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Coffee consumption and plasma total homocysteine: The Hordaland Homocysteine Study
O Nygård1, H Refsum, P M Ueland
1Department of Clinical Biology, University of Bergen, Norway. ottar.nygard@smis.uib.no
Insights
Coffee consumption is linked to higher total homocysteine (tHcy) levels, a risk factor for cardiovascular disease. This association persists even after accounting for smoking and diet, suggesting a direct effect of coffee on tHcy.
Area of Science:
- Cardiovascular epidemiology
- Nutritional science
- Clinical biochemistry
Background:
- The health effects of coffee consumption are debated.
- Elevated plasma total homocysteine (tHcy) is a known risk factor for cardiovascular disease and adverse pregnancy outcomes.
Purpose of the Study:
- To investigate the association between coffee consumption and plasma tHcy concentrations.
- To explore potential confounding factors in the coffee-tHcy relationship.
Main Methods:
- Cross-sectional study of 7589 men and 8585 women aged 40-67 in western Norway.
- Data collected on coffee consumption, smoking, diet, and plasma tHcy levels.
- Statistical analysis to determine dose-response relationships and adjust for confounders.
Main Results:
- A significant positive dose-response relationship was observed between coffee intake and plasma tHcy.
- Heavy coffee drinkers (> or = 9 cups/day) had higher tHcy levels compared to non-users.
- The association remained significant after adjusting for smoking, vitamin supplements, and fruit/vegetable intake.
- Combined high coffee intake and smoking showed particularly elevated tHcy levels.
Conclusions:
- Coffee consumption is independently associated with increased plasma tHcy concentrations.
- tHcy may be a mediator of potential adverse health effects associated with heavy coffee consumption.
- Further research is warranted to elucidate the mechanisms underlying the coffee-tHcy link.
Abstract:
The health consequences of coffee drinking remain controversial. We report on an association between coffee consumption and the concentration of total homocysteine (tHcy) in plasma, a risk factor for cardiovascular disease and for adverse pregnancy outcome. The study population consisted of 7589 men and 8585 women 40-67 y of age and with no history of hypertension, diabetes, ischemic heart disease, or cerebrovascular disease. They were recruited from Hordaland county of western Norway in 1992-1993. Daily use of coffee was reported by 89.1% of the participants, of whom 94.9% used caffeinated filtered coffee. There was a marked positive dose-response relation between coffee consumption and plasma tHcy, which was stronger than the relation between coffee and total serum cholesterol. In 40-42-y-old men, mean tHcy was 10.1 mumol/L for nonusers and 12.0 mumol/L for drinkers of > or = 9 cups of coffee/d. Corresponding tHcy concentrations in 40-42-y-old women were 8.2 and 10.5 mumol/L, respectively. Although coffee drinking was associated with smoking and lower intake of vitamin supplements and fruit and vegetables, the coffee-tHcy association was only moderately reduced after these variables were adjusted for. The combination of cigarette smoking and high coffee intake was associated with particularly high tHcy concentrations. A strong inverse relation between tea and tHcy concentration in univariate analysis was substantially attenuated after smoking and coffee drinking were adjusted for. The results of the present report should promote future studies on tHcy as a possible mediator of adverse clinical effects related to heavy coffee consumption.