Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: a randomized trial.
ABSTRACT An elevated plasma homocysteine concentration is a putative risk factor for cardiovascular disease. Observational studies have reported an association between coffee consumption and plasma homocysteine concentrations.
We studied the effect of coffee consumption on plasma homocysteine in a crossover trial. We used unfiltered coffee so as to include the possible effects of coffee diterpenes, which are removed by filtering.
Sixty-four healthy volunteers (31 men and 33 women) with a mean (+/-SD) age of 43 +/- 11 y were randomly assigned to 2 groups. One group (n = 30) drank 1 L unfiltered cafetière (French press) coffee daily for 2 wk. Such coffee is rich in the cholesterol-raising diterpenes kahweol and cafestol. The other group (n = 34) received water, milk, broth, tea, and chocolate drinks instead of coffee. After a washout period of 8 wk, both groups received the alternate intervention for another 2 wk.
Consumption of 1 L unfiltered coffee/d for 2 wk significantly raised fasting plasma homocysteine concentrations by 10%, from 12.8 to 14.0 micromol/L.
Unfiltered coffee increases plasma homocysteine concentrations in volunteers with normal initial concentrations. It is unclear whether the effect is caused by the cholesterol-raising diterpenes present exclusively in unfiltered coffee or by factors that are also present in filtered coffee.
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ABSTRACT: Plasma total homocysteine concentrations (tHcy) are a putative risk factor for CVD. Tea is a rich dietary source of polyphenols and caffeine, both of which may raise tHcy. However, it is possible that much of any effect is transitory and may be influenced by the consumption of food. Our objective was to investigate the acute effect of tea, at a dose representative of ordinary population intakes, on tHcy and to determine whether consumption of a meal influences the magnitude of any effect. Measurements of tHcy were performed in twenty participants at baseline and 3.5 h after drinking three cups of black tea or hot water (consumed at time 0, 1.5 and 3 h) with and without a meal: a total of four treatments administered in random order. Drinking tea resulted in an acute increase in tHcy (0-30 (95 % CI 0.04, 0.56) micromol/l, P=0.022). The meal resulted in an acute decrease in tHcy (-0.42 (95 % CI -0.68, -0.16) micromol/l, P=0.002). There was no interaction between tea and meal on tHcy (P=0.40); that is, the effect of tea on tHcy was not different in the fasting and non-fasting state. Our results suggest that drinking black tea can cause a small acute increase in tHcy and that this effect is not enhanced in the non-fasting state. Given that results of population studies have generally shown a negative association between tea intake and tHcy, the significance of these findings to CVD risk remains uncertain.British Journal Of Nutrition 06/2007; 97(5):842-6. DOI:10.1017/S0007114507669190 · 3.34 Impact Factor
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ABSTRACT: Elevated levels of plasma total homocysteine (tHcy) are identified as independent risk factors for coronary heart disease and for fetal neural tube defects. tHcy levels are negatively associated with folic acid, pyridoxine and cobalamine, and positively associated with coffee consumption and smoking. A total of 600 ml of filtered coffee results in a tHcy increase that 200 mug of folic acid or 40 mg of pyridoxine supplementation might eliminate. Randomised, blinded study with two consecutive trial periods. Free living population. Volunteers. A total of 121 healthy, nonsmoking men and women (78%) aged 29-65 y. (1) A coffee-free period of 3 weeks, (2) 600 ml coffee/day and a supplement of 200 mug folic acid/day or placebo for 4 weeks, (3) 3-week coffee-free period, (4) 600 ml coffee/day and 40 mg pyridoxine/day or placebo for 4 weeks. The difference between the change in tHcy in the supplement group and the change in tHcy in the placebo group during the 4-week trial period. Coffee abstention resulted in a tHcy decrease of 1.04 mumol/l for the whole group. In the subsequent coffee period, a further decrease of 0.17 mumol/l was observed in the folic acid group whereas an increase of 1.26 mumol/l was observed in the placebo group, the difference was 1.43 mumol/l (95% CI: 0.80, 2.07). Pyridoxine supplement had no impact on tHcy levels. Supplementation of 200 mug folic acid/day eliminates the tHcy increasing effect of 600 ml filtered coffee in subjects not already on folic acid supplements. A supplement of 40 mg pyridoxine/day does not have the same effect.European Journal of Clinical Nutrition 11/2003; 57(11):1411-7. DOI:10.1038/sj.ejcn.1601703 · 2.95 Impact Factor
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ABSTRACT: Earlier studies and trials have shown a serum cholesterol raising effect of unfiltered coffee, which is reduced by about 80% in filtered coffee. Recent cross-sectional studies and trials, however, have indicated that filtered coffee may have a more pronounced serum cholesterol raising effect than previously anticipated. The objective of this controlled study was to assess the effects of the intake and abstention of filtered brewed coffee on blood lipids. A prospective, controlled study with four consecutive trial periods. The first and third periods were 3 weeks of total coffee abstention. The second and fourth periods consisted of 4 weeks with the subjects consuming 600 ml filter brewed coffee/day. Free-living population. Volunteers. A total of 121 healthy, nonsmoking men and women aged 29-65 y. Not applicable. Serum total cholesterol, serum HDL cholesterol, serum triglycerides, serum lipoprotein (a) (Lp(a)), blood pressure and heart rate. The two coffee abstention periods were associated with a decline in serum cholesterol of 0.22 mmol/l (95% CI -0.31, -0.13) and 0.36 mmol/l (95% CI -0.46, -0.26), respectively. Filtered coffee/day 600 ml increased serum cholesterol by 0.25 mmol/l (95% CI 0.15, 0.36) and 0.15 mmol/l (95% CI 0.04, 0.26) during the two coffee drinking periods. Coffee abstention for 3 weeks decreased total serum cholesterol by 0.22-0.36 mmol/l. A volume of 600 ml (about four cups) of filtered coffee/day during 4 weeks raised total serum cholesterol by 0.15-0.25 mmol/l.European Journal of Clinical Nutrition 10/2003; 57(9):1164-8. DOI:10.1038/sj.ejcn.1601668 · 2.95 Impact Factor