First, soy is one of the top 8 food allergens in the US (1), and food allergies in general are on the rise (2). Why we have increasing food allergies in this country and throughout the developed world, is probably a discussion for another day. But I believe that over-consumption of any one of these top allergens can lead to an allergy/intolerance if you didn’t already have one (3). And soy is almost as prevalent in everyday food products as gluten, so one could easily be over-consuming soy, without even knowing it. Just like gluten, soy flour is often added to sauces, gravies, dressings and marinades. Soy is also found in MSG, which is used to flavor many, many products. And soy lecithin, an emulsifier, is found in everything from margarine and ice cream to chocolate and herbal tea. According to Wikipedia,
“Soy products… are used as a low-cost substitute in meat and poultry products. Food service, retail and institutional (primarily school lunch and correctional) facilities regularly use such “extended” products… The soy-based meat substitute textured vegetable protein has been used for more than 50 years as a way of inexpensively extending ground beef without reducing its nutritional value.” (4)
In addition, soy milk, soy cheese, and other soy products are widely available for vegetarians/vegans, those who are substituting soy for dairy (because of dairy allergies), and anyone who is under the (incorrect) impression that consuming soy is healthy for you. Finally, soy and soy flour can often be found in gluten-free items as a substitute for wheat/gluten.
So you see, it is quite easy to over-consume soy, and the places in which it is found are just as sneaky as gluten.
Even if you don’t have an allergy, consumption of soy is actually considered bad for you. Let me clarify that by saying, unfermented soy is considered bad for you. Traditional Asian diets use a lot of fermented soy, and research seems to indicate that fermented soy in the form of tempeh, natto, miso and shogu (soy or tamari sauce) is actually fine (5, 6). So you can probably continue to enjoy your sushi and your chinese food, unless you have an allergy to soy. (Please note, that most soy sauce also contains wheat, so if you are reading this post because you are gluten-free, please seek out gluten-free soy sauce, which does exist). But soy in the form of tofu or soy milk (etc.) should be limited, because of a myriad of harmful effects. Barbara Minton at NaturalNews.com states that
In their natural form, soybeans contain phytochemicals with toxic effects on the human body…If they are not removed by extensive preparation such as fermentation or soaking, soybeans are one of the worst foods a person can eat” [emphasis mine]…”Unfermented soy has been linked to digestive distress, immune system breakdown, PMS, endometriosis, reproductive problems for men and women, allergies, ADD and ADHD, higher risk of heart disease and cancer, malnutrition, and loss of libido.”(7)
Perhaps one of the reasons unfermented soy is linked to so many complications is that it is considered an ‘anti-nutrient.’ That is, it actually inhibits the absorption of certain nutrients, particularly calcium, magnesium, iron and zinc. (8, 9) This can result in long-term nutrient deficiencies, especially serious for developing children as well as vegetarians and vegans.
Soy is also a natural source of estrogen, something that pregnant mothers, women trying to get pregnant, and infants should not consume in excess. Some studies have shown that too much estrogen early in a baby’s life might lead to reproductive issues later in life, and estrogen may effect fertility in women trying to get pregnant (10). In addition excess estrogen can wreak havoc on one’s hormones (males and females), which in turn can effect everything from sleep patterns and libido to physical development and psychology (11, 12, 13). There is even evidence that isoflavone (a phytoestrogen usually isolated from soy) blocks thyroid production (14) and can actually encourage the growth of breast cancer cells in the lab (15).
None of this paints a pretty picture for (unfermented) soy.
So what does this mean for you?
Let me start with a disclaimer. I am not a medical expert or health practitioner in any way. I am just a decent researcher. Please make your own judgements and decisions based on the articles that I have presented here. That being said, here’s how I would summarize the use of soy in your diet.
If you do not have a soy allergy, I would just take note of how often I eat soy, and make sure not to overdo it. Keep track of what you are eating, daily. If you cook for yourself, soy probably won’t be much of an issue. If you rely heavily on food products from the grocery store, or restaurants (especially fast food) please take note of what you are eating. Read labels (this holds true for anyone, anywhere, regardless of your dietary issues) and ask your restaurant servers and managers what’s in their food. Chain restaurants usually have nutrition pages online with their ingredients listed.
If you are pregnant, trying to get pregnant or have a young baby, I would limit my soy intake as much as possible. I would also probably limit the amount of soy eaten by developing children under my care.
