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What You Need to Know Before Giving Your Baby Soy Formula

Soy formula always used to taunt me. Obviously other parents were using it. What did they know about regular formula that I didn’t?

Oh my gosh!!


*breathing into paper bag* 

That panic attack seemed even stronger at 3 in the morning when I was trying to figure out what in the…um…heavenly-hosts was wrong with my screaming child. Was she allergic?  Should I switch to a soy baby formula too?

Or was I about to play a dangerous game of medical roulette?

You see, there’s a lively debate going on right now about soy formula, with two camps fighting back and forth. (I call them the “No-Soy Camp” and the “Go-Soy Camp.”) I’m actually not in either camp. (I hate camping.) Instead, I’m going to present their reasoning and let you decide which side of the river to pitch your tent.

Think of this as a “Choose Your Own Adventure” style of article. Ready for your first chapter?

Does Soy Formula Cause
Early Onset Puberty?

Soy formula is made out of soybeans. (I know. Shocking. Better call CNN.)

Soybeans contain phytoestrogens, which have been shown to mimic estrogen in the body. Having too much estrogen, some experts say, can cause puberty to start early in some kids. (Something that’s becoming more and more common.)

Here is what both camps shout about this issue:

The No-Soy Camp: Soy Formula Causes Early Puberty

Since a baby’s diet is almost 100% formula (or breastmilk), this means the a soy formula fed baby is getting exposed to a lot more of those phytoestrogens than toddlers or adults who have a more varied diet.

There are several studies that indicate there may be a link between soy formula and early puberty.

  • In the first study, they found that 2-year old girls who were fed soy formula had more breast tissue than their non-soy fed sisters.
  • This study demonstrated that “an association between early soy exposure and early menarche [menstruation] is biologically plausible.” 
  • Another piece of research showed that adult women who were fed soy formula as infants had longer and more severe periods than those women who were fed diary-based formulas as babies.

The American Association of Pediatrics issued a document that recommended parents only choose soy formula if…

  • The family is strict vegan
  • The infant has congenital galctosemia
  • The infant has been diagnosed as being lactose intolerant.

So what does the Go-Soy Camp say about all this?

The Go-Soy Camp: Potential Cost is Worth the Benefit

Firstly, they say, there are a LOT of factors that affect puberty later in life. “Plausible” is not the same as “Definite.” They also like this University of PA Study that disagreed with the “early onset” claim. (Although it did replicate the charge that soy-fed babies grew up to be women who had longer and more intense menstrual cycles.)

For babies who are extremely gassy and colicky, they say, and are lactose intolerant, soy formula is a good solution.

Does Soy Formula Cause ADHD?

Another point of controversy linked to soy formula is the issue of ADHD.  Soy formulas have very high levels of manganese (about 80-times that of breast milk.) Combine that to the whole “100% of a babies diet is formula” thing and there may be room for concern.

Manganese is a critical nutrient to healthy growth, but like buttercream frosting, too much of a good thing has consequences.  Consequences like learning disabilities.

The No-Soy Camp: Not Worth the Risk

Using this report as an example, No-Soyers note that rats given high levels of manganese had a harder time concentrating on the same tasks their non-soy formula friends were given. The low-dopamine levels caused by the manganese (one of the factors of ADHD) were clearly demonstrated. This seems to have been upheld by a study published in Neurotoxicology.

The Go-Soy Camp: No Causal Chain

At this point in the argument, Go-Soy Defenders will jump in to remind you that although soy formula has more manganese than human milk, it still falls into the safe daily suggested intake for infants.

They also would point out that in this study, the scientist admitted that although it is “highly suggestive” there’s a link between soy-based formula and ADHD, “no causal chain linking Mn ingestion, Mn absorption, neurotoxic damage and behavioral deficit” has been irrefutably demonstrated.

In other words, although it may be “plausible” it’s still not “definite”.

What’s a Parent to Do?

Well, the first thing you should do is sit down and talk with your doctor about it. He will know if there have been new published research that I’m missing here.

The second thing you’ll need to do is to make sure you’ve got your terms right. For example, many parents will choose a soy formula because they mistakenly think their child has an allergy to cow’s milk. 

Medical studies (on both the go- and no-soy side) have shown that babies with milk allergies usually have the same issues with soy as well. Soy formula is recommended for babies that have shown they are lactose intolerance through testing. That is NOT the same as a milk allergy.

Many doctors will recommend trying one of these options first, before switching to a soy formula.

Even with these specialties, you may decide that it’s time to head over to the “Go Soy” Formula Camp. Here are several of the best brands to start with. (Buy in bulk, you’ll save a TON of money that way!)

Have You Read These Yet?


