Too much sugar is unhealthy – we know that, but it’s not just because of the high calories. Even moderate amounts of added fructose and sucrose double the body’s own fat production in the liver, researchers at the University of Zurich have shown. In the long term, this contributes to the development of diabetes or fatty liver.
Sugar is added to many common foods, and people in Switzerland consume more than 100 grams of it every day. The high calorie content of sugar causes excessive weight and obesity, as well as the diseases associated with it. But does too much sugar have other harmful effects when consumed regularly? And if so, which sugar in particular?
Even moderate amounts of sugar increase fat synthesis
Researchers at the University of Zurich (UZH) and the University Hospital Zurich (USZ) have investigated these questions. Compared to previous studies, which mainly examined the consumption of very high amounts of sugar, their results show that even moderate amounts lead to a change in the metabolism of the test participants. “80 grams of sugar a day, which corresponds to around 0.8 liters of a normal soft drink, increases fat production in the liver. And the overactive fat production continues for a longer period of time, even if no more sugar is consumed, ”says study director Philipp Gerber from the Department of Endocrinology, Diabetology and Clinical Nutrition.
94 healthy young men took part in the study. For a period of seven weeks, they consumed a drink sweetened with different types of sugar every day, while the control group did not. The drinks contained either fructose, glucose or sucrose (table sugar, a combination of fructose and glucose). The researchers then used tracers (labeled substances that can be tracked as they move through the body) to analyze the effects of sugary drinks on fat metabolism.
Double fat production from fructose and sucrose beyond food intake
Overall, the participants did not consume more calories than they did before the study, as the sugary drink increased the feeling of satiety and therefore reduced their caloric intake from other sources. Nevertheless, the researchers found that fructose has a negative effect: “The body’s own fat production in the liver was twice as high in the fructose group as in the glucose group or the control group – and this was still the case more than twelve hours later the last meal or sugar consumption, ”says Gerber. What was particularly surprising was that the sugar we consume most often, sucrose, stimulated fat synthesis a little more than the same amount of fructose. Previously, it was thought that fructose was most likely to cause such changes.
More likely to develop fatty liver or diabetes
Increased fat production in the liver is an important first step in developing common diseases such as fatty liver and type 2 diabetes. From a health point of view, the World Health Organization recommends limiting daily sugar consumption to around 50 grams or, even better, to 25 grams. “But we are a long way from this brand in Switzerland,” says Philipp Gerber. “Our results are a critical step in researching the harmful effects of added sugars and will be of great importance for future dietary recommendations.”
Reference: “Beverages sweetened with fructose and sucrose, but not with glucose promote de novo lipogenesis in the liver: A randomized controlled study” by Bettina Geidl-Flueck, Michel Hochuli, Ágota Németh, Anita Eberl, Nina Derron, Harald C . Köfeler and Luc Tappy Kaspar Berneis, Giatgen A. Spinas and Philipp A. Gerber, March 5, 2021, Journal of Hepatology.
DOI: 10.1016 / j.jhep.2021.02.027