Caffeine metabolites lower risk of hypertension in adults

Final caffeine metabolites, but not caffeine per se, significantly correlate with a reduced risk of hypertension in adults, reports a US study.

A total of 2,278 individuals aged 18–80 years were included using data from 2009–2010 National Health and Nutrition Examination Survey. The investigators measured urinary methyluric acids (MU) and methylxanthines (MX) products of caffeine metabolism using high-performance liquid chromatography-electrospray ionization-tandem quadrupole mass spectrometry.

Multivariate logistic regression was used to model hypertension (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg) as functions of urinary coffee metabolites.

Hypertension risk significantly decreased across quartiles of 3-MU, 7-MU, 3-MX and 7-MX, with 7-MU being the more powerful metabolite. Adults in the upper quartile of 7-MU had an 81-percent (95 percent confidence interval [CI], –90 to –22 percent) lower risk of hypertension compared with those in the bottom quartile.

On the other hand, the odds ratio for hypertension from the bottom to the upper quartile were 4.47 (95 percent CI, 1.21–16.50) for 1,3-dimethyluric acid, 4.45 (95 percent CI, 1.48–13.39) for 1,3-dimethylxanthine, and 5.08 (95 percent CI, 1.11–23.36) for 1,7-dimethylxanthine.

Neither insulin resistance nor abdominal obesity moderated these associations.

“Most studies assessing the association between coffee consumption and hypertension ascertained caffeine intake in terms of number of cups per days and yield[ed] mixed results,” the investigators noted. “Although the inter-individual variability in the caffeine metabolism is known, the relation of caffeine metabolites with hypertension remains unsettled.”