Moderate coffee consumption increases plasma glutathione but not homocysteine in healthy subjects


Professor V. Fogliano, Dipartimento di Scienza degli Alimenti, Università di Napoli ‘Federico II’, Parco Gussone, 80055, Portici, Napoli, Italy.


Background : The consumption of unfiltered coffee, containing bioactive diterpenes, causes an increase in plasma homocysteine concentration. A slight increase in plasma homocysteine is also caused by large quantities of filtered coffee. Coffee terpenes also raise plasma glutathione in mice.

Aim : To verify the effect of Italian-style coffee consumption on the plasma concentration of glutathione and homocysteine in healthy subjects.

Methods : Twenty-two volunteers consumed five cups of coffee per day for 1 week and maintained their usual diet. Five subjects were enrolled as controls. The intervention trial was preceded and followed by seven coffee-free days.

Results : Plasma glutathione increased by 16% (P < 0.05) on coffee consumption, and returned to the original concentration after the washout period. The increase in plasma homocysteine concentration (13% after 1 week of coffee intake) was not significant. No differences in glutathione or homocysteine concentration were observed in the control group. No variation of plasma hydroperoxide concentration was detectable.

Conclusions : A coffee intake regimen, representing the average consumption of coffee drinkers in Italy, increased the plasma concentration of glutathione, but no significant increase in the plasma homocysteine concentration was detected.