Dietary Intervention to Increase Fruit and Vegetable Consumption in Breastfeeding Women: A Pilot Randomized Trial Measuring Inflammatory Markers in Breast Milk

Background: Diets rich in fruits and vegetables (F/V) can reduce the inflammatory profile of circulating cytokines and potentially decrease the risk of breast cancer. However, the extent to which a diet rich in F/V alters cytokine levels in breast tissue remains largely unknown. Breast milk provides a means of assessing concentrations of secreted cytokines in the breast microenvironment and is a potential tool for studying the effects of diet on inflammation in breast tissue and breast cancer risk.

Objective: The aim of this pilot randomized trial was to test the feasibility of increasing F/V intake in breastfeeding women and of measuring changes in markers of inflammation in breast milk.

Design and intervention: Participants randomized to the intervention (n=5) were provided weekly boxes of F/V, along with dietary counseling, to increase consumption of F/V to 8 to 10 daily servings for 12 consecutive weeks. Controls (n=5) were directed to the US Department of Agriculture's "ChooseMyPlate" diet for pregnancy and breastfeeding.

Participants/setting: Ten breastfeeding women consuming fewer than five servings of F/V per day, as estimated by the National Institutes of Health "All-Day" Fruit and Vegetable Screener (F/V Screener), were recruited through flyers and a lactation consultant between February and May 2016 in the Western Massachusetts area.

Main outcome measures: Baseline demographic and F/V intake data were collected during enrollment. At week 1 and week 13 (final) home visits, participants provided milk samples and anthropometric measurements were recorded. Participants completed F/V screeners at baseline and at study end. Adiponectin, leptin, C-reactive protein, and 11 additional cytokines were measured in breast milk collected at weeks 1 and 13.

Statistical analyses: F/V consumption at baseline and after the final visit, and between controls and intervention groups, was compared with dependent and independent t tests, respectively. Differences between cytokine levels at weeks 1 and 13 were assessed with a mixed-effects repeated-measures model.

Results: All women in the intervention increased F/V intake and were consuming more servings than controls by week 13; daily serving of F/V at baseline and final visit: controls=1.6 and 2.0, diet=2.6 and 9.9. Most cytokines were detected in the majority of milk samples: 12 were detected in 90% to 100% of samples, one was detected in 75% of samples, and one was detected in 7.5% of samples; coefficients of variation were below 14% for 11 of the cytokines.

Conclusions: These preliminary findings indicate that it is feasible to significantly increase F/V intake in breastfeeding women and provide support for conducting a larger diet intervention study in breastfeeding women, in which longer-term benefits of the intervention are assessed.