The Skinny On Soy

Back in 2002 when the Women’s Health Initiative concluded that supplemental estrogen led to higher rates of breast cancer, blood clots and cardiovascular disease, the medical community resurfaced in a panic. Prior to this landmark study, estrogenic hormone replacement had only ever been touted for its positive side effects, such as improving bone health and reducing menopausal symptoms. Drug companies everywhere set out to design a physician’s ideal prescription – a selective estrogen receptor modulator.

In simpler terms, the industry needed a product that could offer consumers the best of both worlds. A drug that could provide pro-estrogenic effects in tissues like bone (where estrogen proved beneficial), but anti-estrogenic effects in others like breast tissue (where higher estrogen levels were associated with increased cancer risk). But how could a single hormone behave so differently in two regions of the body?

The answer lies in that there are two types of estrogen receptors within our anatomy: alpha and beta. And how a certain tissue or organ responds to estrogen has to do with which type of these (alpha or beta) receptors it has.

So where does soy fit into to all of this? Where does a simple legume find its place in the middle of a narrative polluted with rumors of thyroid disease, cancer and man-boobs (among other eminence)?!

It all started with the discovery of a certain class of phytochemicals (or “plant” chemicals) called isoflavones. Soy foods such as soy beans, edamame (soy beans harvested at 80% ripeness), miso, tofu, and tempeh are rich in these isoflavones - a molecule that vaguely resembles our own estrogen on a molecular level.

There's one problem. The media LOVES to end the narrative right there.

“If soy has these estrogen-like compounds, it must lead to things like breast cancer and male feminization, right?!”

In reality, the phytoestrogens from foods like soy behave entirely distinct from our own endogenous estrogen. Unlike the estrogen we produce, soy estrogens (or isoflavones) preferentially bind to beta estrogen receptors.

It’s for this reason that tissues predominantly containing alpha receptors, such as the liver, uterus, prostate and breast are not negatively impacted by soy consumption. In fact, the plant-estrogens in soy can sit in these estrogen receptors (as if to “save a seat”), preventing our own estrogen from binding to those receptors and exerting much stronger estrogenic effects. This leads to a cascade of benefits that ultimately prevents the liver from pumping out too many blot clotting factors, promotes the improvement of menopausal symptoms, and significantly reduces the risk for endometrial, breast, prostate and gynecological cancers.

The consumption of soy has been shown to not only reduce the risk of breast cancer but also improve breast cancer survival, reduce recurrence rates and extend longevity.

In fact, women who consume soy foods (ideally starting in adolescence) have between 30-50% reduced risk of breast cancer, and the countries that consume the most soy like Japan have some of the lowest breast cancer occurrence rates worldwide.

Additionally, studies like this one have found that consumption of just one serving of soy milk per day results in a whopping 70% reduction in the risk of prostate cancer, thanks to the tumor-suppressing effects of beta cells located on the prostate gland.

With regards to skeletal health, human bone cells contain beta estrogen receptors. This explains the breadth of research associating soy phytoestrogen consumption with reduced bone loss, enhanced bone mass formation, and a significantly reduced risk of bone fractures with just a single serving (5-7 grams of soy protein) consumed per day.

Soy has also been shown to lower cholesterol and aid in the prevention and reversal of clogged arteries, helping prevent the number one killer of men and women in our nation (heart disease), as well as reverse related conditions such as erectile dysfunction.

The bottom line: Soy is perfectly safe and actually protective for men and women alike.

However, keep in mind here - variety is the spice of life! You would never eat six servings of “kidney-bean protein isolate” in one day, and the same should go for any other bean or legume (such as soy). Variety in our protein sources is critical for a diverse microbiome as well as to ensure we ingest plenty of different amino acids, phytochemicals and disease-fighting compounds daily.

Consume this healthy legume in moderation like any other source of protein (<3 servings per day), ideally in organic, minimally processed forms.

And fermented with live and active cultures like tempeh or miso? Now we’re in BONUS POINTS territory, friends.

Fermentation makes soy more digestible and adds flavor. It also deactivates soy’s natural phytic acid and enzyme inhibitors, which can affect protein absorption and negatively impact the bioavailability of minerals like iron, zinc and calcium.

Note: Tempeh, miso, tamari and shoyu are fermented. Tofu is not fermented, but tofu does not negatively affect mineral or protein absorption because of the way that it’s made.

More highly processed soy foods such as burgers and products with isolated soy protein or soy flour are best left as occasional treats. When a food is made from "soy protein isolate”, that’s typically a sign that it’s more heavily processed and could contain additives, fillers, excessive amounts of salt, sugar or other appetite-enhancing compounds. Some highly processed forms of soy include textured vegetable protein, protein powders, and soy flour-based meat analogs.

Finally, let’s address the elephant in the room here. Beer lovers, focus up.

Hops actually have higher levels and more potent phytoestrogens than soy. So if you’re really worried about phytoestrogen consumption, you might consider a hard pass on the p