Virgin olive oil as a source of phytoestrogens
In their study of the dietary intake of phytoestrogens in the EPIC cohort, Zamora-Ros et al. do not indicate the contribution that will be made by virgin olive oil. It is understandable that it was difficult to include this in Table 4, as this contribution is very low or zero in non-Mediterranean countries, but it should be mentioned in the text. The mean lignan content of virgin olive oil has been estimated as 2.81 mg/100 ml, pinoresinol being the predominant lignan. In the Greek EPIC cohort, with a mean olive oil intake of 52.0 g/day for men and 44.3 g/day for women, this corresponds to a daily intake of total lignans from olive oil of approximately 1.46 mg and 1.24 mg respectively. This intake of olive oil lignans may contribute to a possible protective effect against ER+ breast cancer in postmenopausal women. It is noteworthy that although most studies of healthy dietary patterns (rich in vegetables) do not show a significant association with breast cancer, it was found that the healthy/Mediterranean pattern, which includes olive oil, was associated with a decreased risk of breast cancer. Moreover, pinoresinol was found to be an important contributor to the protective effect of lignans against postmenopausal breast cancer in the French EPIC cohort. Lignans are of particular public health interest, as they constitute the major phytoestrogen intake in western populations, and although intake of soy isoflavones is high in some countries in the EPIC study, there is no evidence that they have a protective effect against breast cancer in western populations.