Syndrome (PCOS) is surprisingly common among women today, affecting around 10%
of Caucasian women and 15-20% of African American, Hispanic women
and indigenous Australian women. It’s no
wonder then, that the effects of diet and lifestyle on PCOS are often in debate
– in fact, the rise in unhealthy lifestyles could well be linked to a similar
rise in PCOS. Soy and soy-based products
are players in this debate.
staunch proponents and passionate objectors of soy, it can be difficult to find
an answer to the controversial question – should you include soy in your food
plan, or not?
What are the potential negatives and the possible positives? Exactly how may soy affect PCOS? And should
PCOS sufferers really stop consuming soy completely?
(Note: I talk
about several hormones throughout this article. If you want to understand more
about these hormones, head to www.ConquerYourPCOSNaturally.com,
enter your details in at the top right hand side of the page and you can
download the first three chapters of my book, ‘Conquer Your PCOS Naturally’ for
free. This will explain more)
Polycystic Ovary Syndrome (PCOS)
In order to
answer these questions effectively, it is important to understand exactly what
PCOS is. There are three diagnostic
criteria for PCOS, of which you need at least two for diagnosis. Polycystic ovaries, increased androgens
levels (‘male’ hormones such as testosterone)
and irregular or absent periods. It is
worth noting that only around half of the women with polycystic ovaries (PCO) will
suffer from Polycystic Ovary Syndrome (PCOS) – PCO and PCOS are not synonymous. Symptoms of PCOS usually become apparent
during the teenage years
and can cause a range of issues, including irregular (or even absent) periods,
excessive body or facial hair (hirsuitism), male pattern balding, infertility,
obesity, hot flushes, sleep apnoea, skin discolouration, fatigue, high blood
pressure and mood swings. PCOS can also lead to more serious illnesses
later in life, including type 2 Diabetes, heart disease and certain cancers.
The Joy Of Soy
Soy has many reported
benefits. It is a low-cost protein that is
a good source of amino acids – perfect for vegans and vegetarians to fulfil
their need for this essential nutrient without eating meat. In 1999, the American FDA released a
statement claiming, “diets low in saturated fat and cholesterol that include
25mg of soy protein a day may reduce the risk of heart disease”
and they have allowed soy products to be marked as ‘heart healthy’. Soy has also been found to help prevent osteoporosis,
to lower blood pressure and to alleviate symptoms of menopause and hormone imbalance,
as well generally increasing wellbeing and energy levels. With such glowing reports on the benefits of
soy, surely it would make sense for PCOS sufferers to increase their soy
consumption? But what about it’s debated effects on oestrogen levels or on
We’ll take a look at these issues shortly.
What's In Soy?
Soy contains a significant
amount of phytic acid, alpha-linolenic acid and isoflavones. Let’s take a look
at each of these components.
Phytic acid is found
not only in soy, but also in foods such as cereal grains, nuts, and seeds.
Phytic Acid – The Cons
According to Wikipedia, “phytic acid chelates and thus makes unabsorbable
certain important minor minerals such as zinc and iron,
and to a lesser extent, also macro minerals such as calcium and magnesium”. Nutrients
such as these are important for women with PCOS. Studies have found, for
example, that PCOS sufferers are more likely to have low levels of magnesium in
their blood. And Zinc is critical for optimal fertility.
Hurrell et al
“concluded that phytic acid is a major inhibitory factor of iron absorption
(significantly reduces iron absorption) in soy-protein isolates but that other
factors contribute to the poor bioavailability of iron from these products.”
Women with PCOS commonly suffer from oestrogen dominance, a sign of which may
be menstrual flooding. Flooding may produce an iron deficiency anaemia, in
which case it may be helpful to reduce phytic acid intake.
By preparing food rich in phytic acid by cooking methods above 35 degrees Celsius,
such as boiling and roasting, as well as soaking and sprouting, this effect can
be significantly reduced.
Phytic Acid – The Pros
Heavy metals, such as lead and cadmium, can increase inflammation
and reduce insulin sensitivity. These are two main drivers of PCOS. Tsao et al
found that “the immobilized phytic acid can absorb heavy metal
ions, such as cadmium, copper, lead, nickel”
from liquid. This may help to reduce heavy metal toxicity.
