What Is The Relationship Between Mediterranean Diet & Breast Cancer?
Title: Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial
Author: Toledo et al.
Journal: Journal of the American Medical Association (JAMA)
Objective: To evaluate the effect of 2 interventions with Mediterranean diet vs the advice to follow a low-fat diet (control) on breast cancer incidence.
The mediterranean diet is a dietary pattern designed around the traditional intake of folks who live along the north coast of the mediterranean sea, namely Spain, Italy and Greece. This diet is typically high in
- olive oil
- complex carbs
- fruits and vegetables
and typically low in:
- non-fish meat sources (poultry, beef, pork, etc)
- refined sugars (candy, baked goods, etc)
Research around the mediterranean diet has found to reduce the risk of the following:
- Cholesterol (hyperlipidemia)
- Blood pressure (hypertension)
- Heart disease
- Incidence of parkinson’s, alzheimer’s
- Death from cancer or heart attack
- Lower weight and improved weight loss
And shifting gears to breast cancer, which is what this study was looking at…
- 1 in 8 women in US will develop breast cancer in their lifetime (12%)
- In 2012, from which the most recent data is available, 224,000 women were diagnosed with breast cancer and 41,000 women died from it.
- 1.7 million women were diagnosed globally in 2012
Ways to prevent or reduce the risk of breast cancer are beginning to be investigated, including the role of diet. There are a few studies that have mixed evidence linking certain diets to breast cancer risk. The mediterranean diet has gained attention because the incidence of breast cancer in greece, spain and italy has typically been lower than in northern europe or the US.
Due to the limited and conflicting evidence linking the two, the authors of this study sought to further evaluate the effects of the mediterranean diet on breast cancer risk.
The PREDIMED, a spanish study which stands for Prevención con Dieta Mediterránea, is a 1:1:1 randomized, single-blind, controlled field trial conducted at primary health care centers in Spain.
It included 4282 women age 60-80 years, from 2003-2009, at high risk of cardiovascular disease.
Average follow up was 4.8 years and 35 new cases of breast cancer were identified.
The rates of breast cancer (per 1000 person years) in the study were observed to be:
- 1.1 for the Mediterranean diet with extra-virgin olive oil group
- 1.8 for the Mediterranean diet with nuts group
- 2.9 for the control group
The hazard ratios for breast cancer risk in the mediterranean diet compared to the control showed :
- 68% reduced risk for MeDiet with EVOO (HR 0.32, 95%CI, 0.13-0.79)
- 41% reduced risk for MeDiet with Nuts (HR 0.59, 95% CI, 0.26-1.35)
The results of the study suggest that the mediterranean diet has a protective effect on the risk of breast cancer, especially a diet high in extra virgin olive oil.
This reinforced the concept that diet does play a role in breast cancer risk and that prevention is the most sensible approach to cancer.
Toledo, E., Salas-Salvadó, J., & Donat-Vargas, C. (2015). Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial. JAMA Internal Medicine, 175(11), 1752. doi:10.1001/jamainternmed.2015.4838