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

Abstract

People who drink naturally hardened water may experience longevity-enhancing effects. In this study, we investigated water hardness and longevity from both geological and epidemiological perspectives in Japan’s Amami islands, where drinking water is drawn from coralline or non-coralline bedrock. We investigated drinking water hardness, limestone bedrock occupancy, and the centenarian rate (number per 10,000 population) by municipality across four adjacent islands (Amami-Oshima (non-coralline), Tokunoshima, Okinoerabu, and Yoron (predominantly coralline)). Limestone was strongly correlated with water hardness (r = 0.99; p < 0.01), occupying more than 80% of the bedrock where the water was the hardest (Tokunoshima’s Isen municipality: 86.5%; Yoron: 82.9%) and being scarcely detectable in Amami-Oshima (0.0 to 0.2%), where the water was the least hard. The centenarian rate was also strongly correlated with water hardness (r = 0.84, p < 0.01), with the highest figures in Yoron (29.7) and Isen (29.2), and the lowest in Amami-Oshima (0.0 to 12.2). Therefore, we hypothesize a potentially beneficial effect of hard water on longevity when that water is drawn from coralline limestone. Water hardness is determined by the water content of calcium and magnesium and may plausibly influence life expectancy through a preventative effect against cardiovascular disease. Our findings are of interest to current debates about future global access to drinking water and its quality.

Nutritional Barriers to the Adherence to the Mediterranean Diet in Non-Mediterranean Populations

“…Faith, family and a purposeful life, plan de vida , are part of the lifestyle on the Nicoyan peninsula [ 44 , 46 ]. Longevity related to a diet resembling the Blue Zone and Mediterranean diets, lifestyle and environment was observed in Bama, China [ 47 ] and in the Amami Islands, Japan [ 48 ]. The high mineral content of the soil and hard-water characteristics of the Amami Islands may also provide important cardioprotective benefits to residents [ 44 , 47 , 48 ].…”

“…Longevity related to a diet resembling the Blue Zone and Mediterranean diets, lifestyle and environment was observed in Bama, China [ 47 ] and in the Amami Islands, Japan [ 48 ]. The high mineral content of the soil and hard-water characteristics of the Amami Islands may also provide important cardioprotective benefits to residents [ 44 , 47 , 48 ]. In the US, the Adventists have active daily lives and consume a vegetarian diet that ranges from vegan to lacto-vegetarian, rich in green leafy vegetables, nuts and legumes [ 49 , 50 ].…”

“…The practice of Moai, which places individuals in secure social networks formed from as early as the age of 5, the 80% rule of Hara Hachi Bu repeated at mealtimes to prevent overeating and a strong sense of purpose contribute to the longevity and the reduced levels of neurodegenerative disease and other diseases of inflammation [ 53 , 54 , 55 ]. A high number of centenarians are found in the Amami Islands in Japan, which are characterized by the availability of hard water rich in calcium and magnesium, considered an important factor contributing to longevity among residents [ 48 ]. All five Blue Zones share the same nutrients found in the Mediterranean diet that benefit health and that contribute to longevity, and all the zones have in common foods, calorie restriction associated with small to moderate food portions and cultural practices that are unfamiliar to populations outside the zones; in particular, populations in the US may associate or interchange the Mediterranean diet with Blue Zone diets.…”

Habu snakes (<i>Protobothrops flavoviridis</i>) show variation in thoracic aortic vasoreactivity between adjacent Japanese islands

“… ). The islands share a broadly identical climate and are separated by a distance of approximately 45 km [ 38 ]. We harvested tissue from a total of 22 Habu snakes ( Fig.…”

“…Factors influencing vasoreactivity include nutrition, and general health and parasite burdens. With regard to nutrition, we cannot comment on prey species for the Habu snakes in the two islands, but the water on Tokunoshima is known to have higher calcium and magnesium ion concentrations [ 38 ], due to the island’s coralline limestone basement (a geological feature absent from Amami-Oshima) [ 20 ]. The resultant difference in mineral intake could plausibly have some biogeographical manifestation, reflected in varied vasoreactivity.…”