Ramen restaurant prevalence is associated with stroke mortality in Japan: an ecological study

BACKGROUND: The association between stroke and nutrition has recently been investigated. However, the association between diet and stroke in Japan has not been clarified. We hypothesized that there may be an association between consumption of ramen and stroke mortality. Therefore, we investigated the association between the prevalence of ramen restaurants and stroke mortality in Japanese prefectures. METHODS: We used Pearson’s correlation coefficients to evaluate associations between the prevalence of each of four restaurant types (ramen, fast food, French or Italian, and udon or soba) and age- and sex-adjusted stroke mortality rates in each prefecture. We also investigated correlations between acute myocardial infarction and the prevalence of each type of restaurant as a control. We obtained age- and sex-adjusted stroke mortality rates and the acute myocardial infarction mortality rate in each prefecture from the 2017 Trends in National Health published in Japan. Data on the number of restaurants of each type in each prefecture were obtained from the database of the Nippon Telegraph and Telephone Corporation. RESULTS: The prevalence of ramen restaurants, but not of other restaurant types, positively correlated with stroke mortality in both men and women (r > 0.5). We found no correlation between ramen restaurant prevalence and mortality from acute myocardial infarction. CONCLUSION: The prevalence of ramen restaurants in Japanese prefectures has a significant correlation with the stroke mortality rate. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12937-019-0482-y) contains supplementary material, which is available to authorized users.