Schisandra chinensis, commonly known as the five-flavor berry, is a plant with a long history of use in traditional Chinese medicine. It is classified as an adaptogen, a natural substance thought to help the body maintain balance and resist various stressors. This article investigates the specific claim about its influence on estrogen, distinguishing between a change in circulating hormone levels and the compound’s activity at the cellular level.
Schisandra’s Primary Role and Key Compounds
Schisandra chinensis is traditionally prized for its broad effects on systemic wellness, particularly for its ability to support liver function and enhance physical endurance. The herb’s status as an adaptogen means it is believed to exert a normalizing influence on the body, improving resistance to stress and fatigue without causing overstimulation. This property is often linked to its support of the adrenal system, which is involved in the body’s stress response.
The biological activities of the berry are primarily attributed to a group of unique compounds called lignans. These lignans, which include chemicals such as schisandrin, schisandrol, and schisantherin, are concentrated in the seeds and fruit. These dibenzocyclooctadiene lignans are considered the main source of the herb’s properties, including its protective effects on the liver and its interaction with the endocrine system.
Understanding Phytoestrogens and Estrogenic Activity
To understand Schisandra’s effect, it is necessary to first define phytoestrogens, which are plant-derived compounds with a chemical structure similar to the body’s natural estrogen. Phytoestrogens do not increase the amount of the hormone estrogen circulating in the bloodstream; instead, they exert their effects by binding directly to estrogen receptors (ERs) on the surface or inside cells. The human body has two main types of estrogen receptors, known as estrogen receptor alpha (ER-alpha) and estrogen receptor beta (ER-beta).
The binding activity of a compound is described as its estrogenic activity. ER-alpha receptors are predominantly found in tissues like the uterus and mammary glands, where activation often promotes cell proliferation. Conversely, ER-beta receptors are found in tissues such as the brain, bone, and ovaries, and their activation is frequently associated with anti-proliferative or balancing effects. Many phytoestrogens, including some in Schisandra, show a higher binding affinity for ER-beta than for ER-alpha.
Direct Evidence on Schisandra and Estrogen Receptors
Scientific studies, primarily using in vitro (cell culture) and animal models, indicate that Schisandra lignans exhibit phytoestrogenic effects. These compounds function as Selective Estrogen Receptor Modulators (SERMs), meaning they can act as an estrogen agonist (activator) in some tissues and an antagonist (blocker) in others. This tissue-specific action is determined by the relative ratio of ER-alpha and ER-beta receptors in that particular tissue.
The lignan schisandrol A has been shown in cell culture studies to induce estrogenic activity through the ER-alpha pathway, leading to increased proliferation in some estrogen-receptor positive breast cancer cells. This indicates a potential stimulating effect in specific cell types. However, studies on the whole Schisandra chinensis extract suggest a more complex, modulatory role by regulating the activation of both ER-alpha and ER-beta receptors.
The overall effect is often described as balancing, particularly concerning symptoms associated with reduced estrogen levels during menopause. Research supports Schisandra’s use for relieving menopausal symptoms, such as hot flashes and sweating, a benefit likely mediated by the herb’s SERM-like activity on ER-beta. The lignans’ preference for the ER-beta receptor, which is often linked to anti-proliferative actions, suggests a gentler, modulating influence compared to the body’s own circulating estrogen.
Safety Considerations and Drug Interactions
Given the evidence of phytoestrogenic activity, individuals with hormone-sensitive conditions, such as a history of estrogen-receptor positive cancers, must exercise caution. Although some research points to a low cancer risk due to the modulating nature of the extract, the in vitro finding of ER-alpha activation warrants clear warnings. Consulting a healthcare provider is prudent to assess the risk, especially since Schisandra has not been extensively studied in human clinical trials for this specific application.
Schisandra is also known to interact with the liver’s cytochrome P450 (CYP) enzyme system, which metabolizes many prescription medications. Specifically, the lignans can inhibit or induce certain CYP enzymes, such as CYP3A4 and CYP1A2, which are involved in drug processing. This action can alter the concentration of co-administered drugs in the body, potentially increasing their effects and side effects. Furthermore, Schisandra is considered unsafe for consumption during pregnancy due to a potential risk of stimulating uterine contractions.