Kinetics of homocysteine metabolism after moderate alcohol consumption

Background: Moderate alcohol consumption is associated with a decreased risk of cardiovascular disease. Because plasma homocysteine (tHcy) is considered an independent risk factor for cardiovascular disease and associated with alcohol consumption, the authors investigated the effect of moderate alcohol consumption on kinetics of plasma tHcy concentration, vitamin B status, and other parameters involved in tHcy metabolism. Methods: Ten healthy men and nine healthy postmenopausal women (aged 45-65 years) participated in a randomized, diet-controlled, crossover trial. They consumed beer or alcohol-free beer (men: 4 units/day; women: 3 units/day) during 3 weeks, separated by a 1-week washout. On days 5, 10, 15, and 20 of each period, fasting blood samples were taken. Results: Plasma tHcy (μM) and S-adenosyl methionine/S-adenosyl homocysteine ratio were not affected by consumption of beer or alcohol-free beer (p = 0.33 and p = 0.14, respectively). Plasma pyridoxal-5-phosphate (μg/liter) increased during consumption of beer (+11.0%), whereas it decreased during consumption of alcohol-free beer (-34.0%; p = 0.042). Changes over time of plasma vitamin B₆ (μg/liter) were similar to changes in plasma pyridoxal-5-phosphate (p = 0.10). Serum vitamin B₁₂ was higher (p < 0.001) after 3 weeks consumption of alcohol-free beer (382.8 ± 23.7 pg/liter) as compared with beer consumption (327.5 ± 22.2 pg/liter). Changes in serum methionine, cysteine, cystathionine, and plasma folate were not different between beer-drinking and alcohol-free beer-drinking periods. Conclusions: This study shows that moderate alcohol consumption does not affect plasma tHcy concentrations or S-adenosyl methionine/S-adenosyl homocysteine ratio. However, it does increase plasma vitamin B₆ and decrease serum vitamin B₁₂.