Phytic acid has been found to reduce triglyceride levels, act as
(important in women with PCOS due to their higher levels of inflammation) and may
help to improve gut function by increasing the growth of the ‘good gut bug’
Gut issues are common in women with PCOS. Any improvement in gut health may
improve insulin sensitivity, reduce high oestrogen levels and increase nutrient
Excitingly, a study by Thompson et al
revealed that adding phytic acid slowed the glycaemic response to legumes. As
women with PCOS most often have insulin resistance and need very much to be
careful of foods that raise their blood sugar levels too far, this may be
important to note.
Alpha-linolenic acid (ALA)
Alpha-Linolenic acid (ALA) is an
essential omega 3 fatty acid. This means that you can’t produce it and need to
get it from your food plan.
Acid - The Cons
Alpha-linolenic acid undergoes oxidation more easily than other oils. This
means that it ‘goes bad’, or decomposes. This oxidization process will occur
when cooked, so foods containing ALA may not be suitable for cooking at higher
temperatures. This process can both affect the nutritional content of the food and
may potentially create health challenges. Because of this oxidation, products containing
ALA like soybean oil may be partially
hydrogenated as this reduces damage and shelf life. The process of partial
hydrogenation is not healthful. It produces trans fats, which have been linked
to coronary heart dis-ease, raised LDL cholesterol (thought of as ‘bad’
cholesterol) levels and a lowering a HDL cholesterol levels (thought of as
‘good’ cholesterol) (The idea of good and bad cholesterol is not quite
accurate, but that debate is for another day).
Acid - The Pros
Women with PCOS are more likely to suffer from stress, anxiety, fatigue and
sleep disorders. A study by Yehuda et al
showed that after 3 weeks of supplementing with alpha linolenic acid and linoleic
acid (an unsaturated omega 6 fatty acid), their was significantly reduced anxiety, as well as “better appetite,
improved mood, better ability to concentrate, less fatigue during the day,
better sleep and (improved) ability to organize themselves.” This author has
also previously shown that a mix of alpha
linolenic acid and linoleic acid “improved memory, thermoregulation (temperature
regulation) and sleep in humans.”
ALA may also reduce the rate of cancer cell growth.
As women with PCOS are at an increased risk of some forms of cancer, this omega
3 fat may provide a valuable and potentially life saving benefit. “Taken as a whole, studies suggest that dietary
polyunsaturated fatty acids (PUFAs)
- including ALA, play a (beneficial) role in cancer risk and progression”. Although
the amount needed to have this positive effect may require supplementation,
adding ALA rich foods to the diet may also help.
Women with PCOS are also at an increased risk of heart dis-ease, including
further ‘heart attacks’ following their first. A study by de Lorgeril et al showed
that people with increased ALA in their food plans where less likely to have a
second heart attack.
also know that women with PCOS are more likely to suffer from depression. ALA
may also be helpful here are well. “A study of over 50,000 women, conducted at
Harvard University, over a period of ten years, found that a higher intake of
alpha linolenic acid (combined with a lower intake of linoleic acid) was
positively associated with a significant reduction in depression in the same
It is the affects of isoflavones that are often debated
in female health and Polycystic Ovary Syndrome. A certain type of isoflavone is
known as a phytoestrogen, because they can mimic the effect of oestrogen within
the body. This
is where part of the ‘pro soy, anti soy’ arguments lay.
Women with PCOS are often what’s called ‘oestrogen dominant’, which means they
have either higher relative or total levels of oestrogen in their body and/or
they may be more sensitive to the oestrogen that is present.
Phytoestrogens may attach to the receptor on the cells, which means they can
potentially affect our body. The argument is this:
Phytoestrogens are considerably weaker than our own oestrogen. If we increase
the amount of phytoestrogens in our food plan, and so in our body, do we add
excessive oestrogen to an already overwhelmed system, or do we add a weaker
oestrogen that can take the place of at least some of the stronger oestrogen and
therefore reduce the oestrogen load?
Let’s look at some research…
Isoflavones – The Cons
A small study on 6 premenopausal women by Cassidy et al
found that “soy protein (60 g containing 45 mg isoflavones) given
daily for 1 month significantly increased follicular phase length (the first
half of your cycle) and/or delayed menstruation. Mid-cycle surges of
luteinizing hormone (LH) and follicle-stimulating hormone were significantly
suppressed during dietary intervention with soy protein.” As women with PCOS
already often have low levels of follicle-stimulating hormone (FSH) and often
don’t experience the LH surge needed for ovulation, this finding is of concern,
as are any delays in menstruation.
