Is this how fructose worsens the effect of high fat diets?
05 October, 2019
New research on mice adds detail to the potential harms of combining sugar sweetened drinks with a high fat diet. Building on previous findings, that fructose promotes body fat, the latest study shows that fructose sweetened drinks can also disrupt the liver's ability to burn fat.
A recent Cell Metabolism paper describes how researchers compared the effect of adding fructose and glucose to normal and high fat diets in mice.
They found that fructose and glucose, when added to a high fat diet, affect mechanisms in the liver in opposite ways.
It appears that high levels of fructose can disrupt fat metabolism in the liver in ways that are bad for health, while high levels of glucose can improve it.
"Fructose makes the liver accumulate fat," says senior study author C. Ronald Kahn, a professor of medicine at Harvard Medical School in Boston, MA. "It acts almost like adding more fat to the diet," he continues.
"This contrasts the effect of adding more glucose to the diet, which promotes the liver's ability to burn fat, and, therefore, actually makes for a healthier metabolism," he adds.
Prof. Kahn is also head of Integrative Physiology and Metabolism at Joslin Diabetes Center, an affiliate of Harvard Medical School.
Fructose and glucose in added sugar
In their study background, the authors explain that as well as being high in fat, the typical Western diet is also high in sugar sweetened drinks.
Like increased consumption of high fat foods, higher consumption of sugar sweetened drinks has emerged as a sizeable risk factor for obesity and its complications, such as type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD).
Prof. Kahn and his team have been investigating the effects of added sugar in the diet in a series of studies, of which the recent one is the latest.
Added sugar in the diet has two forms: sucrose or high fructose corn syrup. Both these forms contain fructose and glucose.
What the team is discovering through the latest and previous findings is that these two forms of sugar have diverging effects in the liver.
In a 2017 study, for example, they showed how adding fructose to a high fat diet caused mice to develop obesity, glucose intolerance, and enlarged livers.
In contrast, adding glucose to a high fat diet did not have these effects despite the calorie intake being very similar.
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