The soy industry has done its best
to fan women’s fears about bone loss, blame meat for the osteoporosis
epidemic and promote soy milk and other products as the solution.
Consumers who bone up on the issue,
however, will find that soy has only a rickety leg to stand on.And the soy industry itself knows this!
Between 2001 and 2005, I attended three symposia sponsored by the soy industry entitled “The Role of Soy in the Prevention and Treatment of Chronic Disease,” where I had the pleasure of watching embarrassed researchers squirm as they apologized for their failure to find a consistent bone-sparing effect and try to explain that the dose must have been either “suboptimal” or “excessive.”
In other words, they all know soy
“works” . . . now if they could only find the perfect dose, correct
formula or right age to initiate preventive treatment!
In 2006, very bad news came for the
soy industry when Yale researchers writing for the Journal of Nutrition
concluded:
“These data indicate that when soy
protein is substituted for meat protein, there is an acute decline in
dietary calcium bioavailability.”
This finding, of course, should
have exploded once and for all the myth that eating meat and eggs results
in a loss of calcium, leading the body to strip calcium from storage in
the bones, ultimately causing osteopenia or osteoporosis.
But no such luck.
To this day the myth gets
repeated, and if any science is cited at all, it’s most likely from an
article that ran in the Journal of Clinical Endocrinology and
Metabolism back in 1988. Let’s talk about that one:
The study involved 15 healthy young
people, divided into three groups. All three groups ate foods that
contained identical amounts of sodium, potassium, calcium,
phosphorous, magnesium and protein, but differing amounts of sulfur.
The first group (least sulfur) consumed soy
products; the second (moderate sulfur) consumed soy milk, texturized
soy protein, cheese and eggs; and the third (most sulfur) consumed animal
protein from meat and cheese. Those who got their protein from the animal
products lost 50 percent more calcium from their bodies than did those who
had only soy protein.The soy, egg and dairy people were in the middle. The researchers concluded, “The inability to compensate for the animal protein-induced calciuric response (calcium in the urine) may be a risk factor for the development of osteoporosis.”
When this study comes up — which it
often does in the pro plant-based diet literature – the authors never
mention that the 15 subjects spent a grand total of 12 days testing
each type of food. This was just enough time for their bodies to react to
unexpectedly high levels of sulfur proteins, but not enough time for the
body to normalize and handle the sulfur load.
Calcium homeostasis is normally well
regulated so that increased calcium loss through the urine results in
increased calcium absorption from the gut. This adaptive process may fail
to occur during short-term studies, though the human body is more
than capable of adjusting to the sulfur load of real foods when given a
proper time frame.
The fallacy of most other studies
linking sulfur-rich animals foods to high calcium excretion is equally
easy to find. The majority of the experiments feature overdoses of the
isolated amino acids methionine, cysteine and cystine without providing
adequate levels of vitamin B6 and the extra hydrochloric acid needed to
process this high amino acid load.
Notably, people and animals fed Real
Food have not experienced the same problems.
The B6 issue is critical because the
active form of B6 (pyridoxal-5-phosphate) is the coenzyme for the enzyme
needed for proper conversion of sulfur-containing amino
acids (cystathionine synthetase). The best and most available sources of
vitamin B6 are raw animal foods, such as raw meat, raw milk and raw
cheese. As it happens, these foods are also good sources of usable sulfur.
To date, only one study convincingly
suggests that soy might prevent osteoporosis.
Published in the May 2006 issue of Journal
of Nutrition, it pertains to natto, a fermented Japanese soybean
product rarely sold in the U.S. In the case of natto, the bone
building doesn’t come from the miracle bean itself, but from the Vitamin
K2 manufactured by the bacteria involved in the fermentation process.
Vitamin K2 is crucial for bone
health and conspicuously absent from soy milk or any other modern soybean
products. But don’t expect to find natto in the stores anytime soon as few
Americans appreciate its sticky coat, cheesy texture, musty taste,
sliminess, stringiness and pungent odor.
