A closer look at Soy (with citations)

msarro
msarro Posts: 2,748 Member
edited September 19 in Food and Nutrition
Lately I've seen a lot of conversations about soy, so I did a bit of research myself and here is what I found. I included citations so that I can show I have actually done the research, and I'm not pulling facts out of my bum :)

I invite anyone to discuss this, but please be able to cite sources for what you say. No "I avoid it because I don't trust it" talk.


Phytoestrogens (Men shouldn't eat soy because they'll never get muscular and they'll grow moobs) -

This seems unlikely. There have been no conclusive studies that I can find, and most of it seems to be based on the misconception that Testosterone and Estrogen exist in set levels, and consuming one causes one to immediately unbalance the other.

Further, if this was the case, similar effects would manifest in nuts, meats, breads, vegetables and fruits. They all contain isoflavones, a.k.a. phytoestrogens (http://www.informaworld.com/smpp/content~db=all?content=10.1207/s15327914nc5402_5). Of all items that contain phytoestrogens, soy is not nearly the highest in concentration.

Also, most studies indicating cancer as caused by soy products have been unreliable. If a study is unreliable (cannot be replicated) then how much can you really trust the link? Especially when other studies seem to point to soy preventing cancer (http://www.fda.gov/Fdac/features/2000/300_soy.html).

Complete Protein (You MUST Eat soy products with beans to get a complete protein) -

This seems to be a bit muddier. The FDA itself lists soy as a complete protein (http://www.fda.gov/Fdac/features/2000/300_soy.html). Further, the PDCAAS score for complete soy protein is 96 for whole soybeans, 74 for isolates (Protein Quality-Report of Joint FAO’/WHO Expert Consultation, Food and Agriculture Organisation, Rome, FAO Food and Nutrition Paper 51, 1991.). This puts it on par with milk (91) and eggs (97). However, a ton of other sites out there state the opposite. To be quite honest, I'm not sure which I believe. The FDA can be a bit wonky sometimes.


So, that's what I was able to find, and where I found it. I would like to know, because I'm having a heck of a time sorting out all of the details.

Replies

  • msarro
    msarro Posts: 2,748 Member
    Lately I've seen a lot of conversations about soy, so I did a bit of research myself and here is what I found. I included citations so that I can show I have actually done the research, and I'm not pulling facts out of my bum :)

    I invite anyone to discuss this, but please be able to cite sources for what you say. No "I avoid it because I don't trust it" talk.


    Phytoestrogens (Men shouldn't eat soy because they'll never get muscular and they'll grow moobs) -

    This seems unlikely. There have been no conclusive studies that I can find, and most of it seems to be based on the misconception that Testosterone and Estrogen exist in set levels, and consuming one causes one to immediately unbalance the other.

    Further, if this was the case, similar effects would manifest in nuts, meats, breads, vegetables and fruits. They all contain isoflavones, a.k.a. phytoestrogens (http://www.informaworld.com/smpp/content~db=all?content=10.1207/s15327914nc5402_5). Of all items that contain phytoestrogens, soy is not nearly the highest in concentration.

    Also, most studies indicating cancer as caused by soy products have been unreliable. If a study is unreliable (cannot be replicated) then how much can you really trust the link? Especially when other studies seem to point to soy preventing cancer (http://www.fda.gov/Fdac/features/2000/300_soy.html).

    Complete Protein (You MUST Eat soy products with beans to get a complete protein) -

    This seems to be a bit muddier. The FDA itself lists soy as a complete protein (http://www.fda.gov/Fdac/features/2000/300_soy.html). Further, the PDCAAS score for complete soy protein is 96 for whole soybeans, 74 for isolates (Protein Quality-Report of Joint FAO’/WHO Expert Consultation, Food and Agriculture Organisation, Rome, FAO Food and Nutrition Paper 51, 1991.). This puts it on par with milk (91) and eggs (97). However, a ton of other sites out there state the opposite. To be quite honest, I'm not sure which I believe. The FDA can be a bit wonky sometimes.


    So, that's what I was able to find, and where I found it. I would like to know, because I'm having a heck of a time sorting out all of the details.
  • MTGirl
    MTGirl Posts: 1,490 Member
    Interesting research msarro - thanks for putting in the time and effort! The jury is still out for me, but at least there is solid research!

    What I would like to research - when I have a few minutes, busy season here! - is the propegated reproductive health effects on men. If I get to it, I'll let you know what I find out :flowerforyou:
  • rethun01
    rethun01 Posts: 167
    The only reason I avoid soy is because I don't like how certain soy products taste. I just can't do soy milk. Not even in my coffee. That is one way to ruin my skinny vanillla latte... or so I learned the hard way.

