Neurons and Exercise

Neurons and Exercise

Wednesday, August 5, 2020

Sixth Blue Zone - West Hechi, China


Discovering the Sixth Blue Zone

When my second book “Silica Water the Secret of Blue Zone Longevity in the Aluminum Age” was published in the fall of 2018 I had discovered only 5 demographically documented blue zones.  While visiting the Boston Science Museum’s “Body Worlds” exhibit in the summer of 2019 my wife, Laurie Adamson, pointed out a display panel of Blue Zones that had two new zones: one in Pakistan and one in China. 

I quickly checked and found that the Blue Zone in Pakistan has not been documented due to a lack of birth records.  However, the Blue Zone in West Hetchi, China that is referred to as “Bama Yao” has been verified by two teams of demographers as having a much higher centenarian density that neighboring regions.  In 2018 this demographic data was supplemented with two additional studies that led to a remarkably simple conclusion that the only reason discovered for Bama Yao being a blue zone is the high silica in drinking water as compared to neighboring regions.

I have added the following section on West Hetchi, China as a 6th blue zone to the book and will have a second printing in the fall of 2019.  These 2018 studies provide more support for the conclusion of my second book that OSA rich drinking water is a causal factor of longevity.  Of course I would be compelled to add this 6th blue zone, even if these studies did not support this conclusion.            
West Hechi, China
Hechi is a prefecture located in the north of the Guangxi region of China (see Figure 21). This prefecture is in southern China on the border with Viet Nam. In western Hechi there are three adjacent counties with much higher centenarian prevalences and longevity indexes than three adjacent counties to the east in central Hechi. The longevity counties are: Bama Yao, Fengshan, and Donglan with Bama Yao being a super blue zone having the highest longevity index. The non-longevity counties are: Huanjiang, Jinchengjiang, and Nandan. The Duyang Mountains separate the longevity counties from the non-longevity counties (see Figure 21). 


Figure 21 – Location of Hechi and its sampling sites (c) in Gurangxi (b), China (a) 461

Bama Yao Blue Zone Verification – In 1992 Yang used data from the 1990 census and from a questionnaire survey conducted in Bama Yao to analyze the population age 80 and over462. In May to June of 1994 three Chinese demographers evaluated the quality of Yang’s survey data by interviewing 67 out of 73 people over age 100 in Bama Yao463.  Age records were available from birth registers and generation rankings. They found that only 3 centenarians still had spouses and 42 were women and 25 were men.  The people of Bama Yao are comprised of 13 ethnic groups with 17.4% being Yao. The centenarian prevalence in the Yao population was 79.4 per 100,000 which indicated that Bama Yao is a blue zone. The demographers found Yang’s survey data to be reliable. 


Air Quality in Bama Yao - The centenarian prevalence and the longevity index of 31 regions in China, including Guangxi, were evaluated in 2016 with respect to air quality parameters464. Sulfur dioxide and particulates in the air 10nm or smaller were negatively correlated with centenarian prevalence and the longevity index, respectively. The three longevity counties and three non-longevity counties in Guangxi, including Bama Yao, are located in remote mountainous areas (see Figure 21) and therefore their air quality is well above average. Because all six counties have the same air quality it is not possible that air quality is a factor in the observed longevity in Bama Yao.

Natural and Socioeconomic Factors in Bama Yao – Natural factors, such as temperature and altitude, and socioeconomic factors, such as GDP, economic status, education, local infrastructure, and health care facilities were evaluated spatially and geographically with respect to 7 longevity indicators, including centenarian prevalence and longevity index, in 109 selected counties and districts in Guangxi465. The results indicated only a weak association with longevity and natural factors, such as temperature and altitude, and socioeconomic factors, such as GDP per capita. However, the average GDP in Hechi was comparatively lower than other regions in Guangxi461.   All the longevity and non-longevity counties in West Hechi have similar topography and temperatures. Therefore, there is no natural of socioeconomic factor that stands out as being a contributor to the longevity observed in Bama Yao.
Environmental Factors in Bama Yao – Trace elements in the soil and drinking water of Hechi were evaluated temporally and spatially with respect to centenarian prevalence and longevity index from 1982 to 2010461.  The trace elements measured in the drinking water sampled from 40 locations were: Pb, Zn, Cd, SO42-, Mn, H2SiO3, Ca, Fe, Na, Mg, Li, Mo, and Se. The trace elements measured in soil were: Sr, K, Mo, Fe, Co, Zn, Cu.  The only trace element in soil and drinking water that showed a significant (0.01 level) positive correlation with both centenarian prevalence and longevity index is H2SiO3. This trace element forms a hydrate in water called OSA (H4SiO4).  For details see Table 4 at the beginning of this chapter.


