Is Coffee Good or Bad? - Another Piece of Evidence

Summarized by Robert W. Griffith, MD
November 10, 2004

Introduction

There have been innumerable studies that looked for serious ill effects of caffeine on people's health. For the most part, they have come up empty handed. The physiological effects of large doses of caffeine - palpitations, jitteryness, increased urination - are well-known. Also, an increase in blood pressure can occur. On the other hand, caffeine has been reported to improve brain function in people over 80, and, maybe, lower the likelihood of diabetes.

A study conducted in Greece has now found an association between coffee intake and increased levels in the blood of four inflammatory markers - C-reactive protein (CRP), serum amyloid-A (SAA), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) - that are usually found in people with obesity, insulin resistance, coronary heart disease, and the metabolic syndrome. Here's a summary of the publication in the American Journal of Clinical Nutrition.

What was done

The study was carried out in the Greek province of Attica, which includes Athens. Over 1500 men and 1500 women were enrolled. Any subjects with cardiovascular disease, atherosclerotic disease, or chronic viral infections were excluded. People with colds, acute respiratory infections, and dental problems were also eliminated.

A food-frequency questionnaire was used to estimate the average daily consumption of a variety of foods and drinks, including coffee. The subjects were classified into groups, according to whether their coffee intake was:
   none,
   rare - 100 mL/day or less,
   moderate - 200-400 mL/day, or
   heavy - over 400 mL/day.
All types of coffee were adjusted for 1 cup of coffee to equal 150 mL, with a concentration of 28 mg caffeine/cup.

Fasting blood samples were taken from all the participants, and examined for CRP, SAA, IL-6, and TNF-α. In addition, blood lipids and white blood cell counts were determined.

What was found

Interestingly, moderate coffee drinking was associated with higher blood pressure readings in men, and lower readings in women, compared with non-coffee drinkers. Total cholesterol levels were higher in coffee drinkers of both sexes, in a 'dose-dependent' fashion - the greater the coffee intake, the greater the rise in cholesterol.

In men, those who drank over 200 mL coffee per day (over 1-and-1/3 cups) had 50% higher IL-6, 30% higher CRP, 28% higher TNF-α, and 12% higher SAA levels than those who drank no coffee. Women drinking over 200 mL coffee per day had 54% higher IL-6, 38% higher CRP, and 28% higher SAA and TNF-α than non-coffee drinkers. Those participants of either sex who drank more than 400 mL coffee per day had even greater increases of these inflammatory markers.

In addition to these changes, white blood cell counts were 3% higher in male and 4% higher in women coffee drinkers. All these findings were still present after adjustments were made for differences in age, smoking, body mass index, and physical activity.

What does this mean?

This study found that coffee drinking was associated with an increase in all the inflammatory markers measured. Previous reports have noted associations between coffee consumption and disturbances of heart rate, heart rhythms, blood pressure, serum cholesterol, and thereby cardiovascular risk. Although some of these associations can be explained by the pharmacological effect of caffeine, the increase in inflammatory markers found here suggests the possibility that coffee may indeed have a more intrusive effect than thought until now.

Inflammatory markers are indicators of low-grade inflammation occurring in the body. Several reports indicate that they can predict the occurrence of cardiovascular events (such as heart attack or angina) in older people.

It looks from this study that increases in inflammatory markers can be detected with as little as 1-2 cups of coffee a day, if taken regularly. It's hard to believe that this amount of coffee drinking is actually linked to a relevant increase in cardiac events. Nevertheless, as it appears to be a 'dose-dependent' effect, it might be wise to limit your coffee intake to some extent, especially if you get a rapid heart rate or palpitations.

Source

• Associations between coffee consumption and inflammatory markers in healthy persons: the ATTICA study. A. Zampelas, DB. Panagiotakos, C. Pitsavos,  et al., Am J Clin Nutr, 2004, vol. 80, pp. 862--867

Related Links
Study Shows Coffee Not Hazardous to Heart Health
Coffee May Actually Be Good For You!
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