The potential of 5-hydryoxytryptophan for hot flash reduction: a hypothesis

Hormone replacement therapy (HRT) is contraindicated in women with a history of breast cancer or a high risk of breast cancer development. Recent results from large clinical trials, such as the Women's Health Initiative, have demonstrated increased risks of thromboembolic events and a moderate increased risk of breast cancer in women using conjugated estrogens and progestogens. There is a need for viable non-hormonal alternative treatments to HRT, such as nutritional and botanical therapies, in this population of women, who tend to experience more significant vasomotor symptoms. Safe and effective therapies that do not stimulate breast cell proliferation could prove extremely useful for the management of such symptoms for women in both low- and high-risk breast cancer populations. As a non-hormonal treatment, anti-depressants, such as selective serotonin reuptake inhibitors (SSRIs), have been shown to improve hot flash symptoms in women. The proposed mechanism is related to an increase in serotonin allowing for an increase in the set point of the brain's thermoregulator. In small clinical studies, the administration of tryptophan and 5-hydroxytryptophan (5HTP), the precursors of serotonin, have been shown to reduce depressive symptoms, possibly by enhancing the synthesis of serotonin. Thus, increased serotonin levels may have the ability to decrease hot flashes in a mechanism similar to that of SSRIs without the risks of breast cell stimulation. This would be particularly desirable for menopausal women with breast cancer or with risks of breast cancer. This article discusses the background information on hot flashes, SSRIs, tryptophan, and 5HTP, and possible clinical application of 5HTP for menopausal women with breast cancer risk.