Butter and lacto-fermented
foods like sauerkraut are the best sources of vitamin K2 in western diets.
As for soy milk and other modern soy
products, more than 70 years of studies link soy to thyroid
problems, particularly hypothyroidism with its familiar symptoms of
weight gain, fatigue, malaise and lethargy. Hypothyroidism itself is a
known risk factor for osteoporosis.
Soy proponents, of course, believe
the phytoestrogens in soy promote bone health.
While it’s true that estrogen
receptors are found in bone, soy phytoestrogens are not true estrogens and
don’t reliably activate them. In any case, the key hormone for bone health
is not estrogen but progesterone. In that American women most often suffer
from estrogen dominance and progesterone deficiency, soy phytoestrogens
aren’t likely to help. And there aren’t any soy phytoprogesterones.
Last summer, the European Food
Safety Authority (EFSA) put the kibosh on proposed health claims that soy
stops osteoporosis. Of the fourteen studies submitted by the soy industry,
EFSA found only two that showed a possible benefit.
Those two reported an effect of
soy isoflavones at doses of 54 mg per day at the lumbar spine and femoral
neck, which was accompanied by a significant increase in markers of bone
formation and a significant decrease in markers of bone resorption. However,
the panel noted that such changes in BMD at the lumbar spine seen in short
term studies (six to nine months) could have “resulted from a change in
the remodeling balance which may not be retained in subsequent remodeling
cycles” and that “the evidence for a mechanism by which soy isoflavones
may exert an effect on bone mass and turnover in post-menopausal women
is weak.”
As for the other 12 studies, they
did not support bone health despite dosages of soy isoflavones as high as
200 mg per day. The soy industry declared it was “surprised” and
“disappointed.”
Disappointed? Of course.
Surprised? Hardly.
EFSA had earlier rejected three
petitions for a soy/heart disease health for similar reasons.
The takeaway? Other than the
vitamin K2 found abundantly in natto, soybean products have little to
offer our bones and much to harm them.About the Author
Kaayla T. Daniel, PhD, is the author of The
Whole Soy Story: The Dark Side of America’s Favorite Health Food
endorsed by leading health
experts, including Drs Joseph Mercola, Larry Dossey, Kilmer S. McCully, Russell
Blaylock and Doris J. Rapp.
She is Vice President of the
Weston A. Price Foundation, on the Board of Directors of the Farm-to-Consumer
Legal Defense Fund, and received the Weston A. Price Foundation’s Integrity in
Science Award in 2005. Kaayla has been a guest on The Dr.Oz Show, PBS Healing
Quest, NPR’s People’s Pharmacy, and many other shows.
Kaayla is known as The Naughty
Nutritionist™ because of her ability to outrageously and
humorously debunk nutritional myths.
You can find her on Facebook at facebook.com/DrKaaylaDaniel
and subscribe to her edu-taining blog at drkaayladaniel.com.
SOURCES
Daniel, Kaayla. The Whole Soy Story:
The Dark Side of America’s Favorite Health Food. (New Trends, 2005)
Daniel, Kaayla. EFSA rejects soy health claims for bone health and menopause.
Fujita Y, Iki M, Tamaki J et al.
Association between vitamin K intake from fermented soybeans, natto, and
bone mineral density in elderly Japanese men: The
Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) study. Osteoporos Int. 2012
Feb;23(2):705-14.
Ikeda Y, Iki M, Morita A, Kajita E,
Kagamimori S, Kagawa Y, Yoneshima H. Intake of fermented soybeans, natto,
is associated with reduced bone loss in postmenopausal women: Japanese
Population-Based Osteoporosis (JPOS) Study. J Nutr.
2006 May;136(5):1323-8.
Reinwald S, Weaver CM. Soy components vs. whole
soy: are we betting our bones on a long shot? J Nutr. 2010
Dec;140(12):2312S-2317S.
