CALCIUM AND FRUCTOSE INTAKE IN RELATION TO RISK OF PROSTATE-CANCER

Laboratory and clinical data indicate an antitumor effect of 1,25(OH)( 2) vitamin D (1,25(OH)(2)D) on prostate cancer. High calcium intake su ppresses formation of 1,25(OH)(2)D from 25(OH)D, thereby decreasing th e 1,25(OH)(2)D level. Ingestion of fructose reduces plasma phosphate t ransiently, and hypophosphatemia stimulates 1,25(OH)(2)D production. W e thus conducted a prospective study among 47,781 men of the Health Pr ofessionals Follow-Up Study free of cancer in 1986 to examine whether calcium and fructose intake influenced risk of prostate cancer. Betwee n 1986 and 1994, 1369 non-stage A1 and 423 advanced (extraprostatic) c ases of prostate cancer were diagnosed. Higher consumption of calcium was related to advanced prostate cancer [multivariate relative risk (R R), 2.97; 95% confidence interval (CI), 1.61-5.50 for intakes greater than or equal to 2000 mg/day versus <500 mg/day; P, trend, 0.002] and metastatic prostate cancer (RR, 4.57; major source of calcium, CI, 1.8 8-11.1; P, trend, <0.001). Calcium from food sources and from 1,25(OH) (2)D levels. supplements independently increased risk. High fructose i ntake was related to a lower risk of advanced prostate cancer (multiva riate RR, 0.51; CI, 0.33-0.80, for intakes >70 versus less than or equ al to 40 g/day; P, trend, 0.007). Fruit intake was inversely associate d with risk of advanced prostate cancer (RR, 0.63; 95% CI, 0.43-0.93; for >5 versus less than or equal to 1 serving per day), and this assoc iation was accounted for by fructose intake. Non-fruit sources of fruc tose similarly predicted lower risk of advanced prostate cancer. A mod erate positive association between energy-adjusted fat intake and adva nced prostate cancer was attenuated and no longer statistically signif icant when controlled for calcium and fructose. Our findings provide i ndirect evidence for a protective influence of high 1,25(OH)(2)D level s on prostate cancer and support increased fruit consumption and avoid ance of high calcium intake to reduce the risk of advanced prostate ca ncer.