The effect of brewed and instant coffee on reproduction and teratogenesis in the rat

Abstract

A blend of roasted and ground coffees was brewed and an instant coffee was prepared daily and given to rats in place of their drinking water, at either full-strength (100%) or as 50 or 25% dilutions. A control group was given water. The administration of the coffee solutions began shortly after weaning and continued for about 30 weeks, through two pregnancies. During pregnancy and lactation the caffeine intakes were approximately 80, 40, or 20 mg/kg/day, being slightly higher in the groups given brewed coffee and slightly lower in the groups give instant coffee. The parent rats given either brewed or instant coffee grew as well as or better than controls and ate more feed, although feed efficiencies were not different. The rats given full-strength coffees drank significantly less than controls, but the ones given 50 or 25% solutions drank more. Both male and female rats given 100% brewed or instant coffee to replace their drinking water had enlarged kidneys at 13 and 30 weeks, while only the females given 50% solutions of either coffee had enlarged kidneys. The females given full-strength coffees had enlarged livers at both times, while the females given 50% brewed coffee had enlarged livers only at 30 weeks. No effects on the organ weights were seen in the groups given 25% coffee solutions. No effects were seen on reproduction or lactation, except that the pups in the groups given 100% brewed or instant coffee to replace their drinking water weighed significantly less than the controls at weaning. Neither embryotoxicity nor frank teratogenicity was seen as a result of coffee ingestion. However, the fetuses in the groups given 100 or 50% solutions of the brewed coffee and 100% instant coffee in place of drinking water had a significantly higher incidence of unossified sternebrae, indicating a delay in calcification.