Isoflavones – The Pros
Breast cancer is an oestrogen driven cancer. This makes it relevant to discuss
in the context of whether phytoestrogens increase or decrease our risk of
oestrogen related dis-ease. Do they add to the oestrogen load or reduce it?
Nechuta. S.J. found
that “consumption of ≥10 mg isoflavones/d (more than 10mg phytoestrogens per
day) was associated with a non-significant reduced risk of all-cause and breast
cancer-specific mortality (death rate) and a significant reduced risk of
recurrence (of breast cancer).” This would indicate a benefit.
Jayagopal et al’s
study reveals that dietary supplementation with soy phytoestrogens beneficially
effected insulin resistance, blood sugar control and cholesterol levels. This
study was performed in women with Diabetes, so this is relevant to women with
Rivas et al found
that daily soymilk intake of 500 mL twice daily lowered blood pressure in women (and men) with mild
to moderate essential hypertension (blood pressure).
A small pilot study
in women with PCOS showed that when given 36 mg/d of genistein (a phytoestrogen) for 6 months, the
women experienced “improved total cholesterol levels, reducing low-density
lipoprotein (LDL) cholesterol and a significant decrease in the
LDL–high-density lipoprotein ratio (LDL-HDL). Triglycerides showed a trend
toward decrease.” These are all great things. There was no change in their
menstrual cycle, hormone levels, and body size or insulin resistance.
Yet, in another study by Khani et al, they found “after 3 months of genistein supplement
therapy there were no statistically significant differences in high density
lipoprotein cholesterol (HDL) and follicle stimulating hormone (FSH) serum
levels in (the) genistein and placebo group before and after treatment; however
serum levels of luteinizing hormone (LH), triglyceride (TG), low density
lipoprotein cholesterol (LDL), dehydroepiandrostrone sulfate (DHEAS) and
testosterone were significantly decreased after 3 months therapy in Genistein
group. Women with PCOS often have high general levels of luteinizing hormone
(LH), which adversely impacts on ovulation, and high levels of ‘male’ hormones
(dehydroepiandrostrone sulfate (DHEAS) and testosterone). This study would
point toward a benefit in women with PCOS including some soy in their food plan
to improve many of the challenges there women face.
Soy And Your Thyroid
The thyroid gland (a small gland at the base of the neck) is
extremely important. Amongst other functions, it is important for the
production of follicle stimulating hormone (FSH), and so ovulation and a
regular menstrual cycle. It is also your
energy ‘powerhouse’, and if it doesn’t work well, you may experience weight gain
and find it difficult to lose weight, depression, low energy, constipation,
infertility, increased risk of miscarriage and more. These signs and symptoms
sound a lot like those experienced by women with PCOS, don’t they? In fact, hypothyroidism (lowered production of
the thyroid hormones thyroxin, tri-iodothyronine, and calcitonin) is linked to
PCOS and affects many of its sufferers.
This makes it important to know whether soy intake effects thyroid function and
if so, how?
In a healthy cycle, there is a
surge of luteinizing hormone (LH) and raise in follicle stimulating hormone
(FSH) just prior to ovulation. Without this, ovulation does not occur. As women
with PCOS often either don’t ovulate or ovulate infrequently, changes to these
hormones are important.
A study by Duncan et al
looked at diets, which included either a low level or high level of soy
(isoflavone) and these hormones…
They found “the low isoflavone
diet decreased luteinizing hormone and follicle stimulating hormone levels
during the peri-ovulatory phase (the time around ovulation). The high
isoflavone diet decreased free T3 thyroid hormone (tri-iodothyronine) and dehydroepiandrosterone sulfate (a weak ‘male’
hormone’) levels during the early follicular phase and estrone levels during
the mid-follicular phase. No other significant changes were observed in hormone
concentrations or in the length of the menstrual cycle, follicular phase, or
luteal phase. Endometrial biopsies performed in the luteal phase of cycle 3 of
each diet period revealed no effect of isoflavone consumption on histological
dating.” This suggests that soy may exhibit an unwanted effect on key hormones
responsible for ovulation. However, as there was no change in menstrual length
or endometrial lining, whether this is biologically and clinically relevant is
also found that soy could increase the levels of sex hormone binding globule
(SHBG). SHBG is important for inactivating/reducing the effect of hormones such
as the ‘male’ hormone testosterone. Women with PCOS often have high levels of
testosterone, which can have signs and symptoms such as infertility, irregular
cycles, acne, excessive hair growth, depression and anger. Boosting SHBG, often
low in PCOS, can have profoundly positive effects.
