Download Phytoestrogens used for the treatment of menopausal

Phytoestrogens and the
menopause
G.B.Lockwood,
School of Pharmacy &
Pharmaceutical Sciences,
University of Manchester,
Manchester, M13 9PL
Menopausal Symptoms
• Vasomotor symptoms-mainly hot flushes,
insomnia, heavy sweating, headaches, mood
swings, irritability, depression
• Vaginal dryness, soreness, loss of libido?
• Osteoporosis
• Breast cancer
• Cardiovascular disease
• Cognitive effects
Phytoestrogens
• Defined as plant constituents which bind to
estrogen receptors, ER and ER
• Major classes include;
Isoflavones, sources include soy, red clover
and Phaseolus beans
Lignans, sources include flax & grains
Stilbenes, one example is resveratrol
Coumestans, 3 and 4 methoxycoumesterol
Major phytoestrogenswidely available
• Phytoestrogens are mainly used instead of HRT
due to fears of links to breast cancer
• Bind to estrogen receptors 0.001-100% activity of
estradiol
• Soy isoflavones-50mg/day based on presumed
intake of Far Eastern populations
• Soy products- soy milk/tofu mainly glycosides,
miso/tempeh/soy sauce increasing aglycone
composition
• Red Clover isoflavones-  40mg
• Flax Lignans- c40g flaxseed (20mg/day)
• Resveratrol-15-200mg/day
Soy
Soy isoflavones
HO
HO
O
OH
O
O
OH
OH
daidzein
genistein
HO
O
O
H3CO
O
OH
glycitein
Soy for menopausal symptoms
• Hot flushes are the major clinical symptom
investigated
• Epidemiological data-10-20% incidence of hot
flushes in China/Japan, 70-80% in Western
countries
• Cause could be > Soy factor
• < 1mg soy isoflavones in Western diets, 50-200mg
in Japanese diets
• A US survey revealed 7.4% of women used soy
products for perimenopausal symptoms
• 50-60% success of placebo in trials
Soy activity
• Some phytoestrogens act as estrogen agonists,
some antagonists-Concentration dependent?
• Isoflavones have agonist effect in low estrogen
environments, antagonist effect in high estrogen
environment
• Estrogen reduced at start of menopause, hence
isoflavones have agonist effect
• Antagonist effect due to competition with
endogenous 17-estradiol
Rated success of Soy products in treating
menopausal symptoms, mainly hot flushes
Trials
included
No. +ve
No. ve
Reference
10
4
6
Huntley A. L; Ernst E. Soy for the treatment of perimenopausal symptoms-a systematic review. Maturitas (2004), 47, 1-9.
8 on soy
foods,
34-134mg/day
1
7
Krebs, E. E, Ensrud, K. E, MacDonald, R, Wilt, T. J. Phytoestrogens for
treatment of menopausal symptoms: a systematic review. Obstetrics &
Gynecology (2004), 104, 824-836.
5 on soy
extract, 50150mg/day
2
2
8
3
5
13
Overall
benefit
Kronenberg F, Fugh-Berman A. Complementary and alternative medicine
for menopausal symptoms: a review of randomized, controlled trials.
Annals of Internal Medicine (2002) , 137, 805-13.
Messina, Mark; Hughes, Claude. Efficacy of soyfoods and soybean
isoflavone supplements for alleviating menopausal symptoms is positively
related to initial hot flush frequency. Journal of Medicinal Food (2003),
6(1), 1-11.
