NUTRISPEAK by Vesanto Melina MS, RD
• Soy has been the focus of considerable controversy. The roots lie in good and bad science and in the fact that soy poses a threat to the animal products industry. As many shift towards plant foods, interest in soy arises, in part for its top-quality protein. Research also establishes its protection against cardiovascular disease and hormone-related cancers (prostate and breast).
Reliable science on soy
Soy’s components – isoflavones – can have the following effects:
- In people with hypothyroidism – and/or who are iodine deficient – soy can affect the thyroid gland. These individuals should limit soy intake until the problem is corrected. Solutions can involve adjusting the dosage of thyroid hormone for those with hypothyroidism and consuming adequate iodine – from a little iodized salt, supplement or sea vegetables – to avert deficiency.
- Isoflavones can bind to some, not all, of our estrogen receptors. While a decade ago, soy raised theoretical concerns, it has since been established isoflavones don’t mimic estrogen’s potentially damaging effects – just the beneficial ones. Moderate consumption – one or two servings per day – protects against breast cancer. This protection may be linked especially to childhood soy consumption. For those who have had breast cancer, soy can reduce the risk of recurrence and death. Soy may also reduce hot flashes and wrinkles.
For men, there’s compelling evidence that one or two servings daily of tofu, soy milk, edamame, or tempeh can reduce the risk of prostate cancer and lower LDL cholesterol. Studies show men who regularly consume soy foods have a 26% reduced risk of prostate cancer.
The misapplied science
Research has been misunderstood or inappropriately generalized. For instance, two men who regularly consumed 12 or more servings of soy daily – one drank three quarts of soymilk a day – eventually developed health problems, such as enlarged breast tissue and loss of libido. In both cases, when intake was reduced, their health and libido reverted to normal. Yet these cases were distorted, sensationalized and led to fears among men. Focusing one’s entire diet on any item will undermine health and such imbalance leads to nutrient shortages. These cases shouldn’t be construed to show that moderate intakes of soy are unsuitable for men. Soy shouldn’t crowd out other health-supportive plant foods.
Other anti-soy propaganda – typically originating from competing industries – was based on studies using rats or parrots as subjects, both of which are unsuited to diets of raw soy. We humans shouldn’t eat raw soybeans either. However, we thrive on several daily servings of organic – in Canada, that also means GMO-free – soy foods, prepared in traditional ways.
Soy’s various forms
Different forms provide various advantages. Tofu and soy milk have proven nutritional features and health benefits, established over centuries of use across Asia. The soaking and cooking during preparation of soy milk and tofu improve mineral availability. Tempeh’s fermentation process further supports mineral absorption. Edamame – young, whole soybeans – can be eaten from the shell after steaming. For those who want to impress their meat-loving friends and family, amazing products can be made with soy protein isolate, which is highly rated in terms of protein quality and suited to various dietary preferences or occasions. Choose organic and GMO-free products as much as possible. Like a raw chicken breast, tofu may not be appealing, but when prepared well, it’s delicious. Google soy recipes and see Cooking Vegetarian by Melina and Forest (available through bookstores and libraries).
Vesanto Melina is a registered dietitian and award-winning author based in Langley. 604-882-6782 www.becomingvegan.ca www.camd58.sg-host.com