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Enfamil Soy vs Similac Soy – Differences & Which Is Best In 2024

Formula feeding can be trickier than expected if your baby is lactose intolerant, has a cow’s milk protein allergy or they suffer from colic and reflux.

Standard formula made with cow’s milk is not suitable for all babies and can make babies with allergies and intolerances unwell. So, what can bottle-feeding parents use instead of standard formula?

Soy formula milk is one of the most popular alternatives to standard formula milk and the two most popular brands are Enfamil Soy and Similac Soy. Are you thinking about switching to soy formula milk but want to know which is best?

We compare Enfamil Soy and Similac Soy in this article, covering the differences and revealing which soy formula milk is the best in 2024.

What Is Soy Baby Formula?

Soy baby formula is formula milk made from soybeans. All formula milk, dairy-free, hypoallergenic, and standard cow’s milk formula, must all meet specific criteria regarding their nutrient content, composition, and purity.

Soy formula milk contains the same calories and important nutrients as a standard formula. Despite what some parents may fear, babies who are fed soy formula milk can be as healthy and grow and develop at the same rate as babies who are fed cow’s milk formula. 

Why Would A Baby Need Soy Formula?

As standard, the majority of first-time bottle-feeding parents will start with feeding their baby standard formula milk. However, there are several reasons why parents may choose to switch to soy formula. 


Vegan parents may not want to feed their baby standard formula as it goes against their own moral and ethical values.

If you do not want to feed your baby any food or drink made with animal products, you will need to avoid standard formula as it contains cow’s milk protein.

Vegan families may decide to feed their baby soy formula as it is a safe alternative to the standard cow’s milk formula. 

Conscious of the environment

Parents who are conscious of the impact cattle farming has on the environment may choose to not feed their baby cow’s milk formula. If you are looking for dairy-free formula milk so you can respect your feelings about the environment then soy formula milk is an option.

Lactose intolerance

What Happens If My Baby or Toddler Drinks Spoiled Milk?

If your baby has lactose intolerance it is unlikely they will be able to drink standard formula without experiencing unpleasant symptoms.

If your baby is lactose intolerant they may experience the following symptoms after consuming dairy products – diarrhea; bloating; gas; painful stomach cramps.

What Is Lactose Intolerance

Lactose intolerance is caused when the digestive system can’t break down lactose – the sugar found in dairy products – and your baby may suffer from the symptoms if they drink standard formula milk.

Soy milk does not contain dairy and, therefore, will not upset your baby’s tummy. 

Cow’s milk protein allergy

Babies who are allergic to dairy, particularly the cow’s milk protein used in standard formula milk, may be fed soy formula to prevent an allergic reaction.

Food allergies are common but can still be dangerous and it is always best to avoid feeding your baby anything containing ingredients they are allergic to, no matter how small the amount.

To help reduce colic

Dairy products can play havoc on the digestive systems of both adults and babies.

If your baby is experiencing a lot of tummy pain, trapped gas, and bloating, accompanied by periods of prolonged crying then they may be suffering from colic.

Some parents choose to switch their baby to a soy-based formula to help relieve their baby’s colic symptoms; soy milk does not have as much gas as cow’s milk.

Enfamil Soy vs Similac Soy Isomil – Which Is Best in 2021?

If you are formula feeding your baby you are sure to have heard of Enfamil and Similac. Both these companies offer a dairy-free formula option for baby’s who cannot drink regular formula made with cow’s milk protein.

Enfamil Soy ProSobee and Similac Soy Isomil are both soy-based baby formula milk and whilst they are both suitable for a dairy-free diet, there are some differences between the two. 

Before deciding which soy-based baby formula is the best, let’s take a closer look at the pros and cons of Enfamil soy and Similac soy dairy-free milk. Keep reading to the end of this article to find out which soy formula is best, Enfamil ProSobee or Similac Isomil. 

Enfamil Soy Review 

Enfamil ProSobee infant formula is soy-based, dairy-free formula milk produced by Mead Johnson and sold by the Enfamil formula company. Enfamil ProSobee is made with plant-sourced protein instead of cow’s milk protein.

Soy protein is kinder on sensitive tummies and Enfamil ProSobee claims to help reduce fussiness caused by painful gas and stomach upsets often associated with cow’s milk formula. 

Enfamil is the number one pediatrician-recommended baby formula brand and their ProSobee soy-based formula is popular amongst parents needing a dairy-free alternative to regular formula milk. 

Enfamil soy formula contains the same amount of  DHA (Docosahexaenoic acid, an omega-3 fatty acid) as regular formula milk and therefore offers the same level of brain nourishment. It is also rich in the following nutrients:

  • Choline
  • Calcium
  • Iron

As we previously mentioned, dairy-free and plant-based formulas have to reach the same nutrient, composition, and purity criteria as routine formula milk. Enfamil ProSobee is full of everything your baby needs to grow and develop healthily, as well as being dairy, milk, and lactose-free.

