Glucosamine and Chondroitin Supplements and Risk of Colorectal Adenoma and Serrated Polyp

Background: Studies have shown an inverse association between use of glucosamine and chondroitin supplements and colorectal cancer risk. However, the association with the precursor lesion, colorectal adenoma and serrated polyp, has not been examined.

Methods: Analyses include 43,163 persons from the Nurses' Health Study (NHS), Health Professionals Follow-up Study (HPFS), and NHS2 who reported on glucosamine/chondroitin use in 2002 and who subsequently underwent ≥1 lower gastrointestinal endoscopy. By 2012, 5,715 conventional (2,016 high-risk) adenomas were detected, as were 4,954 serrated polyps. Multivariable logistic regression for clustered data was used to calculate OR and 95% confidence intervals (CI).

Results: Glucosamine/chondroitin use was inversely associated with high risk and any conventional adenoma in NHS and HPFS: in the pooled multivariable-adjusted model, glucosamine + chondroitin use at baseline was associated with a 26% (OR = 0.74; 95% CI, 0.60–0.90; P_{heterogeneity} = 0.23) and a 10% (OR = 0.90; 95% CI, 0.81–0.99; P_{heterogeneity} = 0.36) lower risk of high-risk adenoma and overall conventional adenoma, respectively. However, no association was observed in NHS2, a study of younger women (high-risk adenoma: OR = 1.09; 95% CI, 0.82–1.45; overall conventional adenoma: OR = 1.00; 95% CI, 0.86–1.17), and effect estimates pooled across all three studies were not significant (high-risk: OR = 0.83; 95% CI, 0.63–1.10; P_{heterogeneity} = 0.03; overall conventional adenoma: OR = 0.93; 95% CI, 0.85–1.02; P_{heterogeneity} = 0.31). No associations were observed for serrated polyps.

Conclusions: Glucosamine/chondroitin use was associated with lower risks of high-risk and overall conventional adenoma in older adults; however, this association did not hold in younger women, or for serrated polyps.

Impact: Our study suggests that glucosamine and chondroitin may act on early colorectal carcinogenesis in older adults.