Background: Adherence to either the Mediterranean diet, or the low- fat diet may reduce breast cancer risk and improve prognosis. Higher levels of DNA damage are considered an important contributor to breast carcinogenesis.
Aim: To identify whether a Mediterranean-style diet could be a beneficial dietary intervention to reduce DNA damage in women with breast cancer.
Method: Postmenopausal women following treatment for breast cancer, (n=40), aged 45-76, enrolled in a randomised control clinical trial for six months. Participants were randomised into three dietary groups (Mediterranean diet (BC-MED) n=15, The New Zealand low fat healthy diet (BC-LF) n=12 and control (n=13)). Three-day food diaries and blood samples were taken at baseline and six month follow-up. Dietary counselling, education and recipe books were provided in a monthly face-to-face group session to the BC-MED and BC-LF groups. Analysis of DNA-damage was assessed using a Comet assay protocol, and food diaries were analysed using Food Works 8 Professional software (Xyris Ltd, Australia).
Results: DNA damage increased among the three groups between the baseline and follow-up, however the increase was notably significant in control group. (BC-MED p=0.0551; BC-LF p=0.0853; Control p=0.0256). From the analysis of food diary data, total fat intake was lower in the BC-LF group compared with control (p=0.0297), as were monounsaturated fat(MUFA) (p=0.03) and polyunsaturated fat(PUFA) (p=0.01). There was a marked difference in sugar intake between BC-MED and Control (p=0.05). Zinc and iron intake among the BC-MED group was substantially different from the Control (p=0.021; p=0.029, respectively). Vitamin B6 and B12 intake differs greatly between BC-MED and Control (p=0.01; p=0.04, respectively). The intake of Vitamin K in the BC-LF group was significantly different compared with the Control (p=0.04). The intake of other nutrients amongst the three dietary groups did not differ significantly.
Conclusion: Breast cancer survivors provided with nutrition education and group support show no significant change with regards to DNA damage. However, the Control group showed a significant increase. Dietary factors that may be related to changes in DNA damage include MUFA, PUFA, sugar, iron, zinc and Vitamins B6, B12, K.