Research suggests that thyroid cancer may be an oestrogen dependent cancer. Due
to this, and the debate above about whether soy isoflavones add to oestrogen
load or act to reduce it, it is important to ask the question… What effect do
soy isoflavones have, if any, on thyroid cancer? Horn-Ross et al
revealed “the consumption of traditional and
nontraditional soy-based foods and alfalfa sprouts were associated with reduced
risk of thyroid cancer. Consumption of “western” foods with added soy flour or
soy protein did not affect risk.”
Teas et al
found “soy protein isolate supplementation was not
associated with changes in serum thyroid hormone concentrations or thyroid end
points.” However, they did find surprisingly that seaweed ingestion did
increase serum thyroid stimulating hormone (TSH) levels.
A literature review by Messina and Redmond32 found that there
was little evidence that people with a healthy thyroid gland who were not
deficient in iodine experienced any adverse thyroid effects from consuming soy
foods, or isoflavones. However, women with PCOS often do have hypothyroidism.
There was one case study, which showed soy might inhibit the absorption of
thyroid medications in a hypothyroid patient. Although this indicated that soy might
change the required dose of thyroid medication, one case study alone is
certainly not enough evidence to make broad sweeping recommendations about the
effects of soy on thyroid function.
As “there remains a theoretical concern based that in individuals with
compromised thyroid function and/or whose iodine intake is marginal soy foods
may increase risk of developing clinical hypothyroidism. Therefore, it is
important for soy food consumers to make sure their intake of iodine is
adequate." As iodine deficiency is the worldwide leading cause of
hypothyroidism, this is not really surprising.
What About Genetically Modified (GM) Soy?
I don’t like the idea of genetically modified food. This is my personal
opinion. There have been arguments about the potential effects, both positive
and negative. I have read (debatable) reports showing that GM foods may
potentially seriously adversely affect growth and fertility (soy)
and have potentially toxic effects (corn).
I have a feeling in my gut that I don’t like GM. But can I give you strong,
overwhelming evidence to substantiate your avoiding it? No. This is a decision
that is for you to make. I feel the best, safest approach is to simply buy
Non-GM soy (and other food).
The Amount Of Soy In Modern Day Foods
We are consuming more soy in our foods now than ever before, which we are often
unaware of as it is added in traditionally ‘non-soy’ foods. I have concerns
about this increase. If we look at gluten, it has been reported that the gluten
content in bread has risen from approximately 4% to 17% over a generation. With
this rise we are seeing larger numbers of gluten intolerant people. Is the same
true for soy? This is yet to be seen. Research included in this report has
looked into soy components, soy protein isolate and other forms of
‘westernised’ soy, and were not found to have any real health effects. Only
time will tell.
So, The Big Controversial Question… Should You Include
Soy In Your Food Plan, Or Avoid It Like The Plague?
Despite often-negative press and passionately
adverse advocates, the research suggests soy may have benefits for women with
PCOS. Consuming soy helps to reduce blood pressure, inflammation, triglyceride
levels, anxiety and potentially reduce the risk of breast and thyroid cancer.
It also appears to be helpful in specific PCOS hormonal challenges like
reducing oestrogen dominance, reducing ‘male’ hormones, increasing sex hormone binding
globule (SHBG), reducing insulin resistance and inflammation and reducing the
increased risk of high blood pressure, poor cholesterol balance, Diabetes and
A small study indicated that larger amounts of daily soy consumption might reduce
- the active thyroid hormone). As T3 is
critical in thyroid health, and women with PCOS are more likely to suffer from
hypothyroidism, this needs to be considered. However, any theoretical potential
effect of soy on thyroid appears to be eliminated by consuming sufficient
iodine in one’s food plan.
Given the research, I believe that on
current evidence, soy is an important addition to the food plan of women with
PCOS. Simply choose organic, non-GM, ensure a balanced food plan replete in
vital nutrients and take a high quality multi-mineral (which is highly
recommended in women with PCOS, regardless of soy intake.
From PCOS to perfect health, with love,
Dr. Rebecca Harwin
'The PCOS Expert'
There is so much being said about soy which is both inaccurate and emotive, so feel free to share this article if you feel it can help.
Horn-Ross. P.L., Hoggatt
K.J., Lee M.M. (2001) Phytoestrogens and Thyroid Cancer Risk