Dairy products and their key nutrients as protective factors against colorectal cancer risk: The Multiethnic Cohort.

Previous research suggests that dairy consumption may reduce colorectal cancer (CRC) risk, potentially due to key nutrients found in dairy products. However, most of these studies were performed in mainly White populations, limiting our understanding of dairy and CRC risk in other races and ethnicities. We examined associations between dairy intake and CRC risk in 192,644 participants across five racial and ethnic groups from the Multiethnic Cohort (MEC) Study. Dietary intake was assessed using a validated food frequency questionnaire, and Cox proportional hazards models were used to estimate the associations of dairy products, milk, lactose, calcium, and vitamin D with CRC risk. Analyses were further stratified by race and ethnicity, sex, and tumor subsite. Over an average follow-up of 20 years, 5743 CRC cases were identified. Higher intakes of total dairy products (hazard ratios HRQ5vsQ1 = 0.85, 95% confidence interval CI 0.77-0.93, ptrend = .001) and milk (HRQ5vsQ1 = 0.82, 95% CI 0.75-0.90, ptrend Q5vsQ1 = 0.80, 95% CI 0.71-0.91, ptrend = .001), vitamin D (HRQ5vsQ1 = 0.87, 95% CI 0.75-1.02, ptrend = .258), and lactose (HRQ5vsQ1 = 0.85, 95% CI 0.77-0.93, ptrend = .001) also showed inverse associations with CRC. Stratified analyses revealed stronger benefits from dairy and milk consumption among Latino participants. Tumor site analyses indicated notably stronger protection against cancers in the colon, particularly the left colon. Our findings support a protective role of dairy products and their key nutrients against CRC across diverse racial and ethnic populations. These results underscore the potential importance of dairy consumption in CRC prevention and call for further research into the biological mechanisms underlying these associations.