Calcium supplements and colorectal adenomas. Polyp Prevention Study Group

Area of Science:

• Gastroenterology
• Oncology
• Nutritional Science

Background:

• Observational studies suggest calcium intake may prevent colorectal neoplasia.
• Colorectal adenomas are precursors to most colorectal cancers.

Purpose of the Study:

• To investigate the hypothesis that calcium supplementation protects against colorectal adenoma recurrence.
• To quantify the effect of calcium carbonate on adenoma recurrence in a randomized trial.

Main Methods:

• A randomized, double-blind trial involving 930 patients with a history of colorectal adenomas.
• Participants received daily calcium carbonate (3 gm; 1200 mg elemental calcium) or placebo.
• Follow-up colonoscopies were conducted at one and four years, with analysis focused on adenoma recurrence.

Main Results:

• Calcium supplementation was associated with a reduced risk of recurrent adenomas.
• The adjusted risk ratio for one or more adenomas was 0.81 (95% CI 0.67 to 0.99).
• The adjusted ratio for the average number of adenomas was 0.76 (95% CI 0.60 to 0.96).

Conclusions:

• Calcium supplementation demonstrates a modest protective effect against colorectal adenomas.
• The effect appears independent of baseline dietary factors.
• No adverse toxicity was observed with calcium supplementation.