Why Kids Are Hitting Puberty Earlier Than Ever. USNews.com
Early Life Soy Exposure and Age at Menarche. NIH.gov
Breast Development in the First 2 Years of Life: An Association with Soy-Based Infant Formulas. NIH.gov
Exposure to Soy-Based Formula in Infancy and Endrocinological and Reproductive Outcomes in Young Adulthood. JAMANetwork.com
Phytoestrogens in Soy-Based Infant Foods: Concentrations, Daily Intake, and Possibly Biological Effects.SagePub.com
Study: Soy Formula is Safe. ABCNews.com
Use of Soy Protein-Based Formulas in Infant Feeding. AAPPublications.org

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36 thoughts on “What You Need to Know Before Giving Your Baby Soy Formula

  1. Karla,

    I’m so sorry your grand baby is having tummy troubles. It might be worth another switch if it seems that the soy isn’t setting with her. Take a look at this article about how to make the switch. Also, it’s important to try a formula out for a week (if you can) before deciding whether or not it’s a good fit. This article, with a list of all the major brands of formula, might be a good place to start your research. Also, I would recommend trying probiotics with her since that can help with constipation problems. This article about constipation is a good resource too.

  2. I have a 3 week old grandbaby and since she been borne she’s been constipated the doctor done switch her milk three times so finally she switched her to Enfamil soy and shes no longer constipated but it seems as if the milk is hurting her stomach when she have a bm she crys like its hurting her stomach. Now im confused. Need some answers.

  3. Oh friend, what a nightmare you’re dealing with! In regards to the soy, don’t worry too much…it’s only temporary. Once her other digestive issues have improved and her system has gotten a little older, you’ll be able to change things up. I was going to encourage you to talk to your doctor about the Prilosec, so I’m glad to hear he/she suggested that. I would ask the doctor for a referral to a pediatric gastrointerologist. In other words, a doctor who’s only job is to research and know everything there is to know about the digestive system of children. That’s the next steps I would recommend.

    (Also, did you read Chelsea’s story? That may encourage you – other moms have walked this path and found improvement! You will get there, too.

  4. Help! My 10 week old daughter has been a fussy baby since birth. She was originally on Similac Advance and just was never settled or content. She would kick her legs and flail her arms all day long. She never fell asleep to a bottle and rarely slept. She would try to jump off of me when trying to burp her. Silent reflux seemed to be an issue as well. She also had mucus in her stool and very gassy. She was then switched to Similac Sensitive…same issues and she wanted to eat more frequently. Like constantly!!! Because of the mucus and what seemed to be baby acne and red diaper area, she was switched to Similac Alimentum. The doctors also out her on zantac. She finally fell asleep to a bottle!!! Mucus went away. Reflux did not. They increased zantac but reflux never went away. So as parents, we decided to stop zantac as it wasn’t doing any good and seemed to cause painful gas and belly pain! And the zantac caused her to have bowel movements three times a day…very foul smelling including the gas! She was starting to sleep a little at night and be more content when awake but still fussy and not completely happy. We went to her 2 month checkup, and the Dr said her stomach looks distended and her stools seem watery and still having issues with reflux. She said to increase zantac and against my better judgment, I started her back on the medicine while still keeping her on the alimentum. Then, we had the worst two days. Our 10 week old daughter only slept for 4 hours out of a 24 hr period and screamed an ear piercing cry all day long. Nothing helped but when drinking a bottle. She stiffened up straight as a board and passed gas all early long. Next day, she slept only 5 hrs out of 24 hour period. She would only sleep for 20 minutes and then something would wake her up and she would scream like we never heard before. We stopped the zantac and called the doctor. She said she would get prilosec approved and to switch to soy right away. I really didn’t want to switch to soy but I did because my daughter was in intense pain and I do not know why. She has only been on the soy for two days so I am not sure if it is helping yet. She is constipated for the first time ever however! Any advice on what I should do next? I really don’t want her on the soy. I just don’t know what to do or where to turn to next. Please help!!!

  5. Tiffany,

    Thanks for sharing your experience! I’m so glad you were able to find a formula for your little one that is working so well!

  6. My baby had bad colic in the begining i used two diff bottles the glass phillips Avent and the glass dr browns.I found when i would use the Avent bottle she would cry more after and spit up more so i stopped using that bottle and just went with the dr brown and that helped bigtime!Also the first formula i gave her was earths best organic formula amd it made her so sick! I did my research and found that the DHA thats in it is extracted by a chemical called hexaine! So i did more reasearch and heard amazing things about Hipp organic formula from the UK so i ordered it online from torafoods.com and it worked great for my baby! She instantly got waay better and make sure you get a good burp out of your baby it helps too.All i can say is formulas from the Uk Hipp organic or Holle organic is the best n the cleanest of them all im from canada and i will be using hipp from the Uk on my baby and my next for sure!

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