). Adding glucose to food and solutions to enhance fructose absorption is not effective in preventing fructose‐induced functional gastrointestinal symptoms: randomised controlled trials in patients with fructose malabsorption. Journal of Human Nutrition and Dietetics, 30(1), 73-82. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/jhn.12409/full
- Lacovou, M. (2016, Nov 21). Adding glucose to high FODMAP foods – Does it really help? Retrieved from http://fodmapmonash.blogspot.ca/2016/11/adding-glucose-to-high-fodmap-foods.html
- Canadian Digestive Health Foundation. (n.d.). Understanding FODMAPs. Retrieved from http://www.cdhf.ca/bank/document_en/32understanding-fodmaps-.pdf
- Sue Shepherd. (2017). Fructose Malabsorption. Retrieved from http://shepherdworks.com.au/disease-information/fructose-malabsorption
- Monash University (2016, June 20). Timing of symptoms. Retrieved from http://fodmapmonash.blogspot.ca/2016/06/timing-of-symptoms.html
About the Guest Author
Isabella Gregov is majoring in Applied Human Nutrition at the University of Guelph. She has first-hand experience living with various types of gastrointestinal problems and specialized diets. She is passionate about sharing her knowledge and experiences and helping others suffering from dietary complaints. Isabella hopes to earn her degree and complete an internship to become a Registered Dietitian.