Coffee drinkers seem to be at increased risk of developing rheumatoid arthritis, suggests research in the Annals of the Rheumatic Diseases.
The association between coffee drinking and the presence of a hallmark indicator for the development of rheumatoid arthritis "rheumatoid factor" was studied in a cross sectional survey of almost 7,000 people, and in almost 19,000 people who were monitored for around 15 years. None of the study participants had any evidence of arthritis when first tested.
The number of cups of coffee drunk daily was strongly associated with rheumatoid factor in the survey study. In the second larger study, those people who drank four or more cups of coffee a day were twice as likely to test positive for arthritis than those who drank less. The results held true even after adjusting for other risk factors, such as age, gender, smoking, and weight. Those who drank 11 or more cups a day were almost 15 times as likely to have rheumatoid factor as non-coffee drinkers.
The authors conclude that some as yet unidentified ingredient in coffee, particularly in coffee that is not filtered, may trigger the production of rheumatoid factor, which can precede the development of arthritis by years, and consequently lead to an increased risk of developing rheumatoid arthritis.