Several postmenopausal women are
looking to choices to hormone therapy, specially in alight of the late Women's
Health initiatory research findings interesting the risks of blended estrogen
and progestogen therapy. Of especial concern are phytoestrogens, which accept
been acquiring fame ascribable their "natural" position, averred
health takes, and accessibility in a blanket array of foods and supplements.
What are Phytoestrogens?
Phytoestrogens are course happening
plant combines that have about laws of similarity to oestradiol, the most
powerful naturally coming about estrogen. All the same, phytoestrogens tend to
have feebler brings about than most estrogens, are not hived away in the body,
and can be easily broken up and obviated.
Experimental analyses have found a
glower preponderance of breast cancer, heart condition and articulatio coxae
fracture rates one of people sleeping in places like Southeast Asia, wherever
diets are generally high in phytoestrogens. In North America, cognition of
these accounted health effects has hastened capital interest in the health
welfares of phytoestrogens. Agreeing to the Food and dose establishment, the
cut-rate sale of soy foods, a major beginning of phytoestrogens, has added to
dramatically in the past times decade.
Dietary authors of Phytoestrogens
Phytoestrogens consist of to a higher
degree 20 combines and may be found in to a higher degree 300 plants, such as
herbs, grains and fruits. The three independent families of dietetic
phytoestrogens are isoflavones, lignans and coumestans:
1. Isoflavones (genistein, daidzein,
glycitein and equol) are primarily found in soy beans and soy products,
chickpeas and other legumes.
2. Lignans (enterolactone and
enterodiol) are found in seeds (primarily flaxseed), cereal bran, legumes, and
alcohol (beer and bourbon).
3. Coumestans (coumestrol) can be
found in alfalfa and clover. Most food sources containing these compounds
typically include more than one class of phytoestrogens.
The Skeletal Effects of Phytoestrogens
Much of the evidence concerning the
potential role of phytoestrogens in bone health is based on animal studies. In
fact, soybean protein, soy isoflavones, genistein, daidzein and coumestrol have
all been shown to have a protective effect on bone in animals who had their
ovaries surgically removed.
In humans, however, the evidence is
conflicting. Compared to Caucasian populations, documented hip fracture rates
are lower in countries such as Hong Kong, China and Japan where dietary phytoestrogen
intakes are high. Yet reports suggest that Japanese women have a greater risk
of sustaining a vertebral fracture than Caucasian women.
Several studies have explored the
effects of soy isoflavones on bone health, but results have been mixed, ranging
from a modest impact to no effect. Most of these studies have serious
limitations, including their short duration and small sample size, making it
difficult to fully evaluate the impact of these compounds on bone health.
Ipriflavone Supplements
Ipriflavone, a synthetic isoflavone,
has shown some promise in its ability to conserve bone in postmenopausal women.
Ipriflavone has also been shown to have a protective effect on bone density in
pre-menopausal women taking gonadotropin-releasing hormone (GnRH), a treatment
for endometriosis that triggers bone loss.
However, a definitive three-year study
of more than 400 postmenopausal women concluded that ipriflavone did not
prevent bone loss. Additionally, the compound was linked to lymphocytopenia (a
reduction in lymphocytes) in a significant number of study participants.
Lymphocytes are a type of white blood cell that helps the body fight infection.
Risks and Benefits Are Unclear
Some studies suggest that, unlike
estrogen, phytoestrogens do not appear to target breast or uterine tissue. This
suggests that they may act more like SERMS (selective estrogen receptor
modulators such as raloxifene and tamoxifen) than actual estrogens. However, in
other studies high isoflavone levels have been linked to an increased risk of
breast cancer.
Clearly, additional research is needed
to further evaluate the effects of phytoestrogens before judgments regarding
their safety and usefulness can be made.
Key Points
Based on information available at this
time, it is reasonable to make the following conclusions concerning
phytoestrogens and bone health in postmenopausal women:
1. Moderate amounts of foods
containing phytoestrogens can be safely included in the diet but do not expect
it to help build bone. Keep to the basic rule - eat the least processed forms.
2. Due to a lack of evidence and
concerns about safety, supplementation with synthetic isoflavones (ipriflavone)
is in question.
3. Postmenopausal women are encouraged
to view evidence concerning phytoestrogens and bone health as conflicting and
incomplete. For women who are estrogen dominant increasing their phytoestrogen
intake may not improve their bone position.
