Heavy coffee consumption and plasma homocysteine: a randomized controlled trial in healthy volunteers

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Abstract
Background: An elevated plasma concentration of total homocysteine is considered to be a strong risk factor for cardiovascular disease. Heavy coffee drinking has been related to high homocysteine concentrations in epidemiologic studies and in one experiment in which healthy subjects drank unfiltered, boiled coffee. Objective: Our goal was to determine whether daily consumption of paper-filtered coffee raises plasma concentrations of total homocysteine in healthy subjects. Design: Twenty-six volunteers (18–53 y of age) consumed 1 L/d of paper-filtered coffee brewed with 70 g regular ground beans or no coffee for 4 wk each in a randomized, crossover design. Results: The mean (±SD) plasma concentration of total homocysteine in fasting blood was 8.1 ± 1.8 μmol/L after abstention from coffee and 9.6 ± 2.9 μmol/L after 3–4 wk of coffee drinking, a difference of 1.5 μmol/L (95% CI: 0.9, 2.1 μmol/L) or 18% (P < 0.001). Coffee increased homocysteine concentrations in 24 of 26 individuals. Circulating concentrations of vitamin B-6, vitamin B-12, and folate were unaffected. Conclusion: Drinking large quantities of paper-filtered coffee raises fasting plasma concentrations of total homocysteine in healthy individuals.