Will a Mediterranean diet (BC-Med) affect biomarkers of health in breast cancer survivors?

Abstract

Background: The number of breast cancer survivors is increasing owing to improved screening, detection and more targeted treatments. In fact, 5-year breast cancer survival rates in New Zealand have significantly improved by 2.9% over the past decade. Despite these encouraging survival rates, women previously diagnosed with breast cancer tend to be at increased risk of recurrence, co-morbidity and mortality. Weight at diagnosis and consequent weight gain are commonly reported findings in breast cancer research. Dietary and lifestyle interventions aimed at attenuating the risk of weight gain and obesity could be appropriate for reducing the subsequent risk of poor prognosis and associated chronic diseases. Following breast cancer diagnosis women are likely to be motivated to make lifestyle and dietary changes and the role of diet in improving breast cancer health biomarkers and prognosis is beginning to be explored, with current recommendations advocating a Low-fat diet. The Mediterranean diet has been shown to generate beneficial effects on human health and chronic disease, even in populations outside of the Mediterranean. Aim: The aim of the research was to investigate whether a Mediterranean diet (BCMed) improved the biomarkers of health in breast cancer survivors through designing and implementing an education package to support the use of the BC-Med. Methods: Data were derived from a randomised control trial of post-menopausal women, previously diagnosed with stage 1 - 3 breast cancer. The trial consisted of three dietary arms: the BC-Med and the Low-fat arms that received intensive dietary and lifestyle education, and the control arm that received no support. Outcome measures for weight, body mass index (BMI), waist circumference, blood lipids, blood glucose, dietary adherence, and quality of life were measured before and after a 6- month nutrition education intervention. A 3-day food diary and questionnaires assessed dietary intakes. Results: Both dietary intervention arms on average lost weight over the course of the intervention, with significant (p < 0.05) decreases seen in BMI and waist circumference measurements, and more marked changes observed in the BC-Med arm (-1.61 ± 4.43kg, -1.02 ± 2.00kg/m2 and -1.40 ± 3.88cm respectively). The control arm gained weight and significantly (p < 0.05) increased BMI and waist circumference measurements overall (1.10 ± 3.03kg, 0.40 ± 1.65kg/m2 and 1.94 ± 2.94cm respectively). Positive trends in blood biomarkers were observed for the intervention arms. Dietary adherence was deemed sufficient also. Conclusion: Nutritional education and group support appears to exert beneficial effects on health biomarkers in breast cancer survivors and of lesser importance is the type of diet that forms the basis of the education.