Soy formula became available in the United States in 1929, or perhaps even earlier. It was invented for those infants who were “allergic” to cow’s milk. (Not cow’s-milk-based formula.) About 12% of the formula sales in the United States are for soy-based formula.
Soy formula contains 4,500 times — or more — the level of phytoestrogens found in cow’s milk or in human milk. Yet, for many parents and healthcare providers, soy milk is often the default for breastfed infants. That’s unfortunate, since soy formula is associated with several potential risks.
Soy is a potent endocrine disruptor
Soy milk contains phytoestrogens, that is, plant estrogens. So, whether a substance is an animal-based estrogen or a plant-based estrogen, the effect of the substance can affect endocrine function.
There’s good science that phytoestrogens are potent endocrine disruptors. For example, a high level of phytoestrogens can disrupted the thyroid.
Soy formula may cause infants to be constipated
My earlier guest, Dr. Bryan Vartabedian, didn’t cite published research, but as pediatric gastroenterologist with decades of experience, he qualifies as an expert. In his book, Looking Out for Number 2, he says, “The most constipating formula is soy.” (Page 212.)
Other adverse effects of soy milk on children are uncertain
We’ve all heard or read claims that soy milk “causes” all sorts of “dangers”. In truth, cause-and-effect is hard to prove, and “danger” is an inexact term. Nonetheless, there is no shortage of these stories on the Internet; one article listed as many as 170 “dangers” of soy formula. Some articles quote research studies, but their overall conclusions are often exaggerated or distorted. That being said, we still need to be concerned about with soy formula.
What’s the relationship between soy formula and early onset of menses?
Research has begun to show that there’s a possible link between early consumption of soy and earlier onset of menses. (And you may recall that in an earlier podcast, Donna Walls mentioned a soy formula-fed infant who began her menses at age six.)
We are a long way from casually concluding that there’s a cause-and-effect relationship between early soy consumption and early onset of menses. In fact, we need more studies before we can even be sure of an association. But because soy is an endocrine disruptor, we need to be aware of the potential consequences of feeding soy-based formula to infants.
What’s the relationship between soy formula and adult health?
Maybe you’ve made the casual observation that adult women who have uterine fibroids have been fed soy formula as infants. Research has shown that Eker rats who have consumed soy are more likely to develop uterine fibroids.
Animal studies have also shown a correlation between soy consumption and other adult-onset problems, including breast cancer, brain cancer, and prostate cancer. Can we extrapolate research results in animal studies to humans? No. But these animal studies are, as Dr. Patisaul explained in our interview, “unsettling.”
The AAP says soy formula gives “no advantage”
Interestingly, in 2008, the American Academy of Pediatrics (AAP) clearly stated, “Isolated soy protein-based formula has no advantage over cow milk protein-based formula as a supplement for the breastfed infant…” In that statement, the AAP insists that there is no evidence to support the use of soy milk in these situations.
Yet, in my experience, it is often the default for babies who are “allergic” to cow’s milk, “fussy” or “colicky.”
Think about it. Ten years after the AAP issued that statement, we still have 12% of infants being fed soy formula. Why?
Last thoughts about the risks of soy formula
Occasionally, I enjoy my soy-based drink or munch on my edamame beans. I will continue to do so. But I would give a stern warning to anyone who is supplementing their infant’s diet with soy formula or, worse yet, giving soy formula as the sole source of nutrition for one year.
And everyone should be paying attention to the “sole source” issue.
During my recent podcast with Heather Patisaul, she summed up her thoughts well. She said exactly what the AAP has said: There is no advantage for soy-based formula for infants. I completely agree.
Is there a better option for galactesemia babies? I know they are by far the rare exception, but was curious?
Probably not. I say “probably” because there are, technically, different types of galactosemia. But most commonly, the baby with galactosemia would have the “classic” form. That basically means that he has a metabolic condition where he cannot break down the lactose that is in milk. (And this should NOT be confused with lactose intolerance, that’s a totally different thing!) But if you’re asking, is there a better alternative than soy? YES! Most certainly! There are at least two different brands of infant formulas that I’m aware of which are made specifically for the baby with galactosemia. If you or someone you know has a baby with galactosemia, you should definitely ask many questions to your friendly neighborhood registered dietitian. If she knows anything about infants, she, along with your pediatrician and endocrine specialist would be able to give you advice. (So I’m not giving you medical advice, I’m just saying, get the exact facts about the baby’s condition, and be sure that you ask plenty of questions about what the feeding options are available, and what is best in that situation.)
Pediac recommended soy formula Similac Isomil for 2 weels for my 1 month old baby…is it safe?
I’m not qualified to determine if that is or isn’t best for your baby. It’s entirely possible that your pediatrician has a very sound reason for recommending this soy-based formula for a 2-week old. So you need to ask yourself (or better yet, ask him!) what the rationale was for suggesting soy. The American Academy of Pediatrics originally wrote their statement on soy formula in 1999, and then revised as found here. Note they say, “This report reviews the limited indications and contraindications of soy formulas. So if there are “limited” indications, you’ll need to see if your pediatrician had identified one of those “limited” indications in your baby. You should, however, also listen to my podcast on this topic with Heather Patisaul (link is in the blog post you just responded to.)
We were duped in the 1990’s to believe that soy was good for us; hence, soy infant formula seemed like a good choice. Worse yet, after soy infant formula, many toddlers were then put on soy milk. There is plenty of theories out there about what soy infant formula and soy milk can do to girls; but little is written about the effects on boys. No one has any idea what this toxic crap is doing to our children. Many children — perhaps their height was stunted, but a correlation to soy was never connected. I am sickened that this product is even on the grocery store shelves. There should be warning labels on ALL soy products saying that they contain an extremely high phytoestrogen content. If I could have seen a label like that, I would NEVER have purchased this toxic crap! I am upset every day that I bought this horrible product for my children to consume. It makes me sick! And there is NO reason why this horrible product should not be labeled. The public is being duped. I regret every day that I allowed my children to drink that garbage. I had no idea about phytoestrogens content back then. And now there is nothing I can do to change it. All I do is worry about this sickening product and what it might have done to my children. The FDA does little to warn people about this — look at the myplate.gov and you will see that Soy Milk is listed as an alternative to dairy milk — with absolutely NO WARNING about the phytoestrogens. Our children should be protected from this crap; and it is still on the market !!! Disgusting!
So you probably know that I agree with everything you just said! It’s pretty incredible that you buy some herbal tea for your sore throat and there’s all this baloney on the box that says that these claims have not been approved by the FDA, blah blah blah. BUT where it comes to formula, there are no warnings whatsoever. Oh, don’t get me going!
As related to your own children, and your decisions. In my 40-something years in nursing there’s one thing I’ve had to learn, over and over. First, both parents and providers make decisions with only a fraction of the information they need in order to make a decision about their health or someone else’s. On the whole, I’ve done pretty well for myself, my family, and my patients. But I’ve made some mis-steps. But I reassure myself that I tried; I thought; I did the best I could with the information I had. Most of us, who are conscientious and caring, do that. I’m thinking that might describe you, too.