Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: A randomized trial

Departments of Gastroenterology and Hepatology, Internal Medicine, Pediatrics, and Clinical Chemistry, University Hospital Nijmegen, Netherlands.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 03/2000; 71(2):480-4.
Source: PubMed


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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    • "We also explored the relationship between tea-derived polyphenol O-methylation and tHcy response to tea and observed no linear relationship. Tea and coffee, and their major constituents, polyphenols and caffeine, can raise tHcy (Grubben et al. 2000; Urgert et al. 2000; Olthof et al. 2001; Verhoef et al. 2002). "
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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 · 3.45 Impact Factor
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    • "The positive association reported between coffee consumption and tHcy concentration is consistent with several observational (Nygard et al, 1997; Stolzenberg-Solomon et al, 1999; De Bree et al, 2001a; Jacques et al, 2001) and intervention studies (Grubben et al, 2000; Urgert et al, 2000; Christensen et al, 2001). Caffeine has been proposed as the causative agent as it might act as a B6 antagonist inhibiting the conversion of homocysteine to cysteine (Grubben et al, 2000; Verhoef et al, 2002). Chlorogenic acid, a polyphenol, also present in coffee may also be partly responsible for the increase in tHcy (Olthof et al, 2001). "
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    ABSTRACT: To examine the associations between various lifestyle factors--smoking habits, physical activity, dietary habits, coffee, tea, and alcohol consumption--and homocysteine (tHcy) in relation to MTHFR(C677T) genotype. Cross-sectional population-based study. Residents of Copenhagen County, Denmark. A random sample of 6457 men and women aged 30-60 years drawn from the Civil Registration System and invited to a health examination in 1999-2001. A total of 2788 participants were included in the statistical analysis. tHcy was measured using a Fluorescent Polarization Immuno Assay. MTHFR-genotype was determined by PCR and RFLP analysis. Information about lifestyle factors was obtained from a self-administered questionnaire. Daily smoking, less healthy dietary habits, and coffee drinking were associated with elevated tHcy concentrations independent of other determinants. Wine consumption was related to tHcy in a J-shaped manner, whereas beer consumption was negatively associated with tHcy after multiple adjustments. Interaction was observed between smoking status and MTHFR-genotype, smoking status and sex, and beer consumption and age. The effect of smoking was more pronounced in persons with the TT genotype and in women. The effect of beer consumption was more pronounced at younger than at older ages. Smoking status, dietary habits, coffee intake, wine, and beer consumption were major lifestyle determinants of tHcy. Changes in these lifestyle factors may reduce tHcy concentrations, thereby lowering cardiovascular risk in the general population. Danish Medical Research Council, Danish Centre for Evaluation and Health Technology Assessment, and Danish Heart Foundation.
    European Journal of Clinical Nutrition 09/2004; 58(8):1142-50. DOI:10.1038/sj.ejcn.1601942 · 2.71 Impact Factor
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    • "Diterpenes are, as mentioned above, unlikely candidates as the effects on tHcy levels are seen both with filtered and unfiltered coffee, which differ considerably with regard to the content of diterpenes (Bak, 1990). At present, caffeine seems a more likely candidate (Nygard et al, 1997; Grubben et al, 2000; de Bree et al, 2001). This is also suggested by the findings in the Hordaland Homocysteine study (Nygard et al, 1997) and the study of Jacques et al (2001), where the use of decaffeinated coffee not was shown to be related to the tHcy concentration . "
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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 · 2.71 Impact Factor
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