Braakhuis A, Campion P, Bishop K. The effects of dietary nutrition education on weight and health biomarkers in breast cancer survivors. Med Sci (Basel). 2017;5(2):12.
To determine the effects of dietary changes on weight, waist circumference, BMI, blood lipid profiles, and glucose profiles in breast cancer survivors
Six-month, 3-arm, parallel randomized control trial with baseline testing and post-intervention testing
Fifty postmenopausal women aged ≥50 years from Auckland, New Zealand, previously diagnosed and treated for stage 1, 2, or 3 breast cancer; all women included in the study had a BMI >25 and had completed treatment (chemotherapy and surgery) at least 3 months and less than 3 years (including hormone therapy) prior to study start. Participants were excluded if they were on anti-inflammatory medications, drank more than 2 alcoholic beverages per day, smoked tobacco, or had poorly controlled diabetes mellitus. Women of any ethnicity were eligible to participate.
Participants were randomly assigned to 1 of 3 arms:
Arm 1: Mediterranean diet
Arm 2: Healthy, low-fat diet
Arm 3: No treatment (control)
Arms 1 and 2 received 6 group nutrition and lifestyle education sessions once a month with 6 summary newsletters.
Study Parameters Assessed
Body weight, BMI, waist circumference, complete lipid profile, hemoglobin A1c (HbA1c), adherence to Mediterranean eating pattern (using PREDIMED questionnaire), quality of life score (functional assessment of cancer therapy-breast [FACT-B] questionnaire), group education attendance, and 3-day food diary (completed once during intervention period)
Primary Outcome Measures
Change in body weight, BMI, and waist circumference
Participants who followed the Mediterranean Diet had significantly greater weight loss (-1.61 kg), decreased BMI (-1.02), and reduced waist circumference (-1.40 cm). These parameters were also improved in the group who followed a low-fat diet, but to a lesser extent (-1.35 kg weight loss, -0.56 BMI, -1.31 cm waist circumference). The control arm gained weight (+1.10 kg) and had an increase in BMI (+0.58) and waist circumference (+1.94).
Obesity and overweight status are associated with an increased risk of developing breast cancer1 and poorer prognosis for breast cancer survivors.2 Mechanisms related to obesity that are thought to influence the progression of breast cancer include increased levels of circulating insulin and insulin-like growth factor, sex hormones, and cytokines released from adipose tissue.3 In this study and in others,4 breast cancer survivors tend to gain weight during and after cancer treatment. Targeted treatment strategies such as improved diet and physical exercise benefit our patients directly, by improving markers related to cancer progression, and indirectly, by decreasing weight.
This study compared 2 dietary interventions to a control no-treatment arm and found marked improvement in weight, BMI, and waist circumference in the Mediterranean diet arm, and some improvement in the healthy low-fat arm. Other studies have observed a similar trend of improved weight loss and waist circumference with the Mediterranean diet vs low-fat diet,5,6 but the Mediterranean diet is more than just an effective diet for weight loss in this population.
The Mediterranean diet is a great option for breast cancer survivors. It focuses on vegetables, fruits, legumes, whole grains, fish, and extra virgin olive oil (EVOO), ingredients that we know are important for their health. Furthermore, it is a colorful diet, rich in phytochemicals that include antioxidants, anti-inflammatories, and polyphenols. The Mediterranean diet has been shown to decrease markers related to metabolic syndrome (high-sensitivity C-reactive protein [hs-CRP], interleukin [IL]-7, IL-18, and insulin resistance),7 which is associated with increased cancer incidence and cancer-related mortality, and markers related to inflammation8 and lipid oxidation.9 It has also been shown to decrease incidence of breast cancer10 and decrease breast cancer recurrence.11
What is the take-home message? Breast cancer survivors need your help to maintain or lose weight after cancer treatment. Without any intervention, a trend toward weight gain has been observed, which worsens their prognosis. Choosing a diet rich in phytochemicals gives them additional benefit through various mechanisms, and the Mediterranean diet is a well-documented good option. Dietary counseling was found to be effective in this study; however, other studies have found improved compliance when patients had hands-on experience such as cooking classes.12 Unrelated to this study, let us not forget the additional importance of physical exercise for weight loss and breast cancer survivorship!