Variability in clinical trials of soy
for menopausal symptoms
• Different products and foods contain
varying levels of isoflavones
• Optimum dose is not known
• Formulated products may not contain stated
levels
• Trial duration ranges from 1-4 months
• Variability and deficiencies in reporting of
outcomes
Vaginal symptoms
• No beneficial effects on genital atrophy can
be expected
• Vaginal dryness variably improved
• Little data from clinical trials
Osteoporosis
• Reduction in bone density
• Common in menopausal women
• Reduction in estrogen at menopause causes
increased osteoclastic bone resorption
• Bone loss may continue for 5-10 years after
menopause
Possible mechanism of action in
osteoporosis
• Prevention of calcium loss
• Beneficial effects on osteoblasts
• Influence on secretion of calcitonin which
suppresses bone resorption
• Genistein/daidzein suppress osteoblast
activity in relation to bone turnover
• May affect osteoblasts by mediating
cytokine production in osteoblasts
Conventional treatments for
osteoporosis
• Women have higher incidence of osteoporotic
fractures due to lower peak bone mass, and abrupt
reduction in estrogen at menopause accelerates
bone loss
• HRT-not recommended for long term treatment
• Inhibitors of bone turnover eg calcitonin,
biphosphonates
• Bone formation stimulating agents eg fluoride
Use of soy isoflavones for
osteoporosis
• Animal research consistently shows increase in bone
mineral content (BMC) or bone mineral density (BMD)
• Daidzein & genistein increase protein synthesis &
alkaline phosphatase release by osteoblast cells in vitro
• Epidemiological data show increased consumption of
fermented products show lower osteoporotic bone
fractures
• Increased osteocalcin concentrations reported
Clinical data
• Increased BMD at lumbar spine
• Reduction in excretion of bone resorption markers eg
pyridinoline
• 54mg/day genistein reduce bone mineral loss at
femoral neck and lumbar spine, as well as 1mg
oestrogen
• Lumbar spine BMD increases by 2.4% in equol
producers (45% of postmenopausal women posses
gut microflora capable of transformation of daidzein)
• Calcium/Vitamin K2 present in soy products may act
synergistically in osteoporosis
• 50% reduction of osteoporotic fractures over 4.5
years in Chinese women (24,000 subjects)
• Trials need to be 2-3 years as bone remodelling cycle
can last 80 weeks
Significance of equol
HO
• Infants and germ-free animals do not
produce it
• Antibiotics inhibit equol production
• 30-50% of population are equol
producers
equol
daidzein
• Equol is a non-steroidal estrogen
• Equol binds to ER and ER similarly to
genistein, greater than daidzein
• Glycitein is not converted to daidzein,
hence not to equol
• Equol producers not identified in trials
• S-enantiomer has affinity for ER
O
HO
O
O
OH
OH
Breast cancer
• HRT increases risk of breast cancer (1.3-2.4 times)
over 5 years
• Epidemiological evidence from Japan shows no
link between isoflavone intake and breast cancer
• In Australian women, increased urinary excretion
of equol associated with reduced risk of breast
cancer
• Early and routine consumption is most beneficial
• Soy isoflavones possibly stimulate breast cancers,
particularly postmenopausally, correlations have
been shown between oestrogenic effect, plasma
prolactin levels, and breast cancer risk
Anti-cancer activity
• Inhibition of DNA topoisomerase
• Suppression of angiogenesis
• Induction of differentiation in cancer cell
lines
• Induction of apoptosis
• Genistein is a potent estrogen agonist and
has cell growth inhibitory actions
Cardiovascular disease
• Strong epidemiological evidence supports
benefits, but diet may contribute
• Soy protein reduces total cholesterol, LDL
cholesterol and triglycerides
• A meta analysis revealed that 34 out of 38 studies
showed cholesterol reduction, but the roles of soy
protein and isoflavones is not clear
• Reduction in systolic blood pressure has been
reported
• Soy isoflavones have produced negative findings
• Combinations of soy protein and isoflavones
produce modest improvements
• 45,694 Chinese women found systolic and
diastolic BP reduced with 25g soy over 2-3 years
Cognitive function
• Probably decreases due to decreased estrogen
levels
• Increased incidence of Alzheimer’s in
postmenopausal women
• One trial reported increase in verbal memory, but
no effect in other indicators
• 60mg/daily over 12 weeks was reported to
increase memory, pattern recognition and mental
flexibility
• Significant improvements occur in males & young
women taking 100mg/day over 10 weeks
Mode
of action
of of
soy
Binding
affinity
isoflavones
phytoestrogens
for ER & ER 
• Phytoestrogens require a flavonoid with 2-4 OH
Compound
ER
groups, methylation ofER
these reduces oestrogenic
activity.
