- The consumption of moderate amounts of specific types of sugar can double the production of fat in the liver.
- This, in turn, can lead to the development of fatty liver disease and type 2 diabetes.
- A recent study found that sucrose increases fat synthesis slightly more than the same amount of fructose.
New research provides further evidence of the dangers of consuming sugar, proposing that ingesting moderate amounts of the substance can lead to a change in a person’s metabolism.
Researchers from the Medical University of Graz, Austria, and from the University of Zurich and the University Hospital of Zurich, Switzerland, recently reported their findings in theJournal of Hepatology.
Some sugars are natural components of fruits and vegetables. However, many of the processed foods we eat contain added sugars – sugar that manufacturers add to foods and beverages to enhance their taste or improve the appearance and texture of food.
High sugar intake has been linked to several health problems, including type 2 diabetes, obesity, cardiovascular disease and cancer.
In 2015, the World Health Organization (WHO) advised people to eat a maximum of 5% of their daily calories with added sugar. For a 2,000-calorie-a-day diet, that would be equivalent to 100 calories or 6 teaspoons or about 25 grams (g) of added sugar.
In 2015, market research firm Euromonitor reported that an average person in the United States consumes more than 126 g of sugar per day.
Meanwhile, the average person in the UK consumed 93.2 g.
Switzerland is not on the list of the top 10 countries whose citizens consume the most sugar. Even so, the average person there consumed 76.1 g per day in 2015.
The study authors were interested in finding out what happens when people consume moderate amounts of added sugar.
For their work, carried out between 2013 and 2016, they recruited 94 healthy male volunteers. Participants were aged 18-30 years and had a body mass index below 24kg / mtwo, which is considered a moderate weight.
The researchers selected participants with a certain weight to decrease the chances of recruiting people who possibly had already developed an increase in the fat content of the liver.
Men who already consumed sugar-sweetened drinks daily or who practiced more than 3 hours of physical activity per week were also excluded.
The researchers explained that they did not study women, “since there is evidence of divergent metabolic effects of fructose in men and women”.
In fact, a 2008 study reported that fructose caused “markedly blunt” metabolic effects in female participants compared to male participants.
The researchers initially caused participants to abstain from sugar-sweetened drinks for 4 weeks. Participants then started drinking sugar-sweetened drinks containing fructose, sucrose or glucose three times a day. A total of 80 g of each type of sugar was consumed daily.
A fourth group of participants was asked to continue abstinence from sugar-sweetened drinks.
To examine how sugar-added beverages affected individuals, the researchers used trackers, which are substances that can be followed while moving around the body.
Overall, the researchers found that the participants did not consume more calories than before the study. The authors raise the hypothesis that taking sugary drinks increased the participants’ satiety, causing them to consume fewer calories from other sources.
The researchers also reported that while participants consumed the same number of calories, adding sugar-sweetened drinks to their diets affected their overall health.
Participants who drank fructose-sweetened beverages had twice as much fat production as those who drank glucose-sweetened beverages and those who abstained from sugar-sweetened beverages.
“This still happened more than 12 hours after the last meal or consumption of sugar,” said study leader Dr. Philipp Gerber, from the Department of Endocrinology, Diabetology and Clinical Nutrition at the University of Zurich.
The accumulation of fat in the liver causes serious health problems, such as type 2 diabetes and non-alcoholic fatty liver disease.
A particularly surprising finding by the researchers was that sucrose, or table sugar – the form of sugar that humans most commonly consume – increased fat synthesis slightly more than the same amount of fructose. Until now, most scientists believed that fructose was more likely to cause these changes.
Dr. Gerber notes that the typical Swiss does not follow the WHO’s advice to limit his daily sugar consumption to 25 g. “Our results are a critical step in researching the harmful effects of added sugars and will be very significant for future dietary recommendations,” he says.
Scientists also note some limitations in their research.
They say that they had “little control” over the participants’ adherence to the study and that they did not know their “intestinal capacity”. In other words, not knowing the participants’ individual tolerability to fructose may have led to variations in the results.