Relationship between Regional Distribution of Centenarians and Drinking Water Hardness in the Amami Islands, Kagoshima Prefecture, Japan

A strong correlation exists between drinking water hardness and the rate of centenarians in Japan's Amami Islands, suggesting that hard water—particularly from coralline limestone bedrock—may enhance longevity. The study analyzed four islands (Amami-Oshima, Tokunoshima, Okinoerabu, and Yoron), finding that water hardness, primarily determined by calcium and magnesium content, closely mirrored the distribution of centenarians. Yoron Island, with predominantly coralline limestone bedrock, reported the highest centenarian rate (29.7 per 10,000) alongside the hardest water, while Amami-Oshima, lacking such bedrock, had the lowest rates (0.0 to 12.2). The findings propose a potential cardiovascular benefit from hard water, contributing to ongoing discussions on global drinking water quality and its impact on health.

Suzuki, M., Wu, S., Ootawa, T., Smith, H., Shiraishi, M., Miyamoto, A., Matsuoka, Y., Sawa, S., Mori, M., Mori, H., & Yamori, Y. (2023). Relationship between Regional Distribution of Centenarians and Drinking Water Hardness in the Amami Islands, Kagoshima Prefecture, Japan. Nutrients, 15(7), 1569. https://doi.org/10.3390/nu15071569