I see lots of patients complaining of stomach-ache, bloating, feeling tired, and some have bowel problems ranging from constipation to severe diarrhoea. If we look at our heritage, our food's evolution has raced ahead of our own development, and this has affected our ability to digest our food. Also, wider imports of tropical fruit and vegetables from far flung continents means we are at times eating foods outside our own culture all year round, so our fructose intake can rise exponentially.
Some diet regimens recommend eating larger volumes of fruit, leading to an increase in fructose and the above symptoms. A trend for juicing and smoothies has also affected individuals trying to lead a healthier food lifestyle but triggering a host of symptoms because of the trends requirement for increased fructose.
Vegans and vegetarians will come to me complaining of bloating, and the large quantity of fruits they are eating can be the cause. Also, some gym and lifestyle choices lead to juicing and smoothies as a quick go too food, but again this can lead to incredible discomfort.
An example of this is mango, a wonderful juicy fruit which can be used raw or cooked, and also dried. It has gradually become more and more widely used and is seen on many menus now. The problem is it is high in fructose, and some individuals have difficulty digesting this type of sugar.
We are naturally designed to better digest glucose. Our bodies do not have the dedicated means of absorption for fructose that glucose has, so this digestive difficulty means some fructose remains undigested in the large intestine, causing bacterial fermentation. This fermentation leads to the production of gas (hydrogen, CO2 and methane as well as short chain fatty acids), bloating and for some people diarrhoea. Osmotic diarrhoea can occur also due to the increased colonic sugar load.
Professor Whorwell from the University of Manchester says 'our bodies are not terribly good at digesting fructose, especially in the quantities we eat these days, with year-round access as well'.
Fructose malabsorption can go hand in hand with IBS, Crohn's disease and IBD (inflammatory Bowel Disease), and 'approximately 1/3rd of IBS sufferers will have fructose intolerance' (quoted Julie Thompson, Specialist Gastroenterology Dietician.)
Fructose connected to depression and low mood
Fructose malabsorption can also be linked too depression or low mood, as fructose has been associated with blocking the production of serotonin! It's interesting to note that children's behaviour has been affected by fructose intake. Fructose is used to sweeten many foods, and marketing and manufacture has made these very appealing and available to children, and behaviour changes have matched this increase.
Some fruit and vegetables are better tolerated than others, so random exclusion is not a good idea. Exclusion should be properly managed to prevent further mal-absorption and mal-nutrition.
Glucose has been known to counteract the effects of fructose; however it must not be used as a preventative as glucose will have an effect on the metabolism and therefore could lead to the development of other disorders.
The FODMAP regimen has become a popular route to attempt to resolve fructose malabsorption symptoms. This diet must be managed by a health professional and should only be followed for a period of up to 8 weeks. It involves limited eating, through the exclusion of foods high in fructose, so long-term use could lead to malnutrition.
Here is a small sample of foods which are high in Fructose:
Tinned Cranberries but not fresh
Certain sweeteners can increase or decrease fructose intolerance and where these are often added to many foods, it is worth double-checking packages.
Not known to have an effect:
Sorbitol – Fructose intolerance increases
Glucose – Fructose intolerance decreases.
Dextrose – Fructose intolerance decreases
Credit to the Clairmont Digestive Clinic for the information below. This is a fantastic quick guide.