Based on the results of a genome-wide association analysis (GWAS) related to coffee drinking habits, a Japanese research group has performed a Mendelian randomization analysis (MR analysis) on the results of the largest Japanese GWAS of serum uric acid levels and the largest Japanese GWAS of gout in cases where it was diagnosed by a doctor, respectively, examining two causal relationships: coffee drinking habits and serum uric acid levels, and coffee drinking habits and the onset of gout. The group was led by Dr. Yuya Shirai and Professor Yukinori Okada from the Graduate School of Medicine, Faculty of Medicine, Osaka University, Lecturer Masaki Nakayama, Medical Officer Yusuke Kawamura, and Professor Hirotaka Matsuo of the Department of Integrative Physiology and Bio-Nano Medicine, National Defense Medical College.
The group found that habitually drinking coffee reduces the risk of developing gout in Japanese people, independent of fluctuations in serum uric acid levels. Previous observational studies have reported a correlation between coffee drinking and a decreased risk of developing gout, but the details of this correlation were not clear. Nakayama said, "Since Japan had conducted the largest genome-wide association analysis of coffee intake and serum uric acid levels and gout, we performed an MR analysis using these genome-wide association analyses to examine the preventive effect of coffee on gout and its causal relationship."
The research group conducted the MR analysis based on the results of a GWAS related to coffee-drinking habits in about 150,000 Japanese subjects and the results of a GWAS of serum uric acid levels in about 120,000 Japanese subjects, and the results of a GWAS of gout in about 3,000 clinically diagnosed gout cases in Japanese men, respectively. The group then examined two causal relationships: coffee drinking habits and serum uric acid levels, and coffee drinking habits and onset of gout. The results of this research are the first in the world to show through accurate statistical analysis that coffee drinking can prevent gout, which is on the rise in Japan due to lifestyle changes caused by the Westernization of diets and other factors.
Nakayama said, "Our results suggest that coffee has a preventive effect on gout attacks without affecting uric acid levels. We hope to use this to elucidate the mechanisms behind attacks of gout and the development of new drugs for preventing this condition."
■ Mendelian Randomization Analysis (MR Analysis): A statistical method that uses genomic information such as GWAS to estimate the causal relationship between environmental factors of interest (in this study, coffee drinking habits) and risk of disease (gout).