Some scientists suspect that sugar not only makes you fat, but is also directly responsible for type 2 diabetes, heart attacks and joint problems. Fruit sugar, also known as fructose, in particular is suspected of causing illness.
Ordinary table sugar, also known as sucrose, consists of one molecule of glucose and one molecule of fructose bound together. All organs in the body can use glucose. Fructose, on the other hand, can practically only be processed by the liver. The fructose content from the food ends up there concentrated. The liver converts most of it directly into fat. And that has a whole range of negative effects.
Research in animals and humans shows that fructose leads to fatty liver, high blood lipid levels, high blood pressure and insulin resistance. When these symptoms appear, the balance between insulin, sugar and fat production is disrupted. These signs are summarized under the term “metabolic syndrome”. It is considered a precursor to type 2 diabetes and is an important risk factor for arterial heart disease.
The American pediatrician Robert Lustig has therefore put forward the thesis that we are not dealing with an obesity epidemic, but with an epidemic of the metabolic syndrome – triggered by sugar consumption. The metabolic syndrome then leads to obesity, diabetes and heart disease. He goes so far as to call fructose a “metabolic toxin,” comparable to alcohol, which is also toxic regardless of its caloric content. In addition, fructose probably messes up appetite regulation and therefore does not fill you up. It does not trigger insulin release, does not lower ghrelin levels and can lead to leptin resistance. All three substances regulate our feelings of hunger and satiety.
There is now a robust body of studies that demonstrate the described effects of fructose, and in part also for glucose. The dose, however, is controversial. “That probably only plays a role from 30 to 40 grams of fructose a day,” says Andreas Pfeiffer from the German Institute for Human Nutrition in Potsdam. The Longer Better Living Institute at the University of Bremen, on the other hand, advises not to consume more than 15 to 20 grams of fructose per day.
Don’t worry: Fruit contains comparatively small amounts of fructose and can therefore be eaten in large quantities without hesitation; Nobody has ever gotten fat from eating apples, strawberries, apricots or plums. However, this type of sugar, which sounds so natural, is added to many soft drinks, desserts and other processed foods – and these are often advertised as “sweetened only with fructose”. So it’s no wonder that in 2010 the then President of the Federal Chamber of Pharmacists described fructose as a “wolf in sheep’s clothing”.