Cholesterol and fat are implicated as dietary factors enhancing the risk for colon carcinogenesis. Plant sterols such as beta-sitosterol when added to diets of experimental animals treated with colon carcinogens reduce tumor yields and counteract the proliferative changes associated with carcinogenesis. The question of whether the diet of human populations at low risk for colon cancer is mirrored in their sterol composition is addressed in this study. Four study groups consisting of 18 Seventh-day Adventist (SDA) pure vegetarians, 50 SDA lacto-ovo vegetarians, 50 SDA nonvegetarians, and 50 general population nonvegetarians were selected from the greater Los Angeles basin, and 3-day composite diets were analyzed for their sterol composition. The most significant index of dietary sterol status is the ratio, beta-sitosterol + stigmasterol/cholesterol (plant sterol/cholesterol ratio). The values for the four groups ranged from 0.49 to 16.0 (general population nonvegetarians = 0.49; SDA-nonvegetarians = 0.98; SDA lacto-ovo vegetarians = 3.26; SDA pure vegetarians = 16.0). The data also show that the absolute amounts of cholesterol consumed as a factor by itself might not be as significant as its relationship to total plant sterols in the diet.