Coffee consumption and blood homocysteine
Homocysteine and cardiovascular disease risk
Homocysteine is a naturally occurring amino acid found in the blood and tissues. However, it is not among the twenty amino acids which are the building blocks of proteins and, hence, is not found in dietary protein. Several factors influence plasma homocysteine levels, such as intake of folic acid and vitamin B12, age, gender, heredity, smoking, hypertension and physical activity19.
It was first suggested back in 1999 that elevated levels of homocysteine in the blood are associated with a higher risk of cardiovascular disease20. However, not all studies have been able to demonstrate this association21,22. It is still unclear whether reducing high homocysteine levels will lead to a lower risk of cardiovascular disease. In addition, no causal relationship has been established between high total plasma homocysteine levels (tHCYs) and cardiovascular disease23.
Coffee, caffeine and homocysteine
Intervention studies have shown that high levels of coffee consumption (6 to 10 cups of coffee per day) increase tHCYs24,25, and tHCYs decrease if regular coffee consumers stop drinking coffee26. However, a study based on 5 cups of espresso a day did not show a significant effect of tHCYs27, possibly because of the smaller volume consumed.
It has been suggested that caffeine may be partly responsible for the effect of coffee on tHCYs28, but the presence of chlorogenic acid in coffee can also contribute to the effect on homocysteine29.