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Intake of Soy Isoflavones Reduces Breast Cancer Incidence among Women in North America
Author(s) -
JaceldoSiegl Karen,
Gatto Nicole,
Beeson Lawrence,
Fraser Gary
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.406.5
Subject(s) - medicine , breast cancer , isoflavones , confounding , incidence (geometry) , soy protein , cancer , lower risk , relative risk , proportional hazards model , confidence interval , physics , pathology , optics
Inconsistency in findings from studies on soy intake and breast cancer risk, particularly among Western populations, has given greater weight to concerns about the safety of soy consumption. We prospectively examined associations between soy consumption and breast cancer incidence by Cox proportional hazards regression, controlling for important confounders. Of 62,511 Seventh‐day Adventist women recruited, 50,288 participants remained after exclusions. Soy consumption was assessed at baseline by a quantitative FFQ. New breast cancer cases through 2011 were identified by record linkage with data from 48 state cancer registries. There were 892 new breast cancer cases during a mean follow‐up of 7.87 years. Intake of soy protein, soy isoflavones, soybeans and tofu, soymilk, and meat analogues were lower among women with breast cancer than those without cancer. Subjects in the highest soy protein intake quintile (median of 18.24 g/d) compared the lowest quintile (median of 0.13 g/d) had a 21% reduced risk of developing breast cancer (RR = 0.79, 95% CI = 0.64, 0.97; p for trend = 0.03). Women in the highest quintile of total isoflavones intake (median of 44.4 mg/d) had a 22% reduced risk of breast cancer compared to those with a median intake of 1.15 mg/d (RR = 0.78, 95% CI = 0.63, 0.97; p for trend = 0.01). For soybeans and tofu, soy milk and meat analogues, there was a suggestion that greater intake compared to the lowest quintile of intake could be protective, but the effect sizes were smaller as these represented only portions of the total soy intake. In conclusion, soy intake is associated with reduced risk of breast cancer in a largely Caucasian and African‐American population from North America.