False Facts About Soy Milk Debunked

Historically, cow's milk has been the go-to choice for many Americans. But today, habits appear to be shifting away from dairy and towards plant-based milk choices. Back in 2010, for example, research suggested that one in five U.S. households opted for plant-based milk options, but by the end of 2023, this had risen to one in three. This is for a few reasons, but many people see dairy-free options as a more environmentally-friendly option than cow's milk, for example. While a number of people choose to drink oat milk, almond milk, or coconut milk, soy milk is also a popular dairy-free choice.

Soy milk, which is, of course, made with soybeans, has been consumed around the world for centuries. It was first developed in ancient China, and it is still a staple in the country today. In the early 1900s, it was mass-produced for the first time in France, and the market has continued to grow globally since.

But not everyone is a fan of soy milk, and this is largely because the beverage has been the subject of many myths and false facts over the years. Some believe drinking it will result in undesirable physical effects in men, for example, while others are worried about increasing their risk of disease. But actually, it turns out, for many people, soy milk is a safe, nutritious drink choice that may even help reduce the risk of cancer and dementia. For more, find some of the most common false facts about soy milk below, debunked.

Like all soy products, soy milk contains isoflavones. These are a type of plant-based compound called phytoestrogens, and they have similar properties to estrogen. This is the female sex hormone that plays a key role in everything from breast development to pregnancy to menstruation. Research suggests that in high amounts, estrogen may contribute to an increased risk of breast cancer. This is why, in recent years, there have been some concerns that the isoflavones in soy could raise the risk, too. But actually, this likely isn't the case.

Isoflavones might be similar to estrogen, but crucially, they are not actually estrogen. They behave differently in our bodies, and for that reason, multiple studies have confirmed that consuming soy products is unlikely to increase the risk of breast cancer. Confirmed risk factors for breast cancer include things like excessive alcohol consumption, genetics, dense breast tissue, diabetes, obesity, smoking, and getting older — not soy milk.

In fact, there is research to suggest that consuming a lot of soy may actually reduce the risk of breast cancer. In Asian cultures, for example, where lifetime soy consumption is higher, the risk of breast cancer appears to be lower. This could be to do with the isoflavones themselves, and their role in reducing inflammation and oxidative stress in the body. There is also some research to suggest that isoflavones may bind to estrogen receptors in the body and, in turn, help to suppress tumor growth.

Another pervasive myth around soy and soy milk is that drinking it will cause men to grow breasts. Again, this comes down to its isoflavone content. As we mentioned earlier, they have similar properties to estrogen, and estrogen is responsible for breast growth. However, there is very little research to suggest that drinking soy milk will cause men to grow breasts — or, to use medical terms, lead to gynecomastia (an increase in breast tissue).

In 2024, David Jenkins, a nutritional science and medicine professor at the University of Toronto, told The Washington Post that he had not seen any data to confirm that soy milk consumption would lead to "feminization in men." He also pointed out that no major health organizations warn against the consumption of soy milk for this reason. The fears around soy milk and breasts seem to stem from two studies, one of which was published in 2008, and described a 60-year-old man presenting with gynecomastia. This was an unusual and isolated case, and researchers suspected it could be due to the fact he was drinking almost a gallon of soy milk a day.

Most people do not drink anywhere near this much of any milk product, including soy milk, in a single day. Donald Hensrud, a professor of nutrition and preventive medicine at the Mayo Clinic College of Medicine, confirmed to The Washington Post that this study was "not representative of the overall evidence on soy phytoestrogens."

Many recipes, from baked goods to creamy sauces, call for cow's milk. But this doesn't mean that you can't swap in non-dairy alternatives, like soy, and get the same results. In fact, all dairy-free milks can be swapped 1-for-1 in recipes without affecting the quality of the end product. It might be made in a different way, but soy milk has a very similar texture and consistency to cow's milk. This is achieved by soaking soybeans in water, grinding them, boiling them, and straining them, before blending them all together to achieve a cow's milk-like liquid.

