Folate, vitamin B(6), and vitamin B(12) intake and the risk of breast cancer among Mexican women.
BACKGROUND
High intake of folate, vitamin B(6), and vitamin B(12) have been hypothesized to lower the risk for breast cancer. We conducted a population-based case-control study to evaluate the risk for breast cancer among Mexican women with relatively low vitamin intakes.


METHODS
We included 475 women (median age, 53 years; range, 23-87 years) diagnosed with incident breast cancer through six hospitals in Mexico City and interviewed them to obtain data on breast cancer risk factors and their usual diet using a food frequency questionnaire. We selected 1,391 (median age, 49 years; range, 18-82 years) controls from the Mexico City population using a national sampling frame.


RESULTS
Compared with women in the lowest quartile, the odds ratio for breast cancer for women in the highest quartile of folate intake was 0.64 [95% confidence intervals (CI), 0.45-0.90; P, test for trend = 0.009] and 0.32 (95% CI, 0.22-0.49; P, test for trend < 0.0001) for vitamin B(12) intake. Among postmenopausal women, intakes of folate and vitamin B(12) were associated with a lower risk of breast cancer and those associations were stronger than among premenopausal women. The inverse association of folate and breast cancer was stronger among women who consumed a high level of vitamin B(12) as compared with women consuming diets low in vitamin B(12). No association was observed for vitamin B(6) intake.


CONCLUSIONS
In this population, high intakes of folate and vitamin B(12) were independently associated with decreased breast cancer risk, particularly among postmenopausal women.
Instituto Nacional de Salud Publica, Av. Universidad 655, Col. Santa Maria Ahuacatitlan, Cuernavaca, Morelos 62508, Mexico.
Martin
M
Lajous
Eduardo
E
Lazcano-Ponce
Mauricio
M
Hernandez-Avila
Walter
W
Willett
Isabelle
I
Romieu
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000517:prevention & control*; D016022:Case-Control Studies; D016001:Confidence Intervals; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D008327:Mammography; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D009367:Neoplasm Staging; D016017:Odds Ratio; D017698:Postmenopause; D017697:Premenopause; D011336:Probability; D011379:Prognosis; D018570:Risk Assessment; D014805:Vitamin B 12 / Q000008:administration & dosage*; D025101:Vitamin B 6 / Q000008:administration & dosage*
D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12