THE LINXIAN TRIALS - MORTALITY-RATES BY VITAMIN-MINERAL INTERVENTION GROUP

Two randomized nutrition intervention trials were conducted in Linxian , an area of northcentral China with some of the world's highest rates of esophageal and stomach cancer and a population with a chronically low intake of several nutrients. One trial used a factorial design tha t allowed us to assess the effects in nearly 30 000 participants of da ily supplementation with four nutrient combinations: retinol and zinc; riboflavin and niacin; vitamin C and molybdenum; and beta-carotene, a lpha-tocopherol, and selenium. The second trial provided daily multipl e vitamin-mineral supplementation;or placebo in 3318 persons with esop hageal dysplasia, a precursor to esophageal cancer. After supplements were given for 5.25 y in the general population trial, small but signi ficant reductions in total [relative risk (RR) = 0.91] and cancer (RR = 0.87) mortality were observed in subjects receiving beta-carotene, a lpha-tocopherol, and selenium but not the other nutrients. The reducti ons were greater in women than men, and in those under compared with o ver the age of 55; however, differences by sex or age were not signifi cant. After multiple vitamin and mineral supplements were given for 6 y in the smaller dysplasia trial, reductions in total (RR = 0.93) and cancer (RR = 0.96) mortality were observed but these were not signific ant. The largest reductions were for cerebrovascular disease mortality , but the effects differed by sex: a significant reduction was observe d in men (RR = 0.45) but not women (RR = 0.90). Restoring adequate int ake of certain nutrients may help to lower the risk of cancer and othe r diseases in this high-risk population.