There are many soy milk products on the market from leading brands like Silk, for example, and all are versatile and easy to cook with. You can use them to make everything from creamy hot chocolate to velvety carbonara sauce to your favorite breakfast pancakes. And that's not all, soy milk can also help you make creamy plant-based mayonnaise without eggs, thick and comforting mac and cheese, and silky cauliflower potato soup.

Before you start cooking with soy milk, however, there is one thing you need to keep in mind, and that's to ensure you're using the right variety. If you use sweetened soy milk in a savory recipe, it might leave you with a dish that tastes a little too sugary. Sweetened soy milk is best saved for milkshakes and smoothies, for example, while unsweetened is ideal for savory dishes.

Hypothyroidism, also known as an underactive thyroid, is a condition where the thyroid gland (a small gland in the neck) does not produce enough hormones, leading sufferers to feel symptoms like tiredness, depression, cold sensitivity, muscle cramps, and tingling fingers. Although some of the symptoms can overlap, hypothyroidism is different to hyperthyroidism, which is an overactive thyroid. Research suggests that hypothyroidism is common in the U.S., and likely affects around five in every 100 people in the country.

In the past, experts were concerned that soy consumption could lead to hypothyroidism by potentially enlarging the thyroid gland and interfering with hormone production, but research now confirms this is likely not true. Hypothyroidism is often caused by an autoimmune disease called Hashimoto's disease. In some cases, it can also be caused by iodine deficiency or problems with the pituitary gland.

Research suggests that people with hypothyroidism can consume soy safely, but there are some things to consider. Soy may inhibit the absorption of an important medication for hypothyroidism, which is called levothyroxine. For that reason, people with the condition should try to avoid consuming soy milk or soy products around the time that they take their medication, and should wait a few hours after taking it before eating or drinking soy.

Cow's milk, of course, contains calcium. In 1 cup, there are around 300 milligrams of calcium, which is a good portion of the recommended daily intake (which is about 1,000 milligrams for adults aged between 19 and 50 years old). It's important that we all get enough calcium, because it helps with several functions in the body. It helps to keep our bones, teeth, and muscles healthy, for example, and it supports blood clotting, too.

Getting enough calcium can also reduce the risk of chronic diseases. In 2025, one January study suggested that consuming an extra 300 milligrams of calcium per day could potentially help reduce the risk of bowel cancer by as much as 17%. But cow's milk is far from the only source of this important nutrient. Other key sources of calcium include leafy greens, like kale and spinach, almonds, tofu, and, you guessed it, soy milk.

In fact, many fortified soy milk products have the same amount of calcium as cow's milk, with 1 cup boasting around 300 milligrams of the nutrient. This makes it nutritionally comparable to its dairy counterpart. Both almond milk and oat milk are also good sources of calcium, but soy milk has the most protein, with around 6 grams per cup. Soy milk also often has nutrients that cow's milk doesn't have, like fiber, for example, which is only found in plant-based foods.

Dairy might be the traditional milk choice for children (Got Milk, anyone?), but it's not suitable for everyone. In fact, research suggests that nearly 2% of children in the U.S. have an allergy to cow's milk. For them, drinking it could lead to life-threatening anaphylaxis or unpleasant symptoms like skin rashes, stomach pain, or diarrhea. Other children might also suffer from lactose intolerance, which is less severe than an allergy, but can still lead to uncomfortable symptoms like cramps, bloating, nausea, and gas. Lactose is a sugar found in cow's milk, but it is not present in dairy-free alternatives like soy milk.

In fact, for any child who can't (or simply doesn't want to) drink cow's milk, soy milk is a safe, nutritious alternative. As mentioned above, soy milk is a good source of calcium, as well as other nutrients like protein, omega-3, potassium, vitamin A, choline, folate, and vitamin B.

Soy should be offered to children slowly at first, so they have a chance to get used to the taste. Going slow also allows time to look for signs of soy milk allergies. Like cow's milk, soy milk allergies can produce symptoms like rashes and diarrhea. However, it's important to note that soy milk allergies are not as common as cow's milk allergies. Research suggests that only around 0.4% of American children have soy milk allergies. That said, they are more common in babies and young children than teens and adults.

