A medical survey was conducted in 3 settings in Ladakh, India to reveal the health status of the people dwelling
in the central town, Leh （3600m ASL）, nomads in the Changthang plateau （4200-4900m ASL）, and farmers in the
Domkhar valley （3000-3800 ASL）. As a result, we found；1） a higher prevalence of lifestyle-related diseases such
as diabetes and hypertension in the urbanized towns, 2） a correlation between higher altitude and higher blood sugar
levels, 3） a prevalence of diabetes among both the people who had higher energy intake and higher hemoglobin levels,
and among the people who had lower energy intake and lower hemoglobin levels. Finding 1） might be explained by
epigenetics and the Thrifty gene, but no simple explanation exists for findings 2） and 3）. The long lasting process of
adaptation to the low oxygen environment might play a role.
According to Beallʼs studies, Tibetans have adapted to the low oxygen levels via a “blood flow increase” mechanism
caused by vasodilation, which increases pulmonary vital capacity and adjusts respiratory response. Meanwhile, Andeans had adapted to the low oxygen levels via a “hemoglobin increase” mecanism.
Some of our findings echo Beallʼs hypotheses. However, polycythemia （high hemoglobin level） was observed
even in the case of the elderly people in Leh and Domkhar where the lifestyle has come to change. This phenomena
contradicts Beallʼs hypotheses.
Our study has investigated into the cause of the discrepancy. As a result, we attempt to elucidate actual situation
of oxidative stress in highlanders and its relation to the low oxygen, and also the association between oxidative stress
and diabetes. We hypothesize that the Tibetan highlanders had adapted to the low oxygen by increasing blood flow
and vasodilation by increasing nitrogen levels. However with aging, they lose their adaptation balance. Combined
with the drastic changes in lifestyle and appearance of obesity, the excessive nitrogen works to increase the oxidative
stress. This effect might accelerate the occurrence of diabetes. Diabetes and oxidative stress tend to affect each other
and worsen symptoms.
雑誌名
放送大学研究年報 = Journal of The Open University of Japan
巻
32
ページ
69 - 79
発行年
2015-03-20
出版者
放送大学
ISSN
0911-4505
書誌レコードID
AN10019636
論文ID（NAID）
40020473114
著者版フラグ
publisher
放送大学機関リポジトリとは
放送大学機関リポジトリ（The Open University of Japan Repository）では、放送大学で生産された学術成果を収集・蓄積し、広く公開しています。
ヒマラヤ・ラダーク地方における高所適応とその変容 (2) 生活習慣病を中心に
ヒマラヤ・ラダーク地方における高所適応とその変容（2）生活習慣病を中心に
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