Consumption of high doses of chlorogenic acid, present in coffee, or of black tea increases plasma total homocysteine concentrations in humans.
BACKGROUND
In population studies, high intakes of coffee are associated with raised concentrations of plasma homocysteine, a predictor of risk of cardiovascular disease. Chlorogenic acid is a major polyphenol in coffee; coffee drinkers consume up to 1 g chlorogenic acid/d.


OBJECTIVE
We studied whether chlorogenic acid affects plasma total homocysteine concentrations in humans. For comparison we also studied the effects of black tea rich in polyphenols and of quercetin-3-rutinoside, a major flavonol in tea and apples.


METHODS
In this crossover study, 20 healthy men and women ingested 2 g (5.5 mmol) chlorogenic acid, 4 g black tea solids containing approximately 4.3 mmol polyphenols and comparable to approximately 2 L strong black tea, 440 mg (0.7 mmol) quercetin-3-rutinoside, or a placebo daily. Each subject received each of the 4 treatments for 7 d, in random order.


RESULTS
Total homocysteine in plasma collected 4-5 h after supplement intake was 12% (1.2 micromol/L; 95% CI: 0.6, 1.7) higher after chlorogenic acid and 11% (1.1 micromol/L; 95% CI: 0.6, 1.5) higher after black tea than after placebo. Total homocysteine in fasting plasma collected 20 h after supplement intake was 4% (0.4 micromol/L; 95% CI: 0.0, 0.8) higher after chlorogenic acid and 5% (0.5 micromol/L; 95% CI: 0.0, 0.9) higher after black tea than after placebo. Quercetin-3-rutinoside did not significantly affect homocysteine concentrations.


CONCLUSIONS
Chlorogenic acid, a compound in coffee, and black tea raise total homocysteine concentrations in plasma. Chlorogenic acid could be partly responsible for the higher homocysteine concentrations observed in coffee drinkers. Whether these effects on homocysteine influence cardiovascular disease risk remains to be established.
Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen, Netherlands. margreet.olthof@staff.nutepi.wau.nl
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Olthof
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Hollman
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Zock
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Katan
D000328:Adult; D002318:Cardiovascular Diseases / Q000209:etiology*; D002726:Chlorogenic Acid / Q000008:administration & dosage / Q000009:adverse effects*; D003069:Coffee / Q000009:adverse effects / Q000737:chemistry; D018592:Cross-Over Studies; D005215:Fasting; D005260:Female; D005419:Flavonoids; D005492:Folic Acid / Q000097:blood; D005960:Glucosides / Q000008:administration & dosage / Q000009:adverse effects*; D006710:Homocysteine / Q000097:blood* / Q000187:drug effects; D006801:Humans; D008297:Male; D010636:Phenols / Q000008:administration & dosage / Q000009:adverse effects*; D011108:Polymers / Q000008:administration & dosage / Q000009:adverse effects*; D019518:Postprandial Period; D011736:Pyridoxine / Q000097:blood; D011794:Quercetin / Q000008:administration & dosage / Q000009:adverse effects* / Q000031:analogs & derivatives*; D012307:Risk Factors; D013662:Tea / Q000009:adverse effects / Q000737:chemistry; D014805:Vitamin B 12 / Q000097:blood
D003069:Coffee; D005419:Flavonoids; D005960:Glucosides; D010636:Phenols; D011108:Polymers; D013662:Tea; D006710:Homocysteine; D002726:Chlorogenic Acid; D005492:Folic Acid; D011794:Quercetin; D011736:Pyridoxine; D014805:Vitamin B 12