Coffee and caffeine attenuate symptoms of metabolic syndrome in diet-induced obese rats

Aim: Coffee, a rich source of caffeine, chlorogenic acid and diterpenoid alcohols, has been part of the human diet since the 15th century. Pharmacological actions of caffeine include antagonism of adenosine receptors and inhibition of phosphodiesterase activity. A1 adenosine receptors present on adipocytes are involved in control of fatty acid uptake and lipolysis.

Method: This study characterised the effects of Colombian coffee extract and caffeine in a rat model of diet-induced metabolic syndrome. 8—9-Week-old male Wistar rats were divided into two sets of four groups. For each intervention, two groups of rats were fed a corn starch-rich diet whereas the other two groups were given a high-carbohydrate, high-fat diet with 25% fructose in drinking water for 16 weeks. One group fed each diet was supplemented with 5% aqueous coffee extract or 0.5 g caffeine/kg food for the final 8 week of this protocol.

Results: The high-carbohydrate, high-fat diet-fed rats showed the symptoms of metabolic syndrome leading to cardiovascular remodelling and non-alcoholic fatty liver disease. Both coffee extract and caffeine supplementations in high-carbohydrate, high-fat diet-fed rats attenuated impairment in glucose tolerance, hypertension, cardiovascular remodelling and non-alcoholic fatty liver disease. Coffee extract increased body weight without changing dyslipidaemia whereas caffeine reduced body weight and body fat with increases in plasma lipid concentrations.

Conclusion: Coffee extract did not change abdominal fat deposition, so the complex mixture in coffee negates the lipolytic effects of caffeine in adipocytes, likely due to caffeine antagonism of A1 adenosine receptors.