Prospective cohort studies of vitamin B-6 intake and colorectal cancer incidence: modification by time?
American Journal of Clinical Nutrition, 08/20/2012
Zhang X et al. – This data do not support a strong role of adulthood vitamin B–6 intake in colorectal carcinogenesis in these US health professionals.
Methods- Authors assessed vitamin B–6 intake every 4 y by using validated food–frequency questionnaires and followed 86,440 women and 44,410 men for ≤28 y.
- Cox proportional hazards regression was used to estimate multivariable RRs and 95% CIs.
- The total vitamin B–6 intake was significantly associated with an 20–30% lower risk of colorectal cancer in age–adjusted results, but this association became attenuated and nonsignificant after additional adjustment for nondietary and dietary factors.
- When the highest to lowest quintiles of cumulative total vitamin B–6 intake were compared, RRs (95% CIs) for colorectal cancer were 0.99 (0.80, 1.24; P–trend = 0.55) for women and 0.95 (0.73, 1.23; P–trend = 0.75) for men.
- For the same comparison, RRs were 0.92 (0.73, 1.16) for total vitamin B–6 intake 0–4 y before diagnosis, 0.99 (0.78, 1.26) for intake 4–8 y before diagnosis, 0.92 (0.71, 1.21) for intake 8–12 y before diagnosis, and 0.93 (0.69, 1.26) for intake 12–16 y before diagnosis in women.
- Corresponding RRs for men were 0.86 (0.63, 1.17), 0.96 (0.70, 1.32), 0.90 (0.63, 1.29), and 1.16 (0.75, 1.79).
- Results did not differ by cancer subsite, source of vitamin B–6 (food or supplement), alcohol consumption, or folate intake.
