Soy Beans: Fights Menopause and Breast Cancer?
Like many plant foods, soy is a super underrated super hero. Now before you yell "GMOs!" or "estrogen!" at me, hear me out. Our friend soy is an exceptional character that has been nourishing the Eastern parts of the world for many years. Only relatively recently has the hype of soy made its way to the West, and though recent claims may have tainted its name, I'm here to clear it with the science. And the science tells us that soy foods have two thumbs up. With that said, if other factors regarding soy foods still concern you, they rightfully do. Research has a long way to go before disproving the GMO concern of soy crops, if they'll ever be able to. So go all the way and consume whole food based and organic soy foods. Even more, nourish your body with a completely clear conscience eating fermented whole soy foods like tempeh, which act as a probiotic, encouraging the beneficial effects of our healthy gut microbes.
Picture: Smith, K. (2017, July 17)
Soy's Series of Unfortunate Events...as Many Americans Know It:
Soy became all the rage as a super food back in the day, when people realized that the diet of the Okinawans in Japan (known to be one of the largest centenarian populations on Earth) consisted heavily of soy foods (21). But after word of phytoestrogens spread, all hell broke loose, and the assumption that phytoestrogens were estrogens and could cause cancer started a public panic. Eventually, it became generally accepted that phytoestrogens=estrogens=breast cancer. It turns out that these lovely legumes are actually good for you, especially for women.
The big debate today is if the phytoestrogens in soy mimic our own naturally-made estrogens, causing hormonal imbalances that could cause breast or endometrial cancer (8). Multiple studies of recent are actually suggesting the exact opposite. Increased intake of soy not only demonstrates lower likelihood of getting breast cancer, but it also indicates a lower risk of recurrence of breast cancer in survivors (8, 9, 10, 11). It gets better! Some studies even show that these may be even more promising for American women, as Western populations that consume soy foods appear to have more dramatic reductions in breast cancer risk than those of Asian descent (11).
One might ask:
“Do phytoestrogens from soy foods mimic our own estrogens, and bind to estrogen receptors in the body?”
“Isn’t the most common breast cancer an estrogen receptor-based cancer? So...if we're making our own estrogen, and eating phytoestrogens, won't we have excess amounts of estrogen that can bind to these cancer cells, promoting cancer?
Just when we think we have logic and common sense on our side, Mother Nature comes in and reminds us of the bigger picture. The biochemistry of living organisms is never a one-variable or black and white picture. There are countless connections to consider, and soy is no different. Foods are a package deal, and hundreds of chemical variables play a role in the outcome of every bite we take.While it is true that soy contains phytoestrogens called Isoflavones that can bind to estrogen receptors, know that phytoestrogens are not estrogens, they are distinct molecules that undergo distinct reactions with the estrogen receptors in our bodies. In this case, exactly how isoflavones bind is they key to understanding their unique relationship with estrogen receptors.
Human Estrogen vs Soy Phytoestrogen (Isoflavone) On Estrogen Receptors: There are two types of estrogen receptors in our bodies: alpha and beta. When bound, these receptors (we’ll call them ERs) cause a cascade of events that lead to chemical changes that play critical roles in the female body (5,6). Natural estrogens bind to these receptors with a high affinity, meaning they’ll latch on whenever they get the chance. Phytoestrogens, on the other hand, are more particular in the receptors they choose to acquaint themselves with. While they prefer the company of beta estrogen receptors (ER-b), how they interact with either ER-b or ER-a is very different than the way our estrogens interact. Long story short, isoflavones can bind these receptors to have a pro-estrogenic effect in some parts of the body, or bring things down a few notches via antiestrogenic effects in other regions of the body. This regulatory function deems phytoestrogens to be "selective estrogen receptor modulators" (SERMs), which is a fancy way to say they promote estrogen’s effects where they need to be high, and inhibit them where they should be low (5,6,17). This concept is so profound that pharmaceutical companies have made many synthetic alterations of this molecule, such as Tamoxifen and Raloxifene, in an effort to treat breast cancer (17,22,23).
The most common breast cancer in the U.S., accounting for 80% of breast cancer diagnoses, is endocrine receptor-positive (ER+) breast cancer. These cancer cells use receptors that bind estrogen and/or progesterone hormones to grow (11). Thus, elevated estrogen levels over long periods of time can promote cancerous growth, which is why the risk for breast cancer increases as a woman gets older. Breast cancer cells specifically use beta estrogen receptors to promote their growth (5,6,17). This is where the concern for phytoestrogens comes into play, being that phytoestrogens from soy prefer to bind the same type of beta receptors that breast cancer cells have. Well, how do they prevent cancer growth?Like I said, the catch is in how these molecules bind. Let’s dig deeper into the regulatory effects I brought up before:
Isoflavones: Inhibiting Cancer Growth by Blocking Production of Additional Endocrine Receptors: Phytoestrogens bind ER-b receptors, which means they block our naturally occurring estrogens from binding. Not only can they block our more reactive estrogens from binding, but soy isoflavones don’t have the coactivators that are necessary to activate production of more endocrine receptors, only estrogens do. So although phytoestrogens can bind to these hormonally sensitive cells, they sure aren’t promoting any progression from there, making the cancer less likely to produce more receptors to feed itself.
