Your liver may control your sweet tooth and alcohol cravings, says new study

Can your liver control your sweet tooth and alcohol cravings?

Your may imagine your liver cursing at you this holiday season, but it could actually be responsible for helping you pass on that fourth glass of wine or second piece of cake.

Researchers from UT Southwestern in Dallas, in collaboration with Pfizer today published a paper in the journal Cell Metabolism called “FGF21 Mediates Endocrine Control of Simple Sugar Intake and Sweet Taste Preference by the Liver“. The study found a hormone called Fibroblast growth factor 21 (FGF21) to be associated with macronutrient preference, including carbohydrate, fat, and protein intake.

“A lot of work has examined the central mechanisms regulating sugar-seeking behavior, but the post-ingestive mechanisms regulating sugar appetite are poorly understood,” says Matthew Potthoff of the University of Iowa, who worked on the study.

Until about 20 years ago, obesity from overeating was regarded as a mere behavioral disorder. But a study from Douglas Coleman of the Jackson Laboratory in Maine and Jeffrey Friedman at Rockefeller University found that hormones regulate appetite, and that an imbalance could lead to weight gain.

As for sugar in particular, one expert says we are hard-wired to crave it because apes survived on sugar-rich fruit.

“Sugar is a deep, deep ancient craving,” says Daniel Lieberman, an evolutionary biologist at Harvard University, who is the author of “The Story the Human Body: Evolution, Health, and Disease. “For millions of years, our cravings and digestive systems were exquisitely balanced because sugar was rare. Apart from honey, most of the foods our hunter-gatherer ancestors ate were no sweeter than a carrot. The invention of farming made starchy foods more abundant, but it wasn’t until very recently that technology made pure sugar bountiful.”

The researchers on the UT Southwestern study administered recombinant FGF21 to one group of mice and 1% sunflower oil to another. They found a decreased sweet preference in those that took the FGF21. They then performed the same test on monkeys and arrived at the same result. The second part of the study involved exposing mice to increasing concentrations of ethanol in a two-bottle preference and found that FGF21 suppressed ethanol preference.

One of the researchers on the study said the findings were a real revelation.

“We never imagined that a circulating, liver-derived factor would exist whose function is to control sweet appetite, says his co-senior author Matthew Gillum of the University of Copenhagen. “We are very excited about investigating this hormonal pathway further.”

So are we headed toward a future in which a simple pill could end the craving for booze and sweets? Potthoff says more work is needed to fully realize the implications of their findings.

“In addition to identifying these neural pathways, we would like to see if additional hormones exist to regulate appetite for specific macronutrients like fat and protein, comparable to the effects of FGF21 on carbohydrate intake,” Potthoff says. “If so, how do those signals intertwine to regulate the neural sensing of different macronutrients?”

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