Biochemical analyses were conducted to evaluate the nutritional status of a high
esophageal cancer risk population in Linxian, People's Republic of China. A study was conducted in September 1980 in which plasma levels of
vitamins A, B2, and C were analyzed. In a second study in 1983, the plasma fat-soluble
vitamins were analyzed with a newly developed high-performance liquid chromatography method that allowed the simultaneous determination of
retinol,
alpha-tocopherol,
beta-carotene,
alpha-carotene, and
lycopene in 0.1 ml of plasma sample. The average plasma
retinol levels ranged from 24 to 27 micrograms/dl among the population groups, with 20-35% of the individuals having levels under 20 micrograms/dl. Low plasma
beta-carotene levels averaging 8-12 micrograms/dl were observed among the population groups. Low plasma
alpha-tocopherol levels with average values around 700 micrograms/dl were also observed; about half the individuals were either low or deficient in
vitamin E. After 4 months of supplementation with daily multivitamin
tablets, the plasma contents of
retinol and
alpha-tocopherol were significantly increased. The plasma
alpha-carotene and
beta-carotene were also increased, possibly as a reflection of seasonal changes in the diet or a sparing effect of
vitamins A and E on these
carotenes. Low plasma ascorbate levels with an average of 567 micrograms/dl were observed, and about 23% of the individuals had values under 200 micrograms/dl.
Riboflavin deficiency was prevalent, with about 90% of the subjects having an erythrocyte
glutathione activation coefficient over 1.2. The study establishes the low nutritional status in
vitamins of the population in Linxian and provides the background for further studies on the effects of
nutritional deficiency on
carcinogenesis.