Inability to Promote Cell Growth: After decades of clinical trials, researchers have yet to encounter a consumable amount of soy food that can induce cancerous cell growth in women. Now, it is theoretically possible for phytoestrogens to promote cell growth. Sounds scary, because we don’t want potentially cancerous cell growth, right? Rest assured, the quantities needed to promote even remotely risky growth is so unrealistically large, that is has never been done in clinical trials, ever. It has only been accomplished under extremely dramatic rat experiments. I am talking removing the rats’ ovaries, removing their thymus, stimulating tumors, and then dosing them with isoflavones. Mind you, cell growth was only induced using isolated isoflavones, not soy foods. In some studies, it took about 100 times more isolated phytoestrogens than normally consumed to induce cancerous cell growth. (Remember that isolated isoflavones also don’t react the same way they would synergistically within a whole food!) To paint another picture, a 2008 study had to use the equivalent of 8–16 times the amount of normal dietary intake of soy in order to promote any cancerous cell growth, and still, that was in rats, not people. (That is the equivalent of 405mg of phytoestrogen concentrate in soy, compared to the normal 25-50mg whole food soy). This special relationship between phytoestrogens and ERs are actually part of the theory as to why they may be beneficial in both reducing breast cancer risks and breast cancer recurrences.
Predisposition to Repress Cell Growth: Phytoestrogens from soy are hundreds of times (literally, hundreds of times) more likely to activate repressive cellular pathways than to mobilize cell growth. Their actual biochemical interactions seem to deter cancerous cell growth rather than promote it.
But wait, there’s more! Aside from breast cancer, several studies are showing that these distinct interactions regulate receptors in other regions of the female body, balancing hormones to help prevent osteoporosis in women, act as an antioxidant, and be chemopreventive. And thinking logically, if the pharmaceutical field thought soy foods weren’t promising in their stabilizing nature, they wouldn’t be spending so much cash and efforts on creating medicines to mimic it (22,23).
Think About It: Breast and endometrial cancer are caused from excess estrogen in the wrong place at the wrong time. Phytoestrogens have anti-estrogenic effects in this case, not allowing our own estrogens to bind and promote cancerous growth. On the other end, they have pro-estrogenic effects in that after eating soy foods they have just enough of these phytonutrients coursing through the body to balance out low estrogenic concentrations in older women, thus potentially alleviating menopausal symptoms, such as hot flashes.Phytoestrogens are pretty badass.
Isoflavones and Menopause: How did soy stand against menopausal symptoms? The most significant results were seen while using soy extracts against hot flashes. A 2004 study made it a point to study the effects of soy extract in alleviating menopausal symptoms as an alternative to hormone replacement therapies. Results looked good, and women experienced up to a 44% reduction in hot flashes (24). A 2007 showed promising results for soy extracts as well, in which a double-blind, placebo-controlled study showed women experiencing dramatic decreases in hot flashes, decreasing for many by 40- 70%. We see the same trend in 2009, and finally in 2012, in a study that put a group of women on natural soy extracts for twelve weeks, observing decreases in both hot flashes and muscle stiffness by almost 60% (24-27).What's the good news? The good news is that many of the experiments were double-blind and placebo controlled, meaning not only did researchers use a control group to ensure that the effects occurring were legit, but neither the researchers nor the test subjects knew which group was taking the real supplements versus the placebo until results were shown. This is crucial in avoiding bias within the results. So when some of the studies showed an improvement by as high as 70%, this became potentially exciting news for natural methods of alleviating hot flashes for women.The bad news is, placebo effects were pretty high in many studies, which hurts the validity of isoflavones as a treatment. Furthermore, each study was executed so differently that the overall balance of results vary. There were simply too many differences in variables (subject group age, severity of symptoms, concentration of isoflavones used, to name a few), to confidently claim soy use to relieve menopausal symptoms. And because extracts were used instead of soy foods, we have yet to discover the amount of whole soy food that needs to be consumed in order to experience relief.The worst case scenario is it doesn't work for you, the best case scenario is that it does. There is enough information out there for women to start seriously considering adding tofu into their regular diet. And for the unfortunate women who suffer such severe symptoms that they are taking hormonal therapies, soy extracts offer a natural alternative. So what are you waiting for, ladies?
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Picture: Smith, K. (2017, July 17). Types of Soy Beans | Hunker. Retrieved January 15, 2018, from https://www.hunker.com/13427437/types-of-soy-beans