If you have a dairy allergy/intolerance or are vegetarian/vegan, I would be very wary of the amount of soymilk, tofu and other unfermented soy that I was eating. I believe I made myself allergic to soy, because I thought I was intolerant to dairy and so started having soymilk with my cereal, and in my coffee, etc. Don’t replace cheese with soy cheese, or sausage with soy sausage (who wants to eat that stuff anyway?). If you have an infant with a dairy allergy, I would definitely consider using a formula other than soy-based. I don’t know what the options are on that front, and would like to encourage breast-feeding, anyway.
Some products (for reasons having to do with national regulation of soy products) don’t list soy protein or soy flour on their ingredients labels, yet they still contain soy. There are still many latent issues resolving how soy should be regulated, as well as its long term effects on human health. (16)
As with other food allergies, cooking for yourself is the number one best way to avoid having contact with soy. What about soybean oil (like in most mayonnaise) and soy lecithin (in almost everything!)? What I’ve read is that neither soybean oil nor soy lecithin contain enough of the protein that is responsible for allergies to be an issue for most people (17, 18). However, some people can still even have reactions to either, so if you have a known soy allergy, please consult your doctor about it. What about soy sauce? Same thing. Most people with soy allergies can probably tolerate soy sauce, but a small percentage may not (19). This last peice of news is probably the only silver lining in the cloud of soy sadness I’ve been feeling lately. Once my body gets back to normality after months and months of feeling ill, I may give some (gluten-free) soy sauce a try, because I really have been missing sushi and the taste of Southeast Asia.
I hope this clears up some issues and concerns about soy and what it means for your health. Please feel free to comment if you have anything you would like to add to the discussion.
And, by the way, what’s the connection to soy allergies and gluten allergies? I’ve read before and again that the weakened immune system that occurs from ingesting gluten can cause secondary food reactions. (Now that I’m looking for citations to back me up on this, I can’t seem to find any, but I know they exist, and will update this post when I find some.) Does this mean that once our system heals from a gluten attack (which in my case can take months), can we eat soy again? Maybe… but given all this information about (unfermented) soy, I won’t be seeking it out anytime soon.
*Written by Heather Jacobsen
(1) Mayo Clinic. Food allergies: Understanding food labels. Jan 4. 2011. http://www.mayoclinic.com/health/food-allergies/AA00057
(2) Hadley, Caroline. Food allergies on the rise? Determining the prevalence of food allergies, and how quickly it is increasing, is the first step in tackling the problem. EMBO Rep. 2006 November; 7(11): 1080–1083. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1679775/
(3) Barnes, Lisa (LCPH, MARH, Dip AIT). Food Intolerance Testing (Bath). 2010. http://www.lisabarneshealth.co.uk/food-allergy-bath
(4) Wikipedia. Soybean. Last updated July 9, 2011. http://en.wikipedia.org/wiki/Soybean
(5) White, Stephen Philip. Concerns Regarding Soybeans. http://rheumatic.org/soy.htm. 2006. rheumatic.org
(6) Minton, Barbara. Fermented Soy is Only Soy Food Fit for Human Consumption. NaturalNews.com. February 03, 2009
(8) Stephen Philip White.
(9) Hunter, Beatrice Trum. The Downside of Soybean Consumption. NOHA NEWS, Vol. XXVI, No. 4, Fall 2001, page 3.
(10) Konkel, Lindsey. Could Eating Too Much Soy Be Bad for You? Scientific American & Environmental Health News. November 3, 2009.
(11) Tulane/Xavier Center for Bioenvironmental Research. Phytoestrogens. eHormone. 2011. http://e.hormone.tulane.edu/learning/phytoestrogens.html
(12) Konkel, Lindsey.
(13) Phelps, Jim (M.D). Basic Information About Estrogen in Psychiatry. June 2005. PsychEducation.org. http://www.psycheducation.org/hormones/estrogenbasics.htm
(14) Minton, Barbara.
(15) Weed, Susun. Phytoestrogens – Friends or Foes? 2002. Feminist Women’s Health Network. http://www.fwhc.org/health/phytoestrogens.htm
(16) Wikipedia. Soy Allergy. Last updated January 12, 2011. http://en.wikipedia.org/wiki/Soy_allergy
(17) Canadian Food Inspection Agency. Soy Allergy. Government of Canada. April, 2010. http://www.inspection.gc.ca/english/fssa/labeti/allerg/soye.shtml
(18) Groce, Victoria. Soy Allergy. About.com. August 1, 2008. http://foodallergies.about.com/od/soyallergies/p/soyallergy.htm
(19) Pediatric Education Services. Let’s Talk About…Soy Allergy. Intermountain Primary Children’s Medical Center. 2006. https://kr.ihc.com/ext/Dcmnt?ncid=520408019