A recent study has shown that fibroblast growth factor 21 (FGF21), a liver-generated hormone, suppresses the FGF21 is produced in response to high carbohydrate levels, in which it enters the bloodstream and signals the brain to suppress the preference for sweets. Matthew Potthoff, assistant professor of pharmacology in the University of Iowa Carver College of Medicine, noted that this is the “first liver-derived hormone that regulates sugar intake specifically.”consumption of simple sugars.
Earlier studies have shown how some hormones affect appetite. However, these do not regulate any specific macronutrient (eg, carbohydrate, protein, fat) and are produced in organs other than the liver. FGF21 has been known to boost insulin sensitivity but the new findings “can help people who might not be able to sense when they’ve had enough sugar, which may contribute to diabetes,” said Lucas BonDurant, a doctoral student and co-first author in the study.
Researchers used genetically-engineered mouse models and pharmacological approaches to study FGF21 in regulating sugar cravings. Normal mice were injected with FGF21 and were given a choice between a normal diet and a sugar-enriched diet. These mice did not completely stop eating sugar but consumed 7 times less than normal. The team also looked at mice that either did not produce FGF21 at all or overproduced FGF21 (>500 times more than normal mice). When presented with the same two diets as the normal mice, researchers saw that the mice that didn’t produce FGF21 all consumed more sugar whereas the mice that overproduced FGF21 consumed less sugar.
Study findings support the conclusion that FGF21 decreased appetite and sugar intake. It did not, however, decrease intake of all sugars (eg, sucrose, fructose, glucose) nor did it affect the intake of complex carboydrates. The new data may help patients who are obese or have diabetes, researchers noted. More studies are needed to see if other hormones exist to regulate appetite for specific macronutrients comparable to the effects of FGF21 on carbohydrate intake.