Nightly fasting reduces breast cancer risk

Posted on Tue, 26 Apr 16

Eating earlier and fasting for longer in the evening significantly reduce risk of breast cancer recurrence, according to the first human study to examine the association between nightly fasting and cancer development.

Animal studies have previously found that intermittent fasting can reduce cancer related risk factors and tumor development, including breast cancers (1). One likely mechanism by which fasting reduces cancer risk is improved glucose regulation, with previous reports showing longer evening fasting is associated with better glucose regulation (lower hemoglobin A1c) and in survivors of early-stage breast cancer a higher hemoglobin A1c (HBA1c) of 7.0% or more has been associated with a 30% increase in risk of breast cancer recurrence (2,3). 

To see if longer nightly fasting predicted recurrence and mortality, data was collected from 2413 women with early–stage breast cancer and compared to nightly fasting duration (4). It was found that fasting fewer than 13 hours per night was associated with a 36% higher hazard for breast cancer recurrence when compared with fasting 13 or more hours per night. It was also found that nightly fasting duration was associated with longer sleep and significantly lower HBA1c levels. 

“Prolonging the length of the nightly fasting interval may be a simple, non-pharmacologic strategy for reducing the risk of breast cancer recurrence,” concluded the study investigators. “Improvements in glucoregulation and sleep may be mechanisms linking nightly fasting with breast cancer prognosis.”

References: 

1. Rogozina OP, Nkhata KJ, Nagle EJ, et al. The protective effect of intermittent calorie restriction on mammary tumorigenesis is not compromised by consumption of a high fat diet during refeeding. Breast Cancer Res Treat. 2013 Apr;138(2):395-406.
2. Marinac CR, Natarajan L, Sears DD, et al. Prolonged Nightly Fasting and Breast Cancer Risk: Findings from NHANES (2009-2010). Cancer Epidemiol Biomarkers Prev. 2015 May;24(5):783-9.
3. Erickson K, Patterson RE, Flatt SW, et al. Clinically defined type 2 diabetes mellitus and prognosis in early-stage breast cancer. J Clin Oncol. 2011 Jan 1;29(1):54-60.
4. Marinac CR, Nelson SH, Breen CI, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016 Mar 31.