Effects of soy and cruciferous vegetables on breast cancer treatment-related symptoms

This study examined improvement in treatment related menopausal symptoms in patients who have had breast cancer and eat a diet rich in soy or cruciferous vegetable. This study found that higher soy and cruciferous vegetable intake was associated with less treatment-related menopausal symptoms and fatigue.

Treatment for breast cancer can lead to side-effects months or years after the treatment has been completed.  This can be associated with endocrine (hormone) therapy. Commonly reported late effects include menopausal symptoms such as hot flashes, night sweats, tiredness or hair thinning. Certain foods, such as soy or cruciferous vegetables (such as cauliflower, cabbage, broccoli, or greens), are thought to help improve side-effects. 

It is unclear if any benefits have been seen in patients eating a soy or cruciferous vegetable rich diet. 

This study aimed to examine the association between dietary intake of soy or cruciferous vegetables and breast cancer treatment related symptoms in a Chinese-American (CA) and a Non-Hispanic White (NHW) population. This study included 192 CA and 173 NHW female breast cancer patients (stages 0-III). Patients were interviewed over the phone and via dietary questionnaires.

In the whole group, lower menopausal symptoms were noticed by women with a higher soy intake. However, this association was strongest for NHW patients. A higher cruciferous vegetable intake was linked with lower menopausal symptoms. 

This study found that higher soy and cruciferous vegetable intake was associated with less treatment-related menopausal symptoms and fatigue.

There are concerns with soy intake for breast cancer patients and the evidence in this study is not high enough to make dietary changes.