Here is a list of all the ingredients in the Enfamil ProSobee soy formula: 

  • Corn Syrup Solids (54%)
  • Vegetable Oil (26%) (Palm Olein, Coconut, Soy, and High Oleic Sunflower Oils),
  • Soy Protein Isolate (14%)
  •  Calcium Phosphate
  • Potassium Chloride
  • Sodium Citrate
  • Calcium Carbonate
  • Magnesium Chloride
  • Magnesium Phosphate
  • Potassium Citrate
  • Ferrous Sulfate
  • Zinc Sulfate
  • Cupric Sulfate
  • Potassium Iodide
  • Sodium Selenite
  • Mortierella Alpina Oil (Source of Arachidonic Acid [ARA])
  • Crypthecodinium cohnii Oil (a Source of Docosahexaenoic Acid [DHA])
  • L-Methionine
  • Choline Chloride
  • Ascorbic Acid
  • Niacinamide
  • Calcium Pantothenate
  • Vitamin D3
  • Riboflavin
  • Thiamin Hydrochloride
  • Vitamin B6 Hydrochloride
  • Folic Acid
  • Vitamin K1
  • Biotin
  • Vitamin B12
  • Inositol, Taurine
  • Vitamin 3 Acetate
  • L-Carnitine
  • Vitamin A
  • Palmitate

Pros and Cons of Enfamil Soy Formula

Enfamil ProSobee is a popular dairy-free formula used by families across the US. However, it is always important to know the pros and cons of a baby formula milk before feeding it to your baby. 

Let’s take a close look at the pros and cons of the Enfamil ProSobee soy formula. 


  • Enfamil ProSobee is milk-free, lactose-free, and dairy-free. The absence of these ingredients makes Enfamil ProSobee a great option for babies who suffer from lactose intolerance.
  • Contains DHA for proper brain development.
  • Claims to reduce fussiness and crying by preventing tummy pain caused by the excess gas in cow’s milk protein.
  • Offers complete nutrition for babies between the ages of 0 – 12 months.
  • Enfamil is the number one infant formula recommended by pediatricians.
  • Available in powder, ready to feed liquid and concentrated liquid form.
  • More affordable than other plant-based infant formula milk.


  • Enfamil Soy formula has an unusual taste that many babies dislike.
  • High corn syrup content.
  • Contains palm oil which may not align with the environmental values of some parents.
  • Not always well-stocked online.
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Similac Soy Isomil Review 

Similac Soy Isomil Infant Formula with Iron, Powder, 30.8 oz (Pack of 4)

Similac Soy Isomil is a nutritionally complete, easy-to-digest, soy-based formula for babies who suffer from fussiness and gas.

Similac Isomil is the only soy formula clinically proven to help support a baby’s developing immune system, thanks to the inclusion of the prebiotic FOS (fructooligosaccharides).

Similac Isomil is specially designed for babies with lactose intolerance and galactosemia, a rare hereditary disorder of the carbohydrate metabolism that affects the body’s ability to convert galactose to glucose.

Isomil is gentle on your baby’s digestive system and doesn’t cause the painful gas and bloating that can be caused by lactose intolerance. 

Similac Soy Isomil is also rich in OptiGRO, which is a special mix of DHA, Vitamin E, and Lutein. These components have the following benefits:

  1. DHA is important for brain development.
  2. Vitamin E is important for cell development.
  3. Lutein has similar nutrients to those found in breast milk and is needed for eye health.

Similac Isomil also contains:

  • Nucleotides for the improvement of the immune system
  • Antioxidants for cell protection
  • Prebiotics for maintaining a good digestive system and improving the immune system.

Similac Isomil tastes better than another plant-based infant formula as it contains added sugar. This may be off-putting for parents who do not want their baby consuming too much sugar.

Considering how much formula milk a baby drinks in their first year it is understandable that some parents may not be comfortable with giving their baby a formula that has high sugar levels. 

Here is a list of all the ingredients in the Similac Isomil Soy formula: 

  • Corn Syrup Solids (40%)
  • Soy Protein Isolate (15%)
  • High Oleic Safflower Oil (11%)
  • Sugar (10%)
  • Soy Oil (8%)
  • Coconut Oil (8%)
  • C. cohnii Oil
  • M. Alpina Oil
  • Beta-Carotene
  • Lutein
  • Short-chain Fructooligosaccharides
  • Calcium Phosphate
  • Potassium Citrate
  • Potassium Chloride
  • Salt
  • Magnesium Chloride
  • L-Methionine
  • Ascorbic Acid
  • Choline Chloride
  • Potassium Hydroxide
  • Taurine
  • Ascorbyl Palmitate
  • Ferrous Sulfate
  • Inositol
  • Zinc Sulfate
  • Mixed Tocopherols
  • L-Carnitine, Niacinamide
  • d-Alpha-Tocopheryl Acetate
  • Calcium Pantothenate
  • Copper Sulfate,
  • Thiamine Hydrochloride
  • Vitamin A Palmitate
  • Riboflavin
  • Pyridoxine Hydrochloride
  • Folic Acid
  • Potassium Iodide
  • Phylloquinone
  • Biotin
  • Sodium Selenate
  • Vitamin D3
  • Vitamin B12
  • Lycopene

Pros and Cons of Similac Soy Formula

Similar to Enfamil ProSobee, there are both pros and cons to feeding your baby Similac Isomil. Let’s delve into the pros and cons of Similac Isomil infant formula.