100
100
17-estradiol
• Phytoestrogens bind to the oestrogen receptor
Genistein
4 and exert a weak 87
(ER), predominantly ER
oestrogenic effect, or anti-oestrogenic
effect0.5
Daidzein
0.1
• Phytoestrogens may affect transcription of
Formononetin
<0.01
<0.01
estrogen-regulated gene products
A
<0.01
<0.01
•Biochanin
Phytoestrogens
are antioxidants
Ipriflavone
<0.01
<0.01
Soy isoflavone distribution
• Occur as glycosides, and hydrolysis, in the oral
cavity and intestine, which allows absorption
• >20 fold inter-individual variation in hydrolysis
rate
• 50mg isoflavone leads to 50-800 ng/ml in the
plasma
• Peak concentration 6-8 hours after 100mg dose
• These levels are higher than normal plasma
oestradiol levels
• Isoflavones show less serum protein binding than
oestradiol
• Effects of the food matrix likely to be important
Ipriflavone
semi-synthetic isoflavone
• Non-oestrogenic, mainly used in osteoporosis
• Metabolised to daidzein and others
• 200mg tds have been shown to produce
statistically significant increases in BMD, and
markers of bone metabolism
• Increased
calcium uptake in the duodenum
Ipriflavone
daidzein
• Some trials show no benefits
• In one trial 13% developed subclinical
lymphocytopenia
O
O
O
HO
O
O
OH
Red Clover
Red Clover
• Lower isoflavone level than soy
• 80mg isoflavone/day produced 44%
reduction in hot flushes
• Similar benefits to soy in osteoporosis
• Reduced breast cancer, prostate cancer and
ovarian cancer risks
• Insignificant effects on lipoprotein levels
Red Clover isoflavones
HO
O
HO
O
O
OH
O
OMe
formononetin
OMe
Biochanin
Red Clover isoflavone distribution
• Formononetin and biochanin A are efficiently
demethylated to daidzein and genistein
respectively
• Peak concentrations of daidzein and genistein are
12 and 2 hours after a 40 mg dose of isoflavones
• Formononetin is also converted to equol via
demethylation to daidzein
• Levels reported are c10% of those reported for
equivalent doses of soy isoflavones
HO
O
HO
O
OH
O
O
OMe
OMe
Biochanin
formononetin
HO
HO
O
O
O
OH
O
OH
daidzein
OH
genistein
Flaxseed
Flaxseed
• 40g flaxseed is as effective as HRT for mild
menopausal symptoms (25g ineffective)
• 25g Flax has a greater effect on estrogen
metabolism than the same dose of soy
• Urinary enterolactone positively correlated with
BMD in Korean postmenopausal women
• Urinary enterolactone was higher in Dutch women
with greatest bone loss
• Variable results in work on flaxseed
supplementation on biochemical markers of bone
metabolism
Flax lignans
Flaxseed
• Reduction in LDL/HDL cholesterol levels
• n-3-PUFAs, particularly -linolenic acid, in
flax may have activity
• 1.5g flax lignan/day gives a higher
probability of intact cognitive function
• Increased vascular compliance and
induction of synaptogenesis in the
hippocampus may be responsible
Flaxseed lignan metabolism
• The importance of the metabolites,
enterolactone and enterodiol have yet to be
elucidated
• No pharmacokinetic data available
Trans-Resveratrol
HO
OH
HO
Trans-resveratrol
trans-Resveratrol
• Physiological levels obtained from wine, up to
15mg/L
• 10-200mg dosage forms available, no specified
dosage
• Antioxidant
• Anticancer activity
• Cardioprotective
• Oestrogenic- binds to ER and ER receptors
1:7000 activity of estradiol
• Increases in bone density in postmenopausal
women have been reported
Quality
• Soy isoflavones-10/15 failed, levels 30-99%
• 300% variability between different soy food
product types ie raw, soaked, cooked, drink, tofu
• Soy infant formulas-up to 25% variability
• Soy milk-70% variability
• Tofu-50% variability
• Phytoestrogens-28/32 failed, levels 0% and 383%,
all products claiming genistein/daidxein failed
• Red clover-Promensil passed
• A number of products do not state levels of named
constituents
• No data on flax lignans or resveratrol
Adverse effects
• Soy-gastrointestinal problems, supplement
unpalatability (particularly soy drinks), nausea,
allergy in one trial
• In vitro genotoxicity with isoflavones
• High level male tofu consumers suffered poor
cognitive performance, lower brain weight!
• High intake in animal studies suggests they may
affect fertility
• Adverse effects of HRT not reported in any of the
trials (breast tenderness, vaginal bleeding)
• Vaginal spotting
• No reported adverse effects-Red clover/Flax
Conclusions
• Soy, red clover, and flax are the main sources of
dietary estrogens
• Phytoestrogens may have oestrogenic or antioestrogenic activity depending on circulating
levels of sex hormones, and may stimulate breast
cancer
• Generally safe-much epidemiological evidence
• Other components may interfere with
activity/bioavailability