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Higher diet‐dependent acid load is associated with risk of breast cancer: Findings from the sister study
Author(s) -
Park YongMoon Mark,
Steck Susan E.,
Fung Teresa T.,
Merchant Anwar T.,
Elizabeth Hodgson M.,
Keller Jean A.,
Sandler Dale P.
Publication year - 2018
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.31889
Subject(s) - quartile , breast cancer , medicine , proportional hazards model , risk factor , cancer , estrogen receptor , endocrinology , oncology , physiology , confidence interval
Dietary factors that contribute to chronic low‐grade metabolic acidosis have been linked to breast cancer risk, but to date no epidemiologic study has examined diet‐dependent acid load and breast cancer. We used data from 43,570 Sister Study participants who completed a validated food frequency questionnaire at enrollment (2003–2009) and satisfied eligibility criteria. The Potential Renal Acid Load (PRAL) score was used to estimate diet‐dependent acid load. Higher scores reflect greater consumption of protein and phosphorus, and lower consumption of potassium, calcium and magnesium. The association between PRAL and breast cancer was evaluated using multivariable Cox proportional hazards regression. We identified 1,614 invasive breast cancers diagnosed at least 1 year after enrollment (mean follow‐up, 7.6 years). The highest PRAL quartile, reflecting greater acid‐forming potential, was associated with increased risk of breast cancer (HR highest vs . lowest quartile : 1.21 [95% CI, 1.04–1.41], p trend = 0.04). The association was more pronounced for estrogen receptor (ER)‐negative (HR highest vs . lowest quartile : 1.67 [95% CI, 1.07–2.61], p trend = 0.03) and triple‐negative breast cancer (HR highest vs . lowest quartile : 2.20 [95% CI, 1.23–3.95], p trend = 0.02). Negative PRAL scores, representing consumption of alkaline diets, were associated with decreased risk of ER‐negative and triple‐negative breast cancer, compared to a PRAL score of 0 representing neutral pH. Higher diet‐dependent acid load may be a risk factor for breast cancer while alkaline diets may be protective. Since PRAL scores are positively correlated with meat consumption and negatively correlated with fruit and vegetable intake, results also suggest that diets high in fruits and vegetables and low in meat may be protective against hormone receptor negative breast cancer.