Prolonged overnight fasting may reduce breast cancer risk

Issue: May 25, 2015

PHILADELPHIA — Prolonged nighttime fasting may reduce glycemic markers that are associated with an increased risk for breast cancer, according to study results presented at the American Association for Cancer Research Annual Meeting.

“This is one of the first studies to show a link between prolonged nightly fasting and breast cancer risk in a nationally representative sample of women,” Ruth E. Patterson, PhD, study researcher, professor of family medicine and public health and leader of the Cancer Prevention Program at the Moores UCSD Cancer Center, told HemOnc Today. “Several small, laboratory-based studies of intermittent fasting suggest that this dietary pattern positively influences glucoregulatory function in humans, which would putatively reduce breast cancer risk. In addition, research has shown that women who work the night shift — which implies late-night eating — are at greater risk of developing breast cancer.”

Patterson and colleagues evaluated dietary, anthropometric and glycosylated hemoglobin (HbA1c) data from 2,212 women and 2-hour postprandial glucose concentrations from 1,066 women from the 2009 to 2010 U.S. National Health and Nutrition Examination Survey. The mean age of the population was 46.8 years (standard error [SE] = 0.66).

Researchers calculated nighttime fasting duration using time-stamped 24-hour food records. They evaluated separate linear regression models that associated nighttime fasting with HbA1c and 2-hour glucose concentrations and modeled logistic regression associations of nighttime fasting duration with elevated HbA1c (HbA1c ≥ 39 mmol/mol or 5.7%) and elevated 2-hour glucose (glucose ≥ 140 mg/dL).

The average fasting interval was 12.4 hours (SE = 0.08) per night.

Overall, each 3-hour increase in nighttime fasting reduced the 2-hour postprandial glucose measurement by 4% (beta = 0.96; 95% CI, 0.93-1) and HbA1c by a 0.4 unit decrease, although the latter did not reach statistical significance (beta = –0.39; 95% CI, –0.84 to –0.05).

The logistic regression model indicated each 3-hour increase in nighttime fasting duration reduced the odds of elevated HbA1c by nearly 20% (OR = 0.81; 95% CI, 0.68-0.97). A 3-hour increase in nighttime fasting also was associated with a statically insignificant reduced odds of having elevated 2-hour glucose (OR = 0.78; 95% CI, 0.53-1.54).

“An important aspect of this dietary pattern is that it does not require nutrition education, access to healthy foods or costs involved in many other dietary recommendations,” Patterson said. “We believe that this change in the nightly fasting interval is a simple and feasible behavioral target that could lead to increased self-efficacy and stimulate people to make additional healthful lifestyle.”

Randomized trials are needed to confirm the linkage between extended overnight fasting and improved glycemic biomarkers, Patterson said.

“We have submitted a proposal to test our hypothesis by conducting a randomized, controlled trial of overweight or obese postmenopausal women whose usual nightly fasting interval is less than 12 hours,” she said. “We will continue to test this hypothesis in other study samples, as well. In particular, we plan to use data from the Women’s Health Eating and Living Study of breast cancer survivors to test whether a prolonged nightly fast can reduce the risk for breast cancer recurrence and mortality.” – by Cameron Kelsall

Reference:

Marinac CR, et al. Abstract 1234. Presented at: American Association for Cancer Research Annual Meeting; April 18-22, 2015; Philadelphia.

For more information:

Ruth E. Patterson, PhD, can be reached at Moores UCSD Cancer Center, 9500 Gilman Drive #0901, La Jolla, CA 92093; e-mail: repatterson@ucsd.edu.

Disclosure: The researchers report no relevant financial disclosures.