People who drink four or more cups of coffee per day are significantly more likely to get rheumatoid arthritis than are people drinking less, scientists in Finland report in the August Annals of Rheumatoid Diseases.
The researchers analyzed the habits of 18,981 adults between the early 1970s and 1989. Mobile health-examination teams of nurses had amassed data on lifestyle and diet in four areas of Finland. The coffee study included only participants who were free of rheumatoid arthritis at the start.
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By 1989, only 0.4 percent of 4,641 people who drank three cups of coffee or less per day had rheumatoid arthritis, whereas 0.8 percent of 14,340 people drinking 4 or more cups had developed the disease, says study coauthor Markku Heliövaara, a physician and epidemiologist at the National Public Health Institute in Helsinki.
The link was even stronger between heavy coffee intake and the kind of rheumatoid arthritis that is accompanied by rheumatoid factor, an antibody that appears in the blood of 70 to 80 percent of arthritis patients. Scientists don’t fully understand the antibody’s role,
Heliövaara says, but they know its emergence often precedes disease symptoms by years. The researchers accounted for alcohol intake, body weight, smoking, and blood cholesterol concentrations in calculating the correlation between coffee drinking and arthritis.
Nevertheless, the researchers admit they can’t conclude that increased risk of disease is directly attributable to greater coffee consumption and not some closely linked lifestyle or dietary factor that escaped detection. “Our results should be viewed as the first step in support of the hypothesis that coffee consumption has a causative role,” Heliövaara says.