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Phytoestrogen Intake

Phytoestrogen Intake

Question

Dear OncoLink "Ask The Experts,"
I have been told that patients with estrogen dependent breast cancer treated with tamoxifen must avoid food high in phytoestrogen. How much phytoestrogen can a person take/day? Is there a set a reference amount?  

Answer

Katrina Claghorn, MS, RD, Registered Dietitian at the Abramson Cancer Center of the University of Pennsylvania, responds:

It is generally recommended that women taking tamoxifen restrict their intake of foods containing phytoestrogens. Limits on the amount of soy foods are most commonly suggested since they are the primary source of phytoestrogens. Unfortunately the research is very limited and no human studies have yet been conducted, so it is impossible to provide a standard restriction. Recommendations on the amount of servings of soy foods vary from no more than 2 servings a day to no more than a total of 4 servings a week.