When I was diagnosed with fructose malabsorption, I asked myself if this was due to a change in my digestive system or whether I always had problems digesting fructose and my symptoms simply worsened. I thought back to my childhood and remembered a few possible connections. One, even when I was overall skinny, I always had a bloated belly; two, after I was switched from breastfeeding and put on formula, I had a horrible case of very loose diarrhea for several months – this is according to my mother and sorry if that was TMI; three, I was always craving food and thinking of my next meal, even when I just finished eating; and four, I would often get sick with high fevers. All of these examples could be completely separate and have no relation to my fructose malabsorption, but, maybe it did so I asked my gastroenterologist. He could not answer my question because we unfortunately do not have a good enough understanding of fructose malabsorption and many other digestive disorders. However, this did make me wonder, do babies and children have fructose malabsorption and if so are the symptoms, tests, and treatment the same as for adults?
The simple answer is yes. Studies have shown that babies and children have fructose malabsorption and there has been an increase in cases over the years. One study determined that 30% of their test group had fructose malabsorption. This is the same percentage of adults who have fructose malabsorption in Western countries. Fructose malabsorption occurs when the small intestine is unable to absorb the monosaccharide fructose. Fructose is found in sugar and honey in the form of the disaccharide sucrose composed of equal amounts of fructose and glucose. Other foods that are problematic for patients with fructose malabsorption are polyols (sugar alcohols) found in gum and some candies and fructans. Fructan is a dietary fiber found in wheat and is composed of a chain of fructose molecules.
There is a limit to how much fructose the small intestine can absorb into the bloodstream at one sitting. When that limit is reached, the fructose instead moves through to the large intestine where bacteria feed off it. This causes the production of hydrogen, carbon, and methane resulting in gas and bloating. During this time, there is also an increase of water that enters the intestine, causing diarrhea, although constipation can also be a symptom of fructose malabsorption. There are two ways that fructose is thought to be absorbed by the small intestine. The first is through a protein transporter present in the wall of the small intestine, called GLUT5. It has been shown in mice models that the number of GLUT5 present increases as the mouse ages. If this is the case in humans, then babies would absorb less fructose than children and both age groups would absorb less fructose than adults. This is a possibility because there is one study where the child no longer had fructose malabsorption after having it as a baby. The second way is that fructose is co-transported along with glucose through another protein transporter, GLUT2. For this to happen, there needs to be an equal amount or more of glucose for fructose to be absorbed.
Babies are first introduced to fructose through either formula or fruit juice. Pediatricians recommend that babies start drinking fruit juice at six months continuing as young children for the vitamin C and additional water. Orange juice, which has an equal amount of fructose and glucose used to be the most common juice given to babies but pear and apple juices have now become more common options. Unfortunately, these two juices have more fructose than glucose. Additionally, the amount of fructose children are eating has increased since the 1970s due to the rise of our consumption of soda and processed foods, which have high levels of sugar and high fructose corn syrup. One example of this increase can be seen with fruit juice. In 2013, we consumed 200 liters per person, with children 12 years and younger being the largest group of consumers at 28%. This equates to 6,763 ounces of fruit juice per person per year. With the increased amount of fructose in our diets and the potential developmental challenge of less GLUT5 in babies and children, it makes sense why fructose malabsorption is now more prevalent in babies and children.
If you are concerned that your child might have digestive issues, you should write down the behaviors and symptoms of your child after meals and snacks, then discuss the findings with your pediatrician. It is important to list out what your child ate because different digestive disorders, such as irritable bowel syndrome, Crohn’s disease, and ulcerative colitis have overlapping symptoms with fructose malabsorption. Symptoms for fructose malabsorption in babies may include screaming, gas, bloating, loose diarrhea, colic, and skin rashes. For toddlers and children, also look out for abdominal pain, cramping, irritability, nausea, and vomiting.
There are two ways that your pediatrician can test for fructose malabsorption. The first is a hydrogen breath test, which tests for the levels of hydrogen and methane produced by your large intestine after ingestion of a sugar solution. If hydrogen and/or methane are produced, your child most probably has fructose malabsorption. I discuss the hydrogen breath test in more detail in a previous post. The second way is by removing fructose from the diet, and observing if the symptoms go away. You can take it one step further, by reintroducing what you removed to find out if the symptoms return. One study indicated that the hydrogen breath test should be used on children one year and older but not with babies, because the test was not as accurate with that age group. To test if your baby has fructose malabsorption, doctors could swap out formula with fructose for one without fructose and/or eliminate fruit juice from the diet.
Fructose malabsorption does not seem to affect the growth and development of children. However, the symptoms cause pain and discomfort and may result in them missing school and events. Furthermore, if it is not treated, it can lead to additional symptoms such as joint pain, heartburn, fatigue, brain fog, headaches, depression, acne, eczema, and craving carbohydrates when they are older. Fortunately, several studies have shown that removing fructose from the diet did alleviate symptoms. To figure out the best diet for your child and to ensure their diet meets their nutritional requirements, it is important to speak with a nutritionist who can walk you through the process. What one can and cannot eat when one has fructose malabsorption is very individual because people can tolerate different amounts of fructose, fructans, and polyols and each person needs to test foods to determine what they can eat.
General guidelines for reducing symptoms in babies and children:
- Remove fructose from the diet.
- If you do eat sugar, limit the portion size.
- In general, choose sugars that have the same amount or more of glucose than fructose.
- Read the back of the box and be aware of ingredients such as fructo-oligosaccharides, inulin, and chicory root. Inulin is made from chicory root and is part of the class of fructans.
- Check medicine and vitamins that may have added fructose.
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2. Jones, H.F., et. al. (2012) Developmental changes and fructose absorption in children: effect on malabsorption testing and dietary management. Nutrition Reviews 71(5): 400-309.
3. Lebenthal-Bendor, Y., et al. (2001) Malabsorption of modified food starch (acetylated distarch phosphate) in normal infants and in 8-24-month-old toddlers with non-specific diarrhea, as influenced by sorbitol and fructose. Acta Paediatrica 90(12): 1368-1372.
4. Lozinsky, A.C., et. al. (2013) Fructose Malabsorption in Children with Functional Digestive Disorders. Pediatric Gastroenterology 50(3): 226-230.
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6. Wales, J.K.H., et. al. (1990) Isolated fructose malabsorption. Archives of Disease in Childhood. 165(2): 227–229.
7. Waibel, K.H., et. al. (2014) Fructose Intolerance/Malabsorption and Recurrent Abdominal Pain in Children. Journal of Pediatric Gastroenterology and Nutrition 58(4): 498–501
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