Fructose: friend or foe?
The German Nutrition Society (DGE) recommends that you should eat two portions of fruit and three portions of vegetables a day. But is it harmful to eat more fruit? After all, we read all kinds of negative things about the "natural sweetness" of fructose. Not much is left of the once good reputation of fructose. Find out why this is and what you should look out for in your diet in today's blog post.Glucose (dextrose) and fructose (fruit sugar) are so-called single sugars (monosaccharides). Both can be contained in food in free form as simple sugars or bound as two or multiple sugars (e.g. household sugar, starch). During digestion, the bound monosaccharides are released, absorbed via the intestine and then metabolised in the body. Glucose is used by our body cells to generate energy, while fructose is mainly stored in the form of fat - especially in the liver or abdomen. The problem with this is that high amounts of fructose can favour the development of a so-called fatty liver, which in the worst case can lead to liver cirrhosis. Studies also show that a high consumption of fructose favours obesity, gout, diabetes and cardiovascular diseases (e.g. heart attack, stroke). Fructose is also said to have a negative effect on the feeling of satiety. In contrast to glucose, fructose does not lead to a rise in blood sugar and the associated release of the hormone insulin, which has a satiating effect. Fructose therefore makes you hungry again more quickly.
Fructose: industry vs. nature
With these study results, it is no wonder that the "natural sweetness from fruit" is now considered an unhealthy fattening agent. Unfortunately, there are currently no figures on how much fructose our body can metabolise per day and what maximum amount should not be exceeded. The WHO generally recommends no more than 25 g of sugar per day. However, the sugar naturally contained in food is excluded from this. Fruit lovers can therefore breathe a sigh of relief: to date, there are no known harmful effects of high fruit consumption (provided you do not exceed the total calorie requirement and do not have a fructose intolerance). However, if you want or need to save calories, you should favour vegetables.Much more dangerous and the real problem is the fructose content of processed foods and drinks. Yoghurt, cola, soft drinks, ready meals, sweets, etc.: Under the name high-fructose corn syrup (HFCS), corn syrup, fructose-glucose syrup or isoglucose, the food industry uses fructose as a sweetener, and not in short supply. This is because fructose is not only twice as sweet as glucose, it is also cheaper and easier to produce.
In Germany, the use of fructose in food was still restricted by the EU sugar quota until October 2017. The abolition of this regulation has paved the way for the cheap sweetener to find its way onto domestic supermarket shelves. So we will certainly be reading more about the dangers of high fructose consumption in the future. However, one thing should not be forgotten: Household sugar (sucrose) also consists of glucose and fructose and has a similar fructose content to fructose-glucose syrup. It is best to avoid any type of added sugar and favour natural, unprocessed foods instead.
Fructose in fruit and vegetables is not harmful to our bodies. On the contrary, because together with the fructose, fibre, micronutrients and phytochemicals are also absorbed. However, industrially produced fructose, which is found in many processed foods, should be avoided. The same applies to other isolated sugars (e.g. sucrose).
- Stanhope KL. Sugar consumption, metabolic disease and obesity: The state of the controversy. Crit Rev Clin Lab Sci. 2016;53(1):52-67.