More and more people are turning to plant-based or non-dairy milk, and soy milk (sometimes called soya milk) is a popular choice.
For most women, it’s fine to drink soy milk in moderation during pregnancy, and soy has many health benefits. A safe upper limit is approximately two cups of soy milk a day.
If you’re looking for a plant-based milk to drink instead of dairy, you may want to know about the benefits and possible risks so that you can make the best choice for you.
Soy contains phytoestrogens which for some people, may mimic the effects of the human hormone estrogen in the body.
We’ll look in detail at whether soy milk is safe or not, the health benefits, and any risks that you need to be aware of.
Is Soy Milk Safe During Pregnancy?
For most women, soy milk is safe during pregnancy, as long as it is part of a balanced diet (Source: NHS).
Registered Dietitian Eizabeth Somer is quoted as saying that “one to two servings a day” is appropriate – where one serving is one cup of soy milk (source: Parents).
Thickeners and Gums in Soy Milk
Just as with other products, when choosing a soy milk you should check the label and make sure you are drinking soy milk that is unsweetened and doesn’t have added artificial flavorings or thickeners such as carrageenan.
Carrageenan is a common food additive made from red seaweed. It is found in many dairy products like cottage cheese, cream and creamers, ice cream, and even some plant-based alternatives such as vegan cheeses, nondairy desserts, almond milk, and coconut milk.
Carrageenan is best avoided during pregnancy because it has been shown to lower glucose tolerance and increase resistance to insulin, therefore possibly contributing to the development of diabetes (Source: Springer).
Having said that, many manufacturers have phased out carrageenan and are using xanthan gum as a thickener.
Xanthan gum is used as a laxative as well as a way to lower blood sugar and cholesterol in people with diabetes (Source: AJCN).
Because not enough studies have been done on the safety of xanthan gum during pregnancy, it is best to consume small amounts.
Other Dietary Considerations of Soy Milk During Pregnancy
If you’re drinking soy milk as an alternative to cow’s milk, either through preference, a vegan diet, or because you have a food intolerance or allergy, you should ensure you’re still getting enough iodine in your diet.
Iodine is essential during pregnancy as it’s required for the development of your baby’s brain. Cow’s milk is a good source of iodine, whereas many non-dairy alternatives like soya milk are low in iodine (source: Cambridge University).
If you have hypothyroidism or have been diagnosed with breast cancer, you are advised to limit your intake of soy. This is because soy phytoestrogens may increase breast cancer cell growth in some women (Source: JON).
It is worth noting that if cholesterol levels are a concern for you, black soybeans – which are also used in black soy milk – can help lower cholesterol more than white or yellow soybeans.
Black soybeans, being higher in antioxidants, have also been shown to provide the greatest improvement in risk factors for cardiovascular disease (Source: NCBI).
Are There Benefits of Drinking Soy Milk During Pregnancy?
The first obvious benefit of drinking soy milk is that it is a source of protein that is low in fat.
Soy milk and other soy foods are rich in B vitamins which are very important if you are vegan or vegetarian.
Soy also contains fiber, magnesium and potassium. As far as protein goes, soy protein is a complete protein, which means that it contains all nine essential amino acids. 1 cup of soy milk contains 7g of protein (Source: HSPH).
Fortified soy milk during pregnancy can be a good source of vitamin B12, vitamin D, iron, and calcium (Source: MDPI).
If blood pressure is a concern for you, you may like to know that soy milk has been proven to lower blood pressure, particularly diastolic blood pressure.
Best results were seen for those with mild to moderate hypertension, compared to people who drank cow’s milk (Source: JN).
Is Almond or Soy Milk Better for Pregnant Women?
If you’re also interested in the benefits and safety of almond milk during pregnancy, we have an article covering all aspects of almond milk here.
Almond milk, like soy milk, often has added vitamin D and calcium and is a good vegan or vegetarian source of protein.
Soy milk is higher in calories (95 calories per cup) than almond milk (30-50 calories). So, if you’re watching your calorie intake, almond milk may be a better choice for you.
As mentioned above, soy milk is also higher in protein (7g of protein per cup) than almond milk (1g of protein per cup).
If you are vegan or vegetarian, soy milk will be a better source of protein, particularly as it is a complete protein, as we said above.
Soy milk is also slightly higher in carbohydrates than almond milk, yet lower in overall fats. Both have similar amounts of calcium and magnesium whereas soy milk has significantly more potassium and zinc (Source: EuropePMC).
