According to a study, women who drink tea have an increased risk of developing rheumatoid arthritis compared with those who drink none (p=0.04). Further results from the same study showed no correlation between the amount of coffee consumption and rheumatoid arthritis incidence (p=0.16).
The results of the US based longitudinal cohort study involving 76,643 women showed a positive association of incident rheumatoid arthritis in tea drinkers with an increasing Hazard Ratio (HR) observed alongside tea consumption (p=0.03). Consuming any amount of tea carried a significant risk of developing rheumatoid arthritis (HR 1.40 (95%CI 1.01-1.93) p=0.04) and women who drank ?4 cups of tea per day had an increased risk of developing rheumatoid arthritis compared to those who drank none (HR 1.78 (95%CI 0.83-3.82)). An analysis of the method of preparation of coffee (filtered vs unfiltered) and presence or lack of caffeine in the beverage did not show any significant associations with rheumatoid arthritis or Systemic Lupus Erythematosus (SLE, an autoimmune disease in which the immune system harms the body’s own healthy cells and tissues) (rheumatoid arthritis: filtered p=0.08, unfiltered p=0.38, SLE: filtered p=0.74, unfiltered p=0.97). No increase was shown in the risk of developing rheumatoid arthritis in participants who drank coffee compared to those that did not (rheumatoid arthritis: HR 1.09 (95%CI 0.77-1.54 p=0.63).
“We set out to determine whether tea or coffee consumption, or the method of preparation of the drinks was associated with an increased risk of rheumatoid arthritis or SLE – it is surprising that we saw such differences in results between tea and coffee drinkers,” said Professor Christopher Collins. “This does make us wonder what it is in tea, or in the method of preparation of tea that causes the significant increase in risk of developing rheumatoid arthritis.”
Data on women aged 50-79 were taken from the Women’s Health Initiative Observational Study database (a major 15-year research program to address the most common causes of death, disability and poor quality of life in postmenopausal women) where participants completed a self-administered questionnaire providing information on daily consumption of coffee and tea.
The relationships between drinking tea and coffee and the risk of rheumatoid arthritis or SLE were assessed in age-adjusted models and in multivariate Cox proportional hazard models (a statustical approach to estimating survival data). At three years follow up, the diagnosis of incident rheumatoid arthritis was determined using self-reporting and respondent’s feedback on use of disease modifying anti-rheumatic drugs (DMARDS). The variables studied in the rheumatoid arthritis population were also investigated in women with SLE, but no significant associations were found.
“These are very interesting findings and we hope that additional research will investigate this topic further. We do assert the need for caution in the interpretation of these findings as no strong causation effect has been confirmed, and encourage patients with rheumatic diseases to consult their physician before making any significant changes to their diet or caffeine intake” said Professor Paul Emery, President of European League Against Rheumatism.