Riboflavin, vitamin A and zinc status in Chinese subjects in a high-risk area for oesophageal cancer in China.

1. An endoscopic survey was done in Linxian, Henan Province, Northern China on 527 people in May 1980 and histological evidence of oesophageal lesions was obtained. 2. Blood samples were collected from 58 men and 53 women aged 22-71 yr. Measurements of riboflavin, vitamin A and zinc status were made. 3. Most (97 per cent) had biochemical ariboflavinosis on the basis of erythrocyte glutathione reductase activation coefficients equal to or greater than 1.30. Five per cent of subjects had deficient vitamin A status (plasma retinol less than 10 micrograms/dl and one of these subjects reported night blindness) and 37 per cent had low vitamin A status (10-20 micrograms/dl). Approximately 24 per cent of the Chinese had low plasma zinc by comparison with values for subjects in Denver. Plasma retinol binding protein concentration was also low but was only measured in 56 subjects. 4. Concentrations of plasma carotene were relatively high and only one person had a value less than 20 micrograms/dl. The value of plasma carotene as a measure of vitamin A status in this community is discussed. 5. There was no difference between the sexes for any of the measurements made. In addition there was no difference in the biochemical measurements between those with and without oesophageal lesions (oesophagitis 66 per cent, clear cell acanthosis (CCA) 88 per cent) or those with intermittent dysphagia (26 per cent). 6. Multiple linear regression showed no relationship between the biochemical data and either oesophagitis or CCA. There were, however, inverse relationships between oesophagitis and CCA in both sexes and in addition, plasma carotene and riboflavin status tended to fall while plasma retinol tended to increase with age. 7. The role which these nutritional deficiencies may play in facilitating neoplastic processes is discussed.