Vitamin A and other deficiencies in linxian, a high esophageal cancer incidence area in northern China

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, α-tocopherol, β-carotene, α-carotene, and lycopene in 0.1 ml of plasma sample. The average plasma retinol levels ranged from 24 to 27 μg/dl among the population groups, with 20–35% of the individuals having levels under 20 μg/dl. Low plasma β-carotene levels averaging 8–12 μg/dl were observed among the population groups. Low plasma α-tocopherol levels with average values around 700 μg/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 α-tocopherol were significantly increased. The plasma α-carotene and β-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 μg/dl were observed, and about 23% of the individuals had values under 200 μg/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.