Contribution of Caffeine to the Homocysteine-Raising Effect of Coffee: A Randomized Controlled Trial in Humans

Introduction

• Study Focus: Investigating the homocysteine-raising effect of coffee and the contribution of caffeine to this effect.
• Health Context: Elevated plasma homocysteine levels are linked with increased risk of cardiovascular diseases.

Objective

• Determine whether caffeine is the component in coffee responsible for increasing homocysteine levels.

Study Design

• Type: Randomized crossover study.
• Participants: 48 subjects aged 19-65 years.
• Duration: Each treatment lasted for 2 weeks.
• Treatments:
  • 6 capsules with 870 mg caffeine/day (test treatment)
  • 0.9 L paper-filtered coffee (providing ~870 mg caffeine/day)
  • 6 placebo capsules
• Blood Samples: Collected fasting and 4 hours post-consumption of 0.45 L coffee or 3 capsules.

Results

• Placebo Treatment: Fasting plasma homocysteine concentration was 9.6 ± 3.1 micromol/L.
• Caffeine Treatment:
  • Increased homocysteine by 0.4 micromol/L (5% increase; P = 0.04).
  • Acute effect: 4% increase (P = 0.09).
  • Stronger effects observed in women than in men.
• Coffee Treatment:
  • Increased homocysteine by 0.9 micromol/L (11% increase; P = 0.0001).
  • 19% increase 4 hours after consumption relative to placebo (P = 0.0001).
  • Effects did not differ significantly between men and women.

Conclusions

• Caffeine is partly responsible for the increase in homocysteine levels after coffee consumption.
• Coffee impacts homocysteine metabolism significantly within hours of intake and remains substantial after fasting overnight.

Similar Studies

1. Heavy coffee consumption effects on plasma homocysteine.
2. Chlorogenic acid and black tea's impact on plasma homocysteine.
3. Unfiltered coffee's impact on plasma homocysteine.

Key References

• Clinical trial identification: PMID 12450889; DOI: 10.1093/ajcn/76.6.1244.
• Authors: Petra Verhoef, Wilrike J Pasman, Trinette Van Vliet, Rob Urgert, Martijn B Katan.
• Affiliation: Wageningen Centre for Food Sciences, Nutrition and Health Programme, Netherlands.

Additional Notes

• The study highlights the significance of identifying dietary contributors to homocysteine levels to better manage cardiovascular risk.