Maybe a health food, maybe a toxin? Not to knock the Tofurky, but soy seems to have been on some kind of nutrition roller coaster in the past few years, judging from the headlines. It's been bothering me, the not knowing about soy, while my child continues to gobble edamame in quantity. So here's the basic lowdown.
Some of the biggest hopes for and worries about soy stem from the fact that soy's rich in isoflavones (genistein and daidzein), chemicals which behave like estrogen and, possibly, anti-estrogen (!) in the body. They're not really sure how isoflavones work in our bodies. They may replace estrogen (which would be positive, if stemming the spread of estrogen-receptive breast cancer cells, for example, by replacing them) or they may mimic estrogen (which would be negative, if disrupting the endocrine system of a developing baby, for example). Soy's chemical makeup also may act as an antioxidant. Complicated plant. I'm surely no scientist and welcome any helpful analogies....
On the hopeful side, some argue that avoiding meat sources of protein (high in saturated fat, high on the food chain and therefore high in toxins) by
any means necessary substituting soy protein can't be a bad idea, especially since many cultures have eaten soy for hundreds of years without adverse effects. Scientists still theorize that soy may be helpful in preventing heart disease, lowering blood cholesterol and blood sugar, preventing prostate cancer and osteoporosis, and lessening menopausal symptoms, but the jury is still out (and much-lauded heart claims may be overrated). Most research is unclear about the reality of soy's role in our diet, so doctors tend to advise people to eat it in moderation (surprise!), some on the basis that it's been eaten for so long in many Asian countries whose health profiles are vastly better than here in the US.
On what some have called the Dark Side of Soy, soy may cause breast cancer, disrupt thyroid function, cause premature puberty in girls, and may in fact be a problematic food source for infants due to possible hormone disruption during development. There has also been speculation that soy decreases mental function and sperm count in men. Sally Fallon, of the Weston A. Price Foundation (proponent of traditional foods including grass fed meat, raw milk, and lacto-fermented goods), believes that soy is dangerous to eat unless it's properly fermented. She highlights the seemingly obvious point that Asian societies have traditionally eaten small amounts of tofu/miso/tempeh, not highly-processed soy protein products we see in many supposed 'health' foods like meat substitutes.
Of those scary claims, and the laudatory ones too, it appears that the jury's still out (there's no solid evidence to back up most of the theories pro or con).
Because we lack information about most prospective positive benefits to soy, and it's a common allergen, some advise parents to feed babies soy formula only if a child has a milk allergy and there's a compelling reason to choose soy. Claims that soy might prevent allergies or cure colic are two common (unsubstantiated) reasons for its introduction but avoidance due to the theoretical possibility of hormonal/endocrine disruption due to soy formula hasn't been proven either.
So what do they know for sure about soy? Not much.... But here's a few (tofu) nuggets:
- Research this fall showed that genistein (an isoflavone in soy) in soy infant formula is protective against rotavirus (a really unpleasant and common childhood illness for which they recently introduced a vaccine as well).
- People who have had kidney stones should completely avoid soy because it contains oxalates, which promote the formation of the most common type of kidney stones.
- Research has shown that a diet replacing meat protein with soy nuts is effective at reducing a host of risk factors (abdominal fat, low HDL, high LDL) that together form a "metabolic syndrome" seen in postmenopausal women at risk for coronary disease. Soy nuts (not soy flour) effectively lowered blood sugar and LDL levels in this cohort.
I think my cautious takeaway from this may be to judiciously limit the edamame, as they're not fermented (to make the soy more digestible) and to consume limited amounts of organic, non-GMO tofu, tempeh, and miso, truly traditional soya foods. I'm sure we can come up with another satisfactory salt-bearing device for EGirl!