Is soy milk good for you or not?
'Soy milk's bad for you" quipped a friend as I ordered a soy latte. "I don't know if it is or it isn't," I responded, but admitted to being aware of the recent resurgence of an anti-soy zeitgeist permeating the culinary and coffee-loving world.
My local barista told me he never drank soy milk as he didn't want to grow "man boobs", yet a menopausal friend said her symptoms diminished when she made the switch to soy products. Soy confused?
It is true the wheels fall off the soy bandwagon every few years. In New Zealand in 2012 there were calls for soy-based baby formula to be taken off supermarket shelves after research emerged suggesting exposure to soy in the womb or in childhood could affect female fertility. And then there's the Bonsoy story, where more than 600 Australians have joined a class action against Bonsoy Soy milk, claiming they got sick from an overload of iodine. With all the good and bad press surrounding the legume it's hard to make sense of what types of soy one should be consuming.
Professor Mark Wahlqvist is a long-standing member of the World Health Organisation's Nutrition Advisory Panel. He is also editor of the Asia Pacific Journal of Clinical Nutrition. His work on the legume is extensive. He says it's vital to distinguish between traditional and modern forms of soy.
Traditional forms of soy foods include tofu, bean curd and tempeh (principally used in Indonesia). In Japan, traditional forms include miso soup, edamame and a fermented form of soy called natto. "Traditional forms of soy are all fairly intact, they haven't been broken down into components; the whole bean is eaten, or has been processed by the traditional food technology, like fermentation," Wahlqvist says.
The forms of soy consumed in the West are often based on soy isolates, where the protein is used as a food ingredient, so the type of soy we ingest here is not the type getting all of the positive spin, nor is the way we consume it. In Asia, soy products in their original form are used as condiments and not to excess. "In the West, soy is used in reconstituted products like soy milk, meat look-alike products, protein bars and after-gym-workout shakes," Wahlqvist says.
He says consumers should be mindful that when they consume products that do not contain soy in its pure form, they may miss out on the health benefits that exist in the type consumed in Asian countries.
That said, he also cautions against soy "scare" stories that do not give the whole picture; for example, that soy causes thyroid suppression. It's true soy does contain goitrogens - substances that depress thyroid function, but he says: "Even though the goitrogenic activity of soy is low, it's true that it could be exacerbated by iodine deficiency with resultant goitre and thyroid disease. But this applies to several other foods like brassica [cruciferous vegetables] none of which we would want to discourage. The real issue is dealing with iodine deficiency."
Earlier in 2013, Food Standards Australia New Zealand brought in a law allowing manufacturers to make health claims about a range of foods including soy products. Prior to this, nutritional claims could be made but not health claims such as "this food is good for strong bones".
Wahlqvist says: "I resisted any move towards a health claim for soy protein [in the US and Australia], and still do now that health claims are possible in Australia, as it would have, has and will encourage so-called 'value-addedness' of food by splitting it apart." He says more studies are needed before any value-added benefits can be made on non-traditional soy products.
John Eden, associate professor of reproductive endocrinology at the University of NSW, says we have nothing to fear when it comes to the endocrine system and soy products in the amounts typically consumed in the West.
That said, he asserts glowing reviews can be just as confusing to the soy story. He and his team published a study in 2001 concluding soy products, including milk, powders, cheese, the works, do not help with the incidence of hot flushes in menopausal women.
A similar peer-reviewed study conducted in 2009 in Germany concluded the same thing.
What about women trying to get pregnant, should they avoid soy products? Eden says this is another myth and that estrogenic activity is everywhere.
"It's in the water, other foods, cosmetics, everywhere - the quantities in soy are little. To assert that soy products can change endocrine system function is nonsense, it really does come down to having a balanced diet," he says.
Can soy alter a woman's menstrual cycle?
"Yes," Eden says, "but not significantly. As long as a woman is having at least six periods a year, that is considered 'normal'. Exactly how soy achieves a delay effect is open to speculation but more importantly it is not harmful. Just before I picked up the phone to you I downed some cheese, and a soy drink."
- Sydney Morning Herald