Black Cohosh - Non-Timber Forest Products

Early research on the physiological actions of black cohosh debated
the presence of compounds that could bind to estrogen receptors and,
thus, reduce symptoms caused by the loss of estrogen production during
menopause. Several studies claimed that black cohosh had an estrogenlike
effect (Eagon and others 1997, 1999). However, a few studies on
ovariectomized rats did not detect the appropriate physical and physiological
changes (e.g., increase in uterine weight and changes in vaginal cytology)
associated with estrogen and concluded that black cohosh did not have a
hormonal effect (Einer-Jensen and others 1996, Knüvener and others 2000,
Liske and others 1998). Jarry and Harnischfeger (1985), Jarry and others
(1985), and Düker and others (1991) found that black cohosh reduced surges
in the secretion of luteinizing hormone (LH) associated with hot flashes and
sweating. Though the exact mechanism of action was not identified, it was
believed that several constituents acted simultaneously in different ways to
produce an overall estrogenic effect. Wade and others (1999) suggested that
black cohosh had both estrogen-agonistic and estrogen-antagonistic effects
on various target organs, indicating tissue selectivity. Contradictions in early
clinical studies were most likely caused by variations in the dosage, duration
of the study, number of participants, and lack of a standardized extract
that was free of contaminants (Borrelli and Ernst 2002, Borrelli and others
2003). Most current research uses standardized commercial preparations
Remifemin ® or Klimadynon ® /Menofem ® (CR BNO extract 1055).
Contradicting estrogenic or antiestrogenic actions were also clarified by
the discovery of two different types of estrogen receptors (ERs): ER-α
and ER-β. Whereas ER-αs are primarily found in the reproductive organs,
ER-βs are found in the skeletal and central nervous systems (Seidlová-
Wuttke and Wuttke 2000). Researchers are investigating the possibility
that constituents in the rhizomes act as selective ER modulators. Clinical
research indicates that black cohosh may reduce hot flashes and sweating
by reducing the secretion of LH from the hypothalamus/pituitary system in
the brain through either mixed competitive binding to serotonin receptors
(Burdette and others 2003, Seidlová-Wuttke and Wuttke 2000, Seidlová-
Wuttke and others 2003, Wuttke and others 2003) or unidentified ERs (Jarry
and others 2003), or through dopaminergic/antidepressant activity (Löhning
and Winterhoff 2000, Winterhoff and others 2003). Black cohosh has also
been associated with a significant reduction in the bone loss that leads to
osteoporosis (Nisslein and Freudenstein 2000; Seidlová-Wuttke and others
2000; Wuttke and others 2000, 2003).
The growing awareness of contraindications for HRT for individuals
with estrogen-positive breast cancer has also raised concerns about the
potential negative effects of phytoestrogens (plant chemicals that act like
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