The following paragraph is taken from the paper linking OSA to longevity in the three longevity counties, including Bama Yao461: “As many centenarians live in rocky areas466, most of the members of the longevity population in Hechi use the underground water source as their primary water supply. These areas do not have much surface water but do have abundant quantities of underground water from underground caverns. For example, in 1982, 1990, and 2000, approximately 75% of the centenarians in Bama County lived in rocky and semi-rocky areas and used underground water as their main water source, and approximately 30% of the underground water areas have sustained approximately 70% of the centenarians in Bama over decades467. It can be inferred that the distinctive tectonic settings of Hechi might have long-term impacts on longevity in this region“.
Distinctive Tectonic Setting of West Hechi
The tectonic setting of western Guangxi has been studied468. The Duyang Mountains that separate the longevity from the non-longevity counties in Hechi lie along a geological rift. Rifts occur linearly along the central axis of most mid-ocean ridges where two tectonic plates are diverging and literally pulling apart the earth’s crust. The result is a long wide valley to the west of the Duyang Mountains where the three longevity counties are located called the Danchi Rift Trough468. This area is distinctive because drinking water in this area is significantly higher in OSA than the area just to the east of the Duyang Mountains461.
Deep-water ocean sediments from the late Early Devonian to the late Permian have been uplifted in the Danchi Rift Trough. The rocks in this area are mostly chert containing greater than 70% silicon dioxide (SiO2) derived from non-terrigenous (i.e. marine) sediments468. Sources of these marine sediments can be of either biogenic or hydrothermal origin. The chert that underlies Bama Yao is from the Middle Permian period469.
The source of silica in this cert is predominantly biogenic being derived from siliceous organisms such as radiolarians, diatoms, and siliceous sponges468. This cert is richer in SiO2 than modern oceanic siliceous sediment and less rich in SiO2 as compared with the nearly pure SiO2 in chert from terrigenous sources, such as volcanos468. Enrichment of biogenic SiO2 in chert is hypothesized to occur by a process called diagenetic silicification that more than doubles the SiO2 in chert470. In this process water enriched in OSA displaces calcium carbonate in chert making biogenic SiO2 (a.k.a. opal)471.
Opal is a good source of OSA as it is the most soluble solid silicate in sediments472. When water becomes in contact with different types of opal sediments at pore depths greater than 10cm the equilibrium concentration of OSA in the water is from 9.6 to 72ppm (100 to 750 mcM L-1)472. The unique conditions required for diagenetic silicification resulting in opal deposits may account for the unique OSA rich well water found in the Danchi Rift Trough.    
References
461. Deng, Q., et al.; Understanding the association between environmental factors and longevity in Hechi, China: A drinking water and soil quality perspective; Int. J. Environ. Res. Public Health; 15:2272:1-17 (2018)

462. Yang, J.; An analysis of the longevous population in Bama; Chin. J. Popul. Sci.; 4(4):351-6 (1992)
463.Xiao, Z., et al.; Solving the mystery of the status and longevity of centenarians in Bama; Chin. J. Popul. Sci.; 8(4):385-94 (1996)
464.Song, W., et al.;  Public health in China: An environmental and socioeconomic perspective; March; 129:9-17 (2016)
465.Deng, Q., et al.; Understanding the natural and socioeconomic factors behind regional longevity in Guangxi, China: Is the centenarian ratio a good enough indicator for assessing the longevity phenomenon?; Int. J. Environ. Res. Public Health; 15:938:1-16 (2018)
466.Zhang, N,, et al.; Study on regional distribution of longevity and the hair’s chemical elements content of the crowds in Bama county, Guangxi province; Clin. J. Gerontol.; 9, 050 (2010)
467.Liang, Z.; Understanding the longevity phenomenon in Bama; China Stat.; (2004)
468.Hu, H., et al.; Depositional chemistry of chert during the late Paleozoic from western Guangxi and its implication for the tectonic evolution of the Youjiang Basin; Sci. China Earth Sci.; March; doi: 10.1007/s11430-012-4496-y (2012)
469.Qiu, Z., et al.; Geochemistry and sedimentary background of the Middle-Upper Permian cherts in the Xiang-Qian-Gui region; Acta. Petrol. Sin.; 26:3612-28 (2010)
470.Murray, R.W., et al.; Diagenetic formation of bedded chert: Evidence from chemistry of the chert-shale coupler; Geology; 20:271-4 (1992)
471.Bustillo, M.A.; Chapter 3 Silicification of continental carbonates; Dev. Sedimentology; Dec.; 62  doi: 10.1016/S0070-4571(09)06203-7 (2010)
472.  Martin, W.R. and Sayles, F.L.; The recycling of biogenic material at the seafloor; Section 7.02.6.1 Dissolved silica profiles in pore waters; Treatise on Geochemistry; (2003)