Is Soy Milk Good for You? Milk ain't what it used to be

A decade ago, if you went to a supermarket and looked for milk, you would have found, well, milk. Nowadays, there’s soy milk, oat milk, almond milk, coconut milk, you name it.

But are these alternatives actually healthy for you? Out of all of them (including dairy), soy milk is probably the healthiest. Here’s why.

soy milk and cookies — Image credits: Mirza Mustofa.

Soy milk, a popular plant-based alternative to cow’s milk, has gained a loyal following over the years. Touted for its numerous health benefits, soy milk is made from whole soybeans or soy protein isolate.

Soy is a complete protein, so it offers a high-quality protein source for those looking to avoid dairy. According to recent research, it’s more nutritious than dairy milk in some ways. It has an excellent nutritional profile and carries several health benefits. Let’s dig in.

Is Soy Good for You?

Soy is a legume that has been a staple in Asian diets for centuries. It’s packed with nutrients, including high-quality protein, fiber, vitamins, and minerals. Soy milk isn’t the most soy-rich product (of course, it’s mostly water), but it still carries soy’s health benefits to some degree.

Of course, you can’t “milk” soy. The name “soy milk” is more of a reference to the type of drink, it’s not milk per se — obviously. In fact, the dairy industry has been pushing against plant-based alternatives, asking legislators to ban them from calling themselves milk. This has been successful in the EU where such products are known as “soy drinks”, but not in the US.

Regardless of what you call it, there are several methods for making soy milk. The most common involves soaking, grinding, and boiling soybeans. The resulting liquid is then strained to remove solid particles, leaving behind a smooth, creamy beverage. Commercially produced soy milk often has added vitamins and minerals, such as calcium and vitamin D, to mimic the nutritional profile of cow’s milk.

Before we look at soy milk specifically, let’s look at some of the benefits of soy in general.

Heart Health

Research has consistently shown that soy can help lower LDL (“bad”) cholesterol levels, which is a key risk factor for heart disease.

“Many soy products should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fiber, vitamins, and minerals and low content of saturated fat,” concluded an American Heart Association science advisory.

Another study conducted in 2021 on around half a million people from China found that people who ate soy products have lower odds of dying from a heart attack compared with people who never or rarely ate soy.

“At no time since the original claim for soy as a reducer of serum cholesterol has its ability been in question,” says David Jenkins, professor of nutritional sciences and of medicine at University of Toronto. “It’s been consistent since 1999. The data have not changed.”

“A cumulative meta‐analysis of the data selected by the FDA indicates continued significance of total cholesterol and low‐density lipoprotein cholesterol reduction after soy consumption,” reads another study.

The FDA has even approved the regular consumption of soy protein as part of a diet low in saturated fat and cholesterol, noting that this may reduce the risk of heart disease.

Bone Health

Soy contains a group of compounds called isoflavones, which have been linked to improved bone health. Although the link between soy and bone health is still being investigated, studies have generally found positive results.

“Although the optimal amounts and types of soy foods needed to support bone health are not yet clear, dietary pattern evidence suggests that regular consumption of soy foods is likely to be useful for optimal bone health as an integral part of a dietary pattern that is built largely from whole plant foods,” one study concluded.

Isoflavones may help increase bone mineral density and reduce the risk of fractures, especially in postmenopausal women.

Cancer Prevention

Soy has been studied for its potential role in cancer prevention, with mixed results. Some studies have suggested that soy isoflavones may have protective effects against certain types of cancer, such as breast and prostate cancer.

“The consumption of soy isoflavones can reduce the risk of breast cancer in pre-menopausal and post-menopausal women,” one recent study read. A meta-analysis of multiple studies concluded that:

“No studies reported soy intake increased tumor development. The epidemiological data are also inconsistent, although consumption of nonfermented soy products, such as soymilk and tofu, tended to be either protective or not associated with cancer risk. [..] Protective effects were observed for both hormone‐ and nonhormone‐related cancers. While a definitive statement that soy reduces cancer risk cannot be made at this time, there is sufficient evidence of a protective effect to warrant continued investigation.”

Indeed, more research is needed to confirm these findings and determine the optimal amount of soy intake for cancer prevention. But the evidence seems to suggest a protective effect, though that effect is insufficiently quantified.