    But other than that I like soy alot. It is incredibly filling, but doesn't make me feel bloated and icky.

    Thanks for the research. I :heart: researched posts.
  • godsgrl
    godsgrl Posts: 49
    I think one of the main problems with soy that it is quite often genetically modified (unless you know you are getting organic) and no one is really sure what gm foods do to us, yet. I'm quoting a blog that is quoting a study, but check out her research ... http://fanaticcook.blogspot.com/2009/01/disturbing-findings-in-rats-fed.html ... it's quite scary. And here's another link: http://www.soyonlineservice.co.nz/02gmsoy.htm

    Soy is quickly becoming a food additive much like corn -- in other words, it's in everything. And we just don't have all the info yet. Until we know, I'd at least try to avoid all gm foods (including corn, etc) until enough years have passed to get sufficient data.

    Also, consuming raw soy, which is the current wave, has not been studied. Soy has not caused problems in history but was traditionally consumed fermented in various ways. Like most beans and grains, soy contains high levels of phytic acid that can greatly interfere with the assimilation of nutrients when consumed raw. Like grains and beans, soy is best consumed after a long soaking and/or fermenting that helps neutralize phytic acid. As history has fortold with the grain industry, most processors will not take the time to properly prepare soy products. Time = money = who cares about our health! :frown:

    Here's a fun article. Not sure how accurate it is, but here is goes: http://www.westonaprice.org/soy/darkside.html
  • katrana
    katrana Posts: 66 Member
    Unfortunately I can't get access to this original research article but here is the abstract:

    Protective effects of Asian dietary items on cancers - soy and ginseng.
    Asian Pac J Cancer Prev. 2008 Oct-Dec;9(4):543-8.

    Dietary factors are regarded as exerting major influences on cancer development in various organ sites and in Asia there is particular interest in the potential preventive effects of foodstuffs such as soy products and gingseng. The so-called phytoestrogens, like genistein and daidzein in soy, can bind to estrogen receptors and therefore interfere with the action of estrogen itself, a well-established risk factor for breast, ovarian and endometrial cancers. Although not all results are consistent, there is good evidence for protective influence of soy products against all three of these cancers. In addition, there have been many reports of preventive effects in the prostate. With ginseng, whether white or red, the included polyphenol compounds and saponins may play roles in many different organs, although preventive potential is perhaps best documented for gastric cancer. The traditional diets in Eastern Asia may need more emphasis in efforts to combat the growing problem of cancer in this region of the world.


    Basically, the way I interpreted this was that soy may actually be PROTECTIVE against breast cancer because it can bind to the estrogen receptor and thus block estrogen from binding. I will look into more studies too.
  • katrana
    katrana Posts: 66 Member
    another one:

    Planta Med. 2008 Oct;74(13):1656-65. Epub 2008 Oct8
    Selective estrogen receptor modulators and phytoestrogens.

    Scientific achievements in the last two decades have revolutionized the treatment and prevention of breast cancer. This is mainly because of targeted therapies and a better understanding of the relationship between estrogen, its receptor, and breast cancer. One of these discoveries is the use of synthetic selective estrogen modulators (SERMs) such as tamoxifen in the treatment strategy for estrogen receptor (ER)-positive breast cancer. Hundreds of thousands of lives have been saved because of this advance. Not only is tamoxifen used in the treatment strategy for patients who have breast cancer, but also for prevention in high-risk premenopausal women. Another synthetic SERM, raloxifene, which was initially used to prevent osteoporosis, is also as effective as tamoxifen for prevention in high-risk postmenopausal women. In certain regions of the world, particularly in Asia, a low incidence of breast cancer has been observed. These women have diets that are high in soy and low in fat, unlike the Western diet. Interest in the protective effects of soy derivatives has led to the research of phytoestrogens and metabolites of soy that are described by some as natural SERMs. As a result, many clinical questions have been raised as to whether phytoestrogens, which are also found in other natural foods, can protect against breast cancer. This article reviews the development and role of the more common SERMs, tamoxifen and raloxifene. In addition, this paper will also highlight the emerging studies on phytoestrogens and their similarity and dissimilarity to SERMs.


    Take this with a grain of salt, because correlation =/= causation. I didn't get to read this article so I don't know if they did any controlled studies, but it could be that the reduced cancer rate in people that eat a diet high in soy could be cause of other components of their diets (such as fish, increased levels of vegetables, increased exercise, etc). However, I am going to continue to eat soy. It also has many heart-protective properties (which I can link the data to later). My primary source of soy is edamame, which I really enjoy eating! It is tasty, filling, and low in calories.
  • paulamma1
    paulamma1 Posts: 544 Member
    Settling in with my bag of popcorn.
This discussion has been closed.

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