The soy milk market is huge, and it's growing. In 2023, it was valued at more than $10 billion, and by 2032, it's expected to exceed $16 billion. This means that most grocery stores offer at least one variety of soy milk on the shelves. But you don't have to buy soy milk at all, because it is possible to make it from home in your own kitchen.

To make your own soy milk, all you need are dried soybeans and water. You'll need to soak the beans first, for up to 17 hours or as little as eight hours, depending on the temperature. After that, you'll need to drain the beans and then heat them with water, before blending them together to create a thick, creamy liquid. There are a number of recipes online, each of which varying slightly in method, but, in general, making your own soy milk is a relatively uncomplicated process.

There is one important thing to keep in mind though if you're going to make your own soy milk from scratch. While your DIY blend will be a good source of protein due to the soybeans, it will not be fortified with nutrients like calcium like many of the soy milk products you can buy from grocery stores.

Most soybeans in the U.S. are genetically modified, which means that much of the soy milk in the U.S. is made with genetically modified organisms (more commonly known as GMOs). GMO soybeans have been genetically engineered to be more resilient to external threats, including pests and herbicides. The beans still taste and look the same, but they are just stronger, and less likely to be affected by the chemicals used on croplands.

Some people choose to avoid GMO food and drink, like soy milk, because they are concerned about potentially negatively impacting their health and increasing the risk of diseases, like cancer. However, right now, there is no credible research to suggest that GMO foods are dangerous to consume. The U.S. Food and Drug Administration has also confirmed that GMO foods are safe for humans and will not cause any more harm than non-GMO foods.

However, for those who prefer to consume non-GMO foods, there are non-GMO soy milk options on the market. U.K. brand Alpro, for example, does not use GMO soybeans in its soy milk products. Silk's soy milk products are also certified by The Non-GMO Project, which is an organization dedicated to verifying non-GMO products across North America.

Prostate cancer, which impacts the prostate gland, is common in the U.S., affecting millions of people across the country. It can be serious, but most manage to live with the disease for many years. 

Just like with breast cancer, some people are concerned that consuming soy milk could raise the risk of prostate cancer. Again, these concerns are to do with its isoflavone content. However, as with breast cancer, there is little research to support the theory that soy milk may make prostate cancer more likely to develop. In fact, there is research to suggest the opposite. Again, because these compounds help to reduce inflammation and oxidative stress in the body, isoflavones may help to reduce the risk of prostate cancer, not increase it.

Furthermore, soy products have been linked with a reduced risk of cancer in general. In 2024, one meta-analysis reviewed several studies concerning soy consumption and cancer, which involved more than 900,000 participants in total. The researchers found that those with a higher intake of soy products had a 31% lower risk of cancer. When looking at soy milk, specifically, they found that higher intakes of soy milk were associated with a 25% reduced risk of cancer. The drop was particularly significant for gastrointestinal, ovarian, and upper aerodigestive cancers.

Dementia — which is a general term for a group of diseases that cause deterioration in the brain — is a growing problem around the world. Right now, there are more than 55 million people who are living with dementia diseases around the world. The most common is Alzheimer's disease, but some also suffer with other types, like frontotemporal dementia or vascular dementia.

There are many factors that increase the risk of dementia. Simply aging, for example, is a key driver of these diseases, which are more common in adults over 65. However, alcohol consumption, smoking, depression, and diabetes may also make dementia more likely to develop. Despite some myths around it, however, soy milk is unlikely to increase the risk of dementia. In fact, there is no evidence to substantiate any concerns that soy milk consumption could lead to dementia. There is, however, research to suggest that consuming soy products like soy milk could reduce the risk. Once again, this could be because of those anti-inflammatory, antioxidant isoflavones.

One study, published in The British Medical Journal in January 2025, suggested that while dietary choices can impact dementia risk, it is not soy milk people should be worried about. The research linked high consumption of processed meats and ultra-processed foods with a potentially higher risk of the diseases. The same study highlighted that soy milk was associated with a decreased risk of developing dementia.