Menopause Symptoms

Soy isoflavones have been shown to help alleviate some symptoms of menopause, such as hot flashes and night sweats. They may also help improve sleep quality and reduce depressive symptoms in menopausal women.

How soy milk compares to dairy and other plant-based alternatives

There are already numerous types of soy milk products on the market. They can have wildly different nutritional profiles. Here, we’re mostly referring to “plain” soy milk. This means products without any sugar and additives that are unhealthy. Some soy milk products are heavily processed, and that can make them less healthy.

So here, we’ll be focusing on unprocessed or minimally processed soy milk, which is what I’d recommend in terms of health. However, many soy milk brands are fortified with calcium and vitamin D to support bone health — that’s not a concern.

soy milk alternative milk comparison scheme — Cow’s milk is compared with various plant-based milk. Image credits: McGill University.

“Plant-based milk alternative products have been increasing in popularity, so it is important for consumers to understand how consumption of these products can affect their overall intake of essential mineral micronutrients,” Dr. Benjamin Redan, Research Chemist at the FDA, told ZME Science last year. Redan was part of a team that measured the mineral content in various type of plant-based milks.

“The minerals we measured in these products are known to play a role in many functions in the body, including normal immune system function, proper regulation of blood pressure/glucose, and bone health.”

Rsearchers looked at a total of 85 samples from almond, cashew, coconut, hemp, oat, pea, rice or soy milk. They found significant differences between different product types, as well as within brands of the same type of product.

The team found that pea-based drinks have, on average, the highest content of phosphorus, zinc, and selenium, while soy had the highest amount of magnesium. However, both pea and soy milk had higher levels than cow’s milk.

“Pea-based milk alternative products contained, on average, higher amounts of a majority of the measured mineral micronutrients versus soy-based milk alternatives. Either soy- or pea-based milk alternatives contained higher amounts of the target mineral micronutrients in comparison to the other six types of plant-based milk alternatives we assessed (almond, cashew, coconut, hemp, oat, and rice-based beverages),” Redan added.

“These results indicate that certain plant-based milk alternatives can be a source of mineral micronutrients, but differences across product types should be taken into account when considering their nutritional value.”

However, perhaps the most comprehensive study that compared plant-based milk alternatives and dairy milk was published in 2018. That study concluded that by far, soy milk is the best alternative and the only major downside is its taste, which is unpalatable to some.

“It is quite clear that nutritionally soy milk is the best alternative for replacing cow’s milk in human diet. But, various issues including the ‘beany flavor’ and presence of anti-nutrients are major hurdles which encouraged people to look for more alternatives like almond milk, etc.

“Though, almond milk also has a balanced nutrient profile and much better flavor, the nutrient density and the total number of calories are not as rich as that of cow’s milk. Hence, when consuming almond milk care should be taken that various essential nutrients are available through other sources in the diet in appropriate quantities.”

“Rice milk and coconut milk cannot act as an ideal alternative for cow’s milk because of limited nutrient diversity, but they are the options for consumers that are allergic to soybeans and/or almonds. Further research is needed to understand the effect of various conventional and novel processing methods on the nutrient profile, flavor and texture of these alternative milks.”

Soy milk vs dairy milk

Ultimately, soy is probably the healthiest plant-based milk alternative you can get. But even compared to dairy milk, it fares very well. While cow milk does have its own advantages, here are some ways in which soy fares better.

Lactose-Free

Soy milk is naturally lactose-free, making it an ideal choice for those who are lactose intolerant or have difficulty digesting lactose, a sugar found in cow’s milk. This can help prevent uncomfortable symptoms such as bloating, gas, and diarrhea.

Dairy Allergy Alternative

For those with a cow’s milk allergy, soy milk can be a safe and nutritious alternative. It provides a similar taste and texture to cow’s milk, making it an easy substitution in recipes and beverages.

Granted, some individuals may have a soy allergy. If you have a known soy allergy, it’s essential to avoid soy milk and other soy-based products.

Plant-Based Complete Protein

As a plant-based protein source, soy milk is an excellent option for vegetarians, vegans, and those looking to reduce their consumption of animal products. With a complete amino acid profile, soy milk provides the essential building blocks for muscle growth and repair.