Evaluation of dietary intake using carbon and nitrogen isotope analysis of human hair of Chinese living in southern part of China.

We examined dietary intakes among 69 people of three ethnic groups (Yao Chinese, Zhung Chinese and Han Chinese) in the autonomous country of Bama in China where many elderly people have a long life span in 1998. Dietary intake was evaluated using carbon and nitrogen isotope ratios of human hair (delta 13C, delta 15N) standardized by standard gas. The distributions of delta 13C in Yao Chinese and Han Chinese were scattered from -21 to -17/1000, which were close to that of C4 plants such as corn and millet. The distribution of delta 13C in Zhung Chinese was located from -25 to -22/1000, which was near that of C3 plants such as rice, wheat and potato. These values showed a much wider range when compared with delta 13C in Chinese living in urban areas. On the other hand, delta 15N in each group was distributed in the area ranged from 8 to 11/1000. The result of delta 13C was consistent with data obtained from a nutritional survey, but that of delta 15N was a little higher than expected. The carbon and nitrogen isotope ratios of human hair among three ethnic groups showed characteristic distributions, although the relation between these isotope ratios and longevity is uncertain.