Inflammation
Soy allergies and soy sensitivities
by Dixie Mills, MD
At the clinic, we will often recommend soy as a natural, therapeutic treatment to
help women with many aspects of their health, including hormonal balance, because
so many of our patients find it helpful. As I discuss in my article on the
soy controversy, researchers have found soy to be safe in therapeutic amounts.
Yet some people continue to talk about soy as though it were poisonous, or as though
it will have detrimental effects on our children. While this is not true, a small
proportion of people do have sensitivities or allergies to soy. So it is worth looking
at what can happen when you’re sensitive or allergic to soy, and how you can work
with this sensitivity to decide whether soy is something you want to include in
your diet.
Soy sensitivity versus soy allergy: what’s the difference?
When it comes to allergies and sensitivities,
every woman’s body uses and digests soy proteins, sugars, and isoflavones differently.
Sensitivity to soy can create, among other things, digestive problems and inflammation.
This can be a genetic issue, a function of diet, a lack of digestive enzymes or
co-nutrients, or an imbalance of the beneficial bacteria that live in the digestive
tract. But difficulty digesting soy, and being allergic to the food, are not the
same thing. An allergy is a situation where your body considers a substance to be
foreign, and marshals an immune response to it — sometimes a strong one.
Soy sugars. When you’re sensitive to soy, digestive problems
occur because soy contains two sugar compounds, raffinose and stachyrose,
that humans are unable to break down without some help. Soy isoflavone molecules
are also attached to sugar molecules (for example, genistin is the glucoside,
or sugar-containing form of the isoflavone genistein), and they, along
with soy proteins, must be processed in the colon by native bacteria that produce
gases such as carbon dioxide, hydrogen, and methane. Some argue that only fermented
soybean products like soy sauce and miso are safe because the sugar molecules in
soy get split off in the fermentation processes used to produce them.
Soy and trypsin. Others claim that only fermented soy
products and tofu are digestible, because raw soybeans contain trypsin inhibitors
or other “antinutrients,” which they say counteract our ability to digest and absorb
proteins. But many legumes and other plants contain trypsin inhibitors and other
factors that affect their digestibility, including green beans, kidney beans, and
lima beans — even corn!
Soy, digestive enzymes, and gut flora. Some legumes may
be completely indigestible, even when cooked. But not all. And most people are able
to split the sugars off and break down various legume proteins — though not everyone.
The discomfort some people experience after eating soy and other beans can depend
on their digestive
enzymes and the type or amount of
bacteria in their gut. It can also depend on the variety of bean, and
how and when it is harvested.
Soy and the thyroid. Some women with thyroid concerns
may also experience a response to the isoflavones in soy, but this directly relates
to thyroid function rather than an inflammatory response per se, and may be managed
by moderating intake and correcting an iodine and/or selenium deficiency. See our
article on goitrogenic
foods for more information.
An allergy to soy is a very different matter — one that is uncommon, fortunately.
But there is a great deal of confusion and misinformation about soy’s allergic potential,
mainly centered around the highly emotional discussion of whether it causes serious
health problems in babies who are fed soy infant formula. So let’s take a look at
that issue and see if we can sort out the truth from the fiction.
Soy infant formula and allergies
Of the top eight foods that cause 90% of food allergies, soy ranks last on the list.
Still, as a precaution, it is now being listed as an allergen on all products that
might contain it here in the US. You may have already seen “This product may
contain soy” on labels for everything from ice cream to margarine.
Severity of reactions to food allergens. Percentage of challenge-positive
patients vs. severity of elicited allergic reaction (number of food challenges).
— Adapted from Sicherer et al.
Several anti-soy groups have turned their focus onto soy infant formula, using people’s
emotions about infant health to make it a “hot button issue” and support a larger
case against soy. Among their arguments is the supposed potential for allergic response
in infants, leading to colic, gastrointestinal problems, “stunted growth,” or even
anaphylactic reactions. While any food has potential for causing an allergic reaction
(in adults as well as in babies), the truth is that soy is among the least likely
of several common foods to cause such serious responses. As you can see in the chart
above, when researchers looked at the incidence and severity of soy allergies, they
found people had much more severe and frequent allergic reactions to the proteins
found in cow milk than to the proteins in soy. In infants, only around 10% of those
who were allergic to cow milk were also allergic to soy formula.
I would also like to point out that babies have been fed soymilk for nearly a hundred
years, and as of today (aside from thyroid disease and the relatively rare, true
soy allergy), there simply are no data to support detrimental effects. In fact,
recent studies on the use of soy-based infant formulas indicate that soy proteins
do not have hormonal effects in long-term feeding, and that “isoflavones in soy
infant formulas do not adversely affect human growth, development or reproduction.”
Mother Nature so wisely designed breastfeeding to benefit our infants in every way,
helping them build a robust immune system and protecting them from allergies, sensitivities,
and digestive problems. Even so, we’re now learning that genistin, one of the most
common soy isoflavones, can help prevent and decrease severity of rotavirus infections,
a common gastrointestinal illness for infants, especially in poorer countries.
So while it’s true that soy protein can be allergenic, all food proteins
have this potential, so that’s not a good reason to eliminate soy as a viable substitute
for cow milk. In feeding our babies, I think everyone would agree these days that
breast milk is best. But when a baby cannot be breastfed, for whatever reason, soy
offers a reasonable alternative.
Choosing soy... or not!
If you don’t have a soy sensitivity or allergy, then whether you include soy in
your diet is simply a matter of personal preference. Soy foods such as tofu, soy
milk, and edamame can be delicious sources of beneficial soy proteins (see
our article on the health benefits
of soy for more nutritional information). You can also use supplements in
the form of bars or shakes, keeping in mind that whole bean products are best.
Obviously, if you do have a soy allergy, please do avoid soy, just as you
would any other allergen! But if you are sensitive to soy, rather than truly allergic,
it doesn’t mean you’re obligated to avoid it. When our patients report bloating,
gas, or other intestinal discomfort after eating soy foods, we advise them to try
a soy and yeast-free diet, colon cleanse, or
detox. You can also try limiting your intake to organic or non-GMO soy only,
or use only fermented soy products. Those with problems digesting beans will often
benefit from digestive enzymes and probiotics (such as Beano or the kind we offer
in our Personal Program), or by adding sea vegetables or digestive spices such as
ginger or cumin to their soy dishes. Or, maybe you decide that you just don’t want
to go to the trouble — and that’s okay! Your health is in your hands, and by listening
to your own wisdom, you can make decisions that are right for you.
Our Personal Program is a great place to start
The Personal Program promotes natural hormonal balance with nutritional supplements, our exclusive endocrine support formula, dietary and lifestyle guidance, and optional phone consultations with our Nurse–Educators. It is a convenient, at-home version of what we recommend to all our patients at the clinic.
If you have questions, don't hesitate to call us toll-free at 1-800-798-7902. We're here to listen and help.
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Related to this article:
References & further reading
on soy allergies and soy sensitivities
Original Publication Date: 04/28/2008
Last Modified:
08/21/2009
Principal Author: Dixie Mills, MD