Does drinking coffee impact homocysteine concentrations? - Food and Health - Brief Article

Nutrition Research Newsletter, Oct, 2001

The relationship between coffee consumption and health has long been of interest to both coffee drinkers and health professionals. In the past, there was some early observation that indicated a relation between the occurrence of ischemic heart disease and coffee intake; however, these results were inconsistent. There has been some recent inconclusive evidence indicating a relationship between coffee consumption and homocysteine concentrations. Elevated levels of homocysteine are a risk factor in the development of artery disease. Evidence also exists showing that very high intake of unfiltered coffee, but not filtered coffee, can increase plasma total homocysteine (tHcy) concentrations by as much as 10%.

In an effort to assess the coffee-tHcy as well as the coffee-total cholesterol association, researchers performed a randomized intervention trial, controlling for both dietary habits and brewing methods. The study was a prospective, unblended controlled trial with participants randomly assigned to the different treatment groups. Because of the knowledge that cigarette smoking is associated with low folate concentrations and thus elevated tHcy concentrations, only nonsmokers were used as subjects. Approximately 180 participants, aged 24-69 years, completed the trial. The subjects were randomized into one of the following six-week treatment regimens: 1) instructed to consume no coffee; 2) instructed to consume one to three cups of coffee per day; 3) or instructed to consume greater than four cups of coffee per day. All subjects were asked to follow their usual diet during the trial. The coffee-consuming groups were permitted to drink the type of coffee to which they were accustomed. Body weight and blood pressure were monitored throughout the intervention period. Dietary habits were recorded at the start and end of the trial. Nonfasting blood samples were drawn at the time of randomization and at 3 and 6 weeks after the start of the trial. Folate, tHcy, vitamin B-12, and lipid concentrations were analyzed.

Ninety-seven percent of all participants reported regularly drinking caffeinated, filtered coffee prior to intervention. The abstention from coffee consumption for six weeks was associated with an average decrease in total cholesterol of 0.28 [micro]mol/L and a decrease in tHcy of 1.08 [micro]mol/L compared with the initial concentration. In the two groups that drank coffee during the intervention, the changes in total cholesterol, tHcy, and serum folate concentrations were not significant after six weeks. There were no significant trends in whole blood folate seen. Also, the concentration of vitamin B-12 in serum did not change in any of the groups.

This data illustrates that giving up filtered coffee in doses that are commonly consumed appears to be associated with lower concentrations of both tHcy and total cholesterol.

B. Christensen, A. Mosdol, L. Retterstol, et al. Abstention from filtered coffee reduces the concentrations of plasma homocysteine and serum cholesterol--a randomized controlled trial. Am J Clin Nutr; 74:303-307 (September 2001) [Correspondence: B. Christensen, Dept. of Medical Genetic, Ulleval University Hospital, N-0407 Oslo, Norway. E-mail: benedicte.chrestensen@ioks.uio.no].