Long-term use of multivitamins and risk of colorectal adenoma in women.
BACKGROUND
Use of multivitamins may reduce the risk of colorectal adenoma, but the duration of use needed is unclear.


METHODS
We prospectively examined years of multivitamin use and risk of colorectal adenoma among 43,641 women who had a first endoscopy between 1991 and 2007 in the Nurses' Health Study II. Use of multivitamins was assessed through biennial questionnaires since 1989.


RESULTS
We documented 2277 colorectal adenoma cases. Reporting multivitamin use at any time during the study period compared with never reporting its use was associated with a reduced risk of adenoma (multivariable relative risk (RR)=0.86, 95% confidence interval (CI): 0.76-0.97). There was no clear trend with duration of multivitamin use: years of use compared with never use, ≤ 4 years (RR=0.84, 95% CI: 0.74-0.96), 5-9 years (RR=0.89, 95% CI: 0.77, 1.02), 10-14 years (RR=0.86, 95% CI: 0.74, 1.01), 15-19 years (RR=0.85, 95% CI: 0.70, 1.02), and 20-26 years (RR=0.80, 95% CI: 0.64, 1.01); (P trend=0.87). The strongest associations (years of use vs never user) were for size of adenoma: large (≥ 1 cm) <4 years (RR=0.75, 95% CI: 0.58-0.96) and in alcohol users (≥ 1.4 g per day) 20-26 years (RR=0.67, 95% CI: 0.49-0.91).


CONCLUSIONS
Our findings suggest that use of multivitamins is associated with lower risk of colorectal adenoma, even with relatively short duration of use.
Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
J
J
Massa
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA.
E
E
Cho
1] Department of Biostatistics, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA [2] Division of General Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
E J
EJ
Orav
1] Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA [2] Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA [3] Department of Epidemiology, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
W C
WC
Willett
Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
K
K
Wu
1] Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA [2] Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA [3] Department of Epidemiology, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
E L
EL
Giovannucci
D000236:Adenoma / Q000453:epidemiology*; D000328:Adult; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012306:Risk; D014481:United States / Q000453:epidemiology; D014815:Vitamins / Q000008:administration & dosage*
D014815:Vitamins