Soy has become serious business in the past 50 years. It's been sold as the dream alternative to dairy; silky smooth and no saturated fat.
Plus, it is said to have cancer-preventing potential.
With the global soy food market forecast to reach more than $55 billion by 2015, the push has proved successful. In 40 years, production has more than quadrupled.
Not only is soy in our chai teas and cafe lattes, it is the basis of many protein powders, breads, baby formulas, sauces and supplements. Of course, we also consume it in the form of tofu, tempeh and tamari.
But, some say that the promotion of soy as the perfect protein for health lovers, is misleading to say the least.
New York Times best-selling author Dr Joseph Mercola has never been an advocate of soy.
Last month, he wrote a piece for the Huffington Post titled "The Health Dangers of Soy".
He asked if something that sounds so healthy could actually be dangerous, before concluding: "If you take the time to look into the actual science, then the answer is yes."
Studies, he said, have linked soy to malnutrition, digestive distress, immune system breakdown, thyroid dysfunction, cognitive decline, reproductive disorders and infertility - even cancer and heart disease.
Nor does he believe menopausal women should be prescribed soy supplementation.
"Pumping oestrogens into the body is not the way to address these issues, which usually can typically be helped with alternative methods such as a change in diet/nutrition, sleep habits, exercise, and natural supplements."
Mercola is a divisive doctor to say the least. He has been lambasted for his controversial claims and his critics say he spouts half-truths and makes irresponsible statements. But, he is equally considered to be at the cutting edge; unafraid to go against the grain of mainstream messages. He is immensely popular with many in the health and fitness industry and runs the world's most visited natural health site.
It is widely agreed that the studies on soy are conflicting. For all the studies touting its benefits, there are just as many that have worrying results. In its position statement on soy, the Cancer Council notes a notorious Australian case from the 1940s in which cows that were fed large quantities of phyto-oestrogens (a bioactive substance in soy) developed fertility problems and became less productive. As for links to cancer, it says, "The evidence for soy foods and cancer of the pharynx, oesophagus, pancreas, breast and endometrium is limited with no conclusion possible."
But, in counter-argument to Mercola's article, Dr Neal Barnard, Adjunct Associate Professor of Medicine at the George Washington University School of Medicine and Health Sciences, wrote that "researchers put [people's] concerns to the test".
They have found, he said, the diametric opposite of what Mercola says - that soy reduces cancer risk, boosts survival in breast cancer patients, lowers cholesterol, does not affect thyroid health and is an easily digestible protein.
However, Mercola is unwavering.
"Criticism is something we have to expect when we attack mainstream thoughts ... so there will always be people in your life and career who don't agree with you," he told Life & Style. "That said, I think the main reason more physicians aren't publicly aligning with my position on soy is that they just haven't carefully reviewed the details.
"I have a staff that helps me locate and research the thousands of pages of literature on this topic, but most physicians don't have that resource or the time or to do it themselves, so they rely on headlines and industry promotions which, for the most part, claim soy is the answer to good health."
Of the dramatic discrepancies between current studies, he said, "Studies seem contradictory because they usually focus on a very narrow endpoint that doesn't include looking at all the possibilities."
For instance, he cited studies of Asian women that show they have a decreased risk of breast cancer "possibly because of their consumption of soy products. But ... what you don't hear is these Asian women's soy diets were most likely very different from the Western soy diet, both in quantity of soy consumed and in the form it was consumed - fermented versus unfermented ... Additionally Asians also have a far higher incidence of certain cancers relative to non-Asians and it is unclear [why].
"What happens, then, is that people see the headlines ... sit there wondering which one is true because they don't realise they're being forced into a great big generalised statement on soy."
One of the big issues with soy is the level of processing it undergoes before it hits our palates.
"Soy isn't consumed just as a stand-alone food," Mercola said. "It is most commonly consumed in a highly processed form of soy protein which creates putrid proteins which are actually more toxic to your body than trans fats."
Sydney-based nutritionist Zoe Bingley-Pullin agreed. "I have a pretty strong opinion on soy products," she said.
They are "incredibly processed and often have sugar or salt, etcetera. Unsweetened soy milk [for example] isn't very palatable ... I don't think soy products are a health food ... the fat and salt content tend to be through the roof."
If you're going to have soy, go as unprocessed as possible and stick to the whole food (soybeans) or the fermented, organic version, Pullin suggests.
Mercola is also a fan of fermented.
"Fermented soy is a great source of vitamin K2 and K2 (combined with vitamin D) is essential in preventing osteoporosis, cardiovascular disease, dementia, and various types of cancer," Mercola said. "Traditionally fermented soy products include miso, tempeh, natto, and naturally fermented soy sauce."
The Cancer Council would like to see further tests in the future on soy, noting that study results vary according to fermented versus non-fermented soy, total soy versus soy protein and dietary soy versus urinary isofavones, a phyto-oestrogen substance.
"As with many other nutritional factors, there is a need for better quality, well-reported, larger and longer duration studies," they say.
"I agree that a number of lifestyle and dietary factors are leading to a radical increase in chronic degenerative illnesses, not just among Westerners, but all over the world," Mercola said. "But when it comes to soy, I stand by what I've learnt."
- Sydney Morning Herald
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