Fructose intake is not a proven cause of weight gain  
 
An assessment of research on the role of fructose in the onset of weight gain and cardiovascular risk factors.  
 
Several years ago, on the basis of epidemiological data, scientists in the USA established a relationship between the rising number of overweight people and the increased intake of fructose through the consumption of refreshment drinks sweetened with high-fructose corn syrup (HFCS). Many studies have since analysed the effects of foods which are high in fructose on the metabolism and hormone systems. The link between fructose intake, as it occurs in a normal diet, and weight gain has, however, not yet been scientifically proven. It is even possible that fructose, at current levels of intake, actually has positive metabolic effects. 
 
Fructose occurs naturally in fruit, honey and some types of vegetable. It is also contained in sucrose (table sugar) and used in the form of syrup to sweeten foods, or as free fructose as a sugar substitute.  In the USA, high fructose corn syrup (HFCS) is used in approximately the same quantities as sucrose to sweeten refreshment drinks and other foods. In Germany, HFCS has only been used sporadically in drinks.  
Using sales figures, an average daily fructose consumption of nearly 100g per person was calculated in the USA in the year 2000. 24-hour recall showed a daily fructose intake of 54.7g per person. There is no precise data for Germany. The average level of consumption is probably approximately a third lower than in the USA, where young people are presumed to have a larger intake of fructose because of their higher consumption of refreshment drinks than older people. The consumption of diabetic foods, which also contain fructose as a sugar substitute, might play a secondary role as a source of intake.  
Some scientists see a link between an excessive intake of free fructose and the risk of developing metabolic syndrome. Indeed, increased blood levels of triglyceride could be induced in subjects, as well as an insulin resistance in liver and fat tissue. However, these were solely the results of fructose intake in extreme amounts, which means that a link to normal intake amounts is uncertain.  A daily fructose intake of up to 50g, however, displayed no significant effects on the blood level of triglyceride after a meal, and a high daily intake of 100g of fructose (which is assumed to be by far higher than the current average intake in Germany) had no influence on clinical triglyceride levels or body weight.   

A moderate fructose intake, on the other hand, probably has a positive effect: it improves glucose tolerance, increases glycogen synthesis in the liver and reduces the glycemic response to glucose stress.  A daily fructose intake of up to 90g has a positive effect on HbA1c values. A large panel of American experts has recently systematically reviewed and discussed scientific literature on the relationship between HFCS intake and weight gain, and in the process came to the following assessments:  

• The results of ecological studies, which link the consumption of HFCS to a higher body mass index (BMI) rating, are unreliable. The results of epidemiological studies and randomised control trials are inconclusive.
• No studies identifying the possible differences between HFCS intake and sugar intake and their effects currently exist.
• The ratio of fructose to glucose in American foods has remained unchanged in the last 50 years.
• According to the current state of the literature, the contribution of HFCS to weight gain is no different to that of other sources of food energy.   
 
In the light of current knowledge, it is not appropriate to develop a risk scenario based on fructose intake, even for people who eat diabetic food.  Due to the associated high intake of energy (from sucrose), only the high consumption of sugary drinks, as is increasingly common among younger age groups, poses a risk and should be limited.   
You can find further information at: www.lci-koeln.de www.suessefacts.de 
 
Source: “LCI Moderne Ernährung heute, September 2009“ (LCI modern nutrition today) by Prof. Dr. Hans Hauner, Munich