10.6.9 Role in Menopause and Bone Metabolism
Menopause is experienced by every elderly woman (about 50 year of age) and is
diagnosed by amenorrhea (Ghazanfarpour et al. 2016). It is associated with a cluster
of symptoms including hot flashes, night sweating, vaginal atrophy, anxiety, nervousness, and reduced libido (Cramer et al. 2012). Because of structural and
functional similarities with human estrogen (17β-estradiol), flaxseed lignans alter
hormone metabolism (Bloedon and Szapary 2004). In the treatment of menopausal
problems of women, several studies clearly indicated that flaxseed can serve as an
alternative therapy to traditional estrogen (Bloedon and Szapary 2004). Further,
among postmenopausal women, flaxseed may also reduce serum concentration of
17β-estradiol and estrone sulfate and increase prolactin levels. However, limited
studies are available in the literature. Pruthi et al. (2007) also reported that hormonal
modulation exerted beneficial effects such as decreased hot flashes and other symptoms among postmenopausal women due to weak estrogenic activity of lignans.
Hutchins et al. (2000) reported that intake of flaxseed lignan (5–10 g/day) significantly increased urinary excretion of enterodiol, enterolactone, and total lignans. In
another study on postmenopausal women, Haggans et al. (1999) reported that
consumption of flaxseed increased urinary estrogen metabolites, namely,
2-hydroxy estrogen and 2/16 α-hydroxy estrogen excretion in a linear, dosedependent manner.
Several studies have revealed that menopause is positively associated with the
reduction of bone mineral density and the incidences of fractures (Borrelli and Ernst
2010). Lignanic compounds, which are estrogen like in nature, can exert effects on
estrogen responsive tissues, including the bones. It has been observed that human
osteoclasts and osteoblasts can express estrogen receptor to which phytoestrogens
specifically bind (Mano et al. 1996; Arts et al. 1997; Setchell and Cassidy 1999). In
spite of this, in several animal and human models, the intake of flax lignans resulted
in little or no benefit to the bone (Lucas et al. 2002; Dodin et al. 2005; Cornish et al.
2009). However, Kim and Ilich (2011) reported that flaxseed intake along with
estrogen therapy provided an extra benefit to the bones in animal models.
10.7 Adverse Effects of Flaxseed
Although individuals are not allergic to flaxseed, still in certain cases, potential
problems with flax fiber and lignan components could still occur. Some flaxseed
hypersensitivity- related anaphylactic cases have been reported (Gall 2000). Since
flaxseed lignans have structural similarity with human estrogens, they may alter
hormone metabolism. Although lignans are useful in the treatment of hormonedependent cancers as well as menopausal symptoms, higher dose of lignan may lead
to some adverse effects in menstruating women, which needs further investigations.
Although in a study, flaxseed intake (10%) resulted in low birth weight and produced
268
S. Ganguly et al.
Menopause is experienced by every elderly woman (about 50 year of age) and is
diagnosed by amenorrhea (Ghazanfarpour et al. 2016). It is associated with a cluster
of symptoms including hot flashes, night sweating, vaginal atrophy, anxiety, nervousness, and reduced libido (Cramer et al. 2012). Because of structural and
functional similarities with human estrogen (17β-estradiol), flaxseed lignans alter
hormone metabolism (Bloedon and Szapary 2004). In the treatment of menopausal
problems of women, several studies clearly indicated that flaxseed can serve as an
alternative therapy to traditional estrogen (Bloedon and Szapary 2004). Further,
among postmenopausal women, flaxseed may also reduce serum concentration of
17β-estradiol and estrone sulfate and increase prolactin levels. However, limited
studies are available in the literature. Pruthi et al. (2007) also reported that hormonal
modulation exerted beneficial effects such as decreased hot flashes and other symptoms among postmenopausal women due to weak estrogenic activity of lignans.
Hutchins et al. (2000) reported that intake of flaxseed lignan (5–10 g/day) significantly increased urinary excretion of enterodiol, enterolactone, and total lignans. In
another study on postmenopausal women, Haggans et al. (1999) reported that
consumption of flaxseed increased urinary estrogen metabolites, namely,
2-hydroxy estrogen and 2/16 α-hydroxy estrogen excretion in a linear, dosedependent manner.
Several studies have revealed that menopause is positively associated with the
reduction of bone mineral density and the incidences of fractures (Borrelli and Ernst
2010). Lignanic compounds, which are estrogen like in nature, can exert effects on
estrogen responsive tissues, including the bones. It has been observed that human
osteoclasts and osteoblasts can express estrogen receptor to which phytoestrogens
specifically bind (Mano et al. 1996; Arts et al. 1997; Setchell and Cassidy 1999). In
spite of this, in several animal and human models, the intake of flax lignans resulted
in little or no benefit to the bone (Lucas et al. 2002; Dodin et al. 2005; Cornish et al.
2009). However, Kim and Ilich (2011) reported that flaxseed intake along with
estrogen therapy provided an extra benefit to the bones in animal models.
10.7 Adverse Effects of Flaxseed
Although individuals are not allergic to flaxseed, still in certain cases, potential
problems with flax fiber and lignan components could still occur. Some flaxseed
hypersensitivity- related anaphylactic cases have been reported (Gall 2000). Since
flaxseed lignans have structural similarity with human estrogens, they may alter
hormone metabolism. Although lignans are useful in the treatment of hormonedependent cancers as well as menopausal symptoms, higher dose of lignan may lead
to some adverse effects in menstruating women, which needs further investigations.
Although in a study, flaxseed intake (10%) resulted in low birth weight and produced
268
S. Ganguly et al.