Green Tea and Soy – the Synergistic Duo

You’ve probably heard of the moniker “blue zones,” which refers to areas of the world with the healthiest populations, and an unusually high number of centenarians – those lucky few who live beyond 100.  Or, maybe they’re not lucky.  Maybe they’re just doing some key things right.  Longevity researchers study these regions in an attempt to ascertain the secret behind the unique longevity and healthspans of these populations.  And, as you would guess, there isn’t just a single secret ingredient we can encapsulate to take in pill form (as Western medicine is prone to do).  It’s more like a secret sauce – a blend of lifestyle habits and dietary choices that work synergistically together.

One synergistic duo central to the Asian diet, including the blue zone of Okinawa, Japan, is green tea and soy. 

Green tea, alone, is a super star.  While all non-herbal teas are made from dried leaves, the extent to which the leaves are oxidized determines the type of tea.  “Green tea is made from unoxidized leaves and is one of the least processed types of tea.  For this reason, it contains the most antioxidants and beneficial polyphenols.”  Medical News Today.  Polyphenols are compounds found in plants, which are protective against ultraviolet radiation and pathogens.  It makes sense that if we consume these beneficial compounds through unprocessed plant foods, we get the same protective benefits that polyphenols bestow on plants.  In humans, polyphenols have been found to reduce inflammation and protect against cancer, among many, many other benefits.  And green tea is loaded with them! 

So what about soy?  Well, soy has been a hotly debated topic in the realm of health and wellness, particularly regarding cancer risk.  Historically, doctors have advised women with breast cancer to completely avoid soy.  The reason is that soy contains phytoestrogens (plant estrogens) called isoflavones, and because increased estrogen is associated with increased breast cancer risk, doctors have been wary of permitting patients to consume even phytoestrogens for fear of an estrogen-mimicking effect.  But, the most comprehensive studies have actually shown a decreased risk of breast cancer (and other cancers) from the consumption of soy, particularly if consumption began at a young age.  One reason is that soy doesn’t contain high enough levels of phytoestrogens to increase cancer risk, but is simultaneously rich in essential nutrients like B vitamins and magnesium, and is a complete protein, meaning it contains all nine of the essential amino acids.  Mayo Clinic.  The other reason has to do with the estrogen receptors themselves.  There are both alpha and beta estrogen receptors, with alpha creating an estrogenic (proliferative) effect, and beta creating an anti-estrogenic (non-proliferative) effect.  The isoflavones in soy at moderate levels have an affinity to bind with the beta estrogen receptor, which means they produce an anti-estrogenic effect, reducing breast cancer risk.  However, studies have shown that soy isoflavone supplements, which contain much higher phytoestrogen doses, may actually increase cancer risk.  So stick with normal, unprocessed food sources.  Ultimately, consumption of soy is up to you and your doctor, but take heart that the largest studies have shown a decreased or neutral risk of cancers associated with normal soy consumption.

Now let’s get synergistic.  Studies have shown that the anti-cancer effect of green tea and soy together is greater than their separate effects.  Check out this National Library of Medicine article discussing the mechanism through which the combination of tea and soy helps prevent breast and prostate cancers.  And this article from the Journal of Nutrition discussing a study finding that “[t]he combination of SPC (soy phytochemical concentrate) and green tea synergistically inhibited final tumor weight and metastasis [and] that further research is warranted to study the role of soy and tea combination as effective nutritional regimens in prostate cancer prevention.”  The abstract also specifically notes that the chemopreventive nature of the Asian diet is likely a combination of multiple factors, singling out soy and tea specifically, which are consumed in high amounts in Asia, and are likely behind the significantly lower rates of prostate cancer in Asian men.

So, what’s the takeaway?  Pretty straightforward!  Consider adding green tea and soy to your daily menu!  One easy way to do this is to add a healthy amount of unsweetened soymilk directly to your green tea, and find ways to add more soymilk, tofu, and edamame into your diet.  Another tip is to make sure to steep your green tea for at least a few minutes to ensure you’re extracting all of the goodness from the leaves.  Also, buy organic.  You don’t want to be drinking pesticide laden tea or soymilk, especially if you’re adding more of both to your diet.

Cheers to you and your health!