Nutrient intake and esophageal cancer in the Caspian littoral of Iran: a case-control study.

The purpose of this study was to investigate the possible contribution of different dietary nutrients in the development of esophageal cancer (EC) in the Caspian littoral of Iran. Forty-one cases and 145 members of their households were matched for age and gender with 40 non-blood-relative controls and 130 members of their households for their nutrient intake. A standard 24-hour dietary recall questionnaire was used to estimate the daily intake of energy, protein, P, Fe, Na, K, vitamins C and A, thiamin, riboflavin, and niacin. Dietary nutrient deficiency was defined as less than 75% of the World Health Organization human nutritional requirements, except for P, Na, and K, for which the United States Recommended Dietary Allowances were followed. The results indicate the following: (1) The mean daily intake of all nutrients, except for riboflavin, was significantly lower in cases than in control subjects (P < .05); (2) with the exception of protein, riboflavin, and phosphorus, significant correlation was observed between the pattern of nutrient intake and health status of the study subjects (P < .05); and (3) dietary deficiency of niacin and phosphorus was associated significantly with the risk of EC development among case and control households (P < .01-.001), indicating that persons living in case households with dietary deficiencies of these nutrients have more than twice the risk of developing EC tumors than those living in control households. In conclusion, apparently some nutrients, such as P and niacin, may play a role in the etiology of esophageal cancer, and the status of these nutrients may be used eventually as an epidemiologic predictive marker for EC in the Caspian littoral of Iran and perhaps other regions.