However, many people prefer the taste of almond milk, and of course, it is important to take allergies into account. If you are allergic to soy or almonds, the choice is already made for you!
Is Soy Milk Pasteurized?
Most commercial soy milk has been pasteurized or treated with high temperatures to be able to be stored safely.
You can spot pasteurized soy milk by checking the packaging which should say UHT (ultra-high temperature).
You may come across another type of treatment for soy milk which is UHPH: ultra high-pressure homogenization.
This is another way of heat-treating soy milk, and provides the same long-term storage as UHT, with perhaps even better color stability (Source: ScienceDirect).
Some popular store brands of pasteurized soy milk that are safe during pregnancy include:
- Simple Truth Organic
- Trader Joe’s
- Dream Blends
- Pacific Foods
- 365 Everyday Value
- Nature’s Place
- Sunrich Naturals
- Rolling Hills Farm
When choosing your soy milk, remember to choose a brand that is unsweetened and that uses xanthan gum as a thickener rather than carrageenan.
Many brands are organic, which is always a plus as you want to avoid consuming pesticides if you don’t have to (source: CDC).
Several brands are fortified with extra vitamins and minerals, which you can use if you choose.
If you’re struggling to compare different store-bought soy milks, we’d suggest Silk Unsweetened Organic, WestSoy Unsweetened, and Maeil, as they’re not sweetened and aren’t thickened with carrageenan.
Can I Drink Homemade Soy Milk During Pregnancy?
If you want to go one step further and make your own soy milk, you can do that easily at home.
Soy milk is a good choice for cooking since it has a similar texture to cow’s milk. However, you do need to cook your milk before drinking it. Soy is a legume and shouldn’t be eaten uncooked or raw.
Here’s how you make your own soy milk:
- Soak a ½ cup of soybeans overnight in 1 cup of water.
- Drain the soybeans and slip off the outer skin with your fingers (optional, for better-tasting milk).
- Blend the soybeans with 3 cups water till as smooth as possible.
- Strain the result through a piece of cheesecloth, a nut bag, a fine mesh strainer, or similar.
- Pour the milk into a saucepan and add another cup of water. Bring to a boil and skim the foam off the top.
- Allow your milk to cook over medium heat for 20 minutes, stirring from time to time.
- Let your milk cool, then use as needed.
Optional extras: you can add cinnamon, a handful of dates (blend them in), or a dash of vanilla extract.
Your soy milk will keep in a glass jar in the refrigerator for 3-5 days. Always ensure you’re storing it properly, as homemade soy milk isn’t pasteurized. For more on food hygiene, you can see our tips here.
Note: you can freeze your soy milk if you wish. Pour it into ice cube trays and whenever you want soy milk for drinks or other recipes, you’ll have milk cubes on hand.
Should I Avoid Soy if I’m Having a Boy?
This is a controversial topic because there have been studies done on animals that were born with abnormalities after being exposed to soy isoflavones (Source: NCBI).
However, animals metabolize soy isoflavones differently than humans, and studies so far have not observed any significant long-term effects in babies fed soy formula (Source: NCBI).
The other concern is around boys born to pregnant women consuming soy having a higher risk of cryptorchidism (undescended testes) and hypospadias (changes in the position of the opening of the urethra in boys).
However, dietary phytoestrogens such as those present in soy have not been shown to increase the risk of either of these abnormalities (Source: EHP).
Another concern is whether soy formula can contribute to autism in baby boys. The concern has probably arisen around boys since autism is 4.7 times more prevalent in boys than in girls.
Current studies seem to show that the level of maternal thyroid hormones from insufficient dietary intake, consumption of flavonoids, as well as environmental factors may have a role to play in the incidence of autism (Source: ScienceDirect).
Because soy is a source of flavonoids, it is best to be cautious and not over consume soy as well as other legumes. As stated at the start of this article, the suggested maximum is two cups of soy milk a day.
There is some research that indicates that autistic children who are fed soy formula can have increased incidences of autistic behaviors (Source: NCBI).
In conclusion, soy milk is safe to drink for most women, as long as it is in moderation.
Soy milk can form part of a balanced diet, and in conjunction with other sources of protein – and even other plant-based kinds of milk.
This article has been reviewed and approved for publication in line with our editorial policy.