  • Tastes better than other soy formula milk due to the added sugar.
  • Contains a unique blend of Lutein, Vitamin E, and DHA, nutrients that have several health benefits.
  • The number one formula brand trusted by moms (according to formula sales figures as of 06/2020).
  • Easy to digest.
  • Eases colic pain and soothes sensitive tummies.
  • Suitable for babies following a vegetarian diet.


  • It is not budget-friendly.
  • It has a strong smell which may be off-putting to some babies.
  • Contains high levels of sugar.
  • May cause constipation
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Differences Between Enfamil Soy and Similac Soy Isomil 

Now you have read our reviews of both Enfamil soy and Similac soy formula, let’s delve a little deeper and compare the two. 

The main differences between Enfamil ProSobee and Similac Isomil are: 


Soy formula milk is known to not taste as pleasant as standard cow’s milk formula. However, out of the two, Similac is thought to taste better as it has added sugar. Enfamil ProSobee uses corn syrup and palm olein to try and improve its taste but Similac seems to be enjoyed more by babies. 

Sugar content

Similac Isomil has added sugar to improve the taste of its soy-based formula but this can be problematic for babies who struggle to digest sugar. Enfamil ProSobee is made with corn syrup and no added sugar and this may make it the kinder option for your baby’s tummy. 


Similac Isomil soy formula is more expensive than Enfamil ProSobee. A 12.9oz can of Enfamil ProSobee powder formula currently costs $21.99 when bought from the Enfamil website.

In comparison, if you purchase Similac Isomil from the Similac website you will have to pay $133.19 for a case of 4 30.8oz cans (which is around $33 a can). 


soy milk

Whilst both formulas are made from soy-based protein, there are a few different ingredients that make each formula unique. Similac has a blend of lutein, DHA, and vitamin E; lutein is a nutrient also found in breastmilk but is not included in the ingredients for Enfamil ProSobee. 

The Winner Is…

Both Similac Isomil and Enfamil ProSobee are suitable for babies who suffer from colic, allergies, lactose intolerance and are following a vegetarian or Kosher diet.

If price is not an issue for you, the key difference between Similac and Enfamil is the sugar content. Sugar in Isomil helps it taste better but can cause problems for babies who struggle to digest sugar.

Enfamil may not taste as nice but it is more gentle and easy to digest for babies who do not react well to consuming a lot of sugar. 

Taking all this into consideration it is still extremely difficult to declare one better than the other. But if you are looking for lactose-free soy milk that is a little more budget-friendly then Enfamil ProSobee has to be the winner. It also contains less sugar which is always a good thing.


Is soy formula bad for babies?

Soy formula milk is not bad for babies but it is recommended that premature babies are not fed soy formula. However, if your baby was born on time and is healthy, soy formula can offer them full nutrition during their first year, just the same as standard infant formula.

What are the side effects of soy formula?

If you decide to feed your baby soy formula you may notice some side effects such as hives; eczema; coughing; digestive issues, vomiting, or diarrhea.

Why is soy formula bad?

Soy formula isn’t a good choice for all babies. This is due to the fact that soy formula has a higher aluminum content which can cause weaker bones in babies born pre-term.

The Final Thought 

Enfamil soy and Similac soy formula milk both offer your baby complete nutrition if you are looking for formula milk that doesn’t use cow’s milk protein.

Both Isomil and ProSobee are gentle on your baby’s digestive system and claim to help soothe gassy tummies, reduce fussiness, and prevent the symptoms of colic. 

As for which is the best, it will depend on your baby and how sensitive their stomach actually is. Enfamil ProSobee uses more corn syrup than Similac Isomil but the latter also includes added sugar.

If your baby has a difficult time digesting high levels of sugar, Similac Isomil may not be your best option. However, if your baby can’t tolerate the taste of Enfamil ProSobee and their digestive system seems a bit more robust, you may find Similac does actually work best for your little one. 

Every baby is different and each family has its own reasons for opting to feed their baby soy formula milk. Whether you choose Enfamil or Similac, they are two of the best soy-based formulas on the market in 2024 and will offer your baby all the nutrition they need to grow and thrive. 

If you want to have a better overall view of the types of formula that both these brands produce check out our article Enfamil vs Similac – which formula is best for your baby in 2024.