Homocysteine and Alzheimer's Disease

colonoscopy. Of the 930 subjects, 832 completed both follow-up colonoscopies: 409 from the calcium group and 423 from the placebo group. At least one adenoma was diagnosed in 127 subjects receiving calcium supplement (3 1%) and in 159 subjects receiving placebo (38%). The adjusted risk ratio was 0.81 (95 % confidence internal, 0.67-0.99;p=0.04). Interestingly, it was noted that the adjusted ratio of the average number of recurrent polyps in those receiving calcium compared with placebo was 0.76 This recent study opens up an important gate toward the use of calcium in colon polyp and cancer chemoprevention. The reported positive effect, however, although statistically significant, is nevertheless rather modest. The studies by both Holt et al." and Baron et al.17 highlight the inherent difficulties in chemoprevention (which have been extensively reviewed by Lipkin and Newrnarkls) and indicate the need for long-term studies covering periods of 10-1 5 years and for recruitment of an adequate number of compliant subjects who are willing to take calcium for such a prolonged period of observation. Furthermore, it is essential to balance dietary supplementation carefully, to avoid interactions between different dietary factors, as was observed by Alberts et a1.I6 4Fo.02).