All About Soy Milk: Nutrition, Benefits, Risks, and How It Compares With Other Milks

These days, there are more options when it comes to nondairy milk than ever before. The original plant-based alternative to cow’s milk, soy milk, is still in demand, but you may be wondering how it stacks up against other popular nondairy milk options, such as almond, oat, and coconut, and whether soy milk is safe for most people to drink.

Soy milk is a plant-based nondairy beverage that’s a popular alternative to cow’s milk. It’s made from soybeans, and many brands, such as Silk, fortify their soy milk with vitamins and minerals such as vitamins A, B12, and D, and calcium.

It can be a naturally good source of vitamin B6, magnesium, and folate.

“Soy milk offers culinary diversity, creamy texture, and a healthful nutritional profile, including essential omega-3 fatty acids [if fortified] and flavonoids that exert antioxidant, anti-inflammatory, and cardioprotective properties,” says Julieanna Hever, RDN, who specializes in plant-based diets in Los Angeles and is the author of The Vegiterranean Diet.

Besides soy milk’s excellent nutritional profile, there are many other reasons why you might want to try this beverage in your coffee, smoothie, or cereal. Maybe you dislike the taste of cow’s milk or are trying to avoid dairy and prefer soy milk’s taste or nutrient makeup to the other nondairy options.

There are many types of soy milk on the market, and the number of calories and amount of added sugar will vary by product. Always check the nutrition facts label on your brand of choice, as the nutritional content can vary widely. A 1 cup serving of unsweetened soy milk, fortified with calcium, vitamin D, and vitamin A, contains the following:

Calories: 93
Fat: 5 grams (g)
Carbohydrates: 3 g
Fiber: 0 g
Protein: 8.7 g
Calcium: 246 milligrams (mg)
Iron: 1.3 mg
Potassium: 386 mg
Sodium: 83 mg
Vitamin D (D2 + D3): 40 international units
Vitamin A: 142 micrograms

Here’s a glance at how soy milk compares with other milks, such as dairy milk and other plant-based milks.

Soy Milk vs. Dairy Milk

Of all the plant-based milks, soy milk (fortified with calcium and vitamins A and D) is the most nutritionally similar to low-fat cow’s milk.

“I call the soybean the incredible, edible bean. With all nine essential amino acids, soy milk is a good source of protein and is balanced in fats and carbs,” says Schmidt. It’s also naturally low in saturated fat.

Soy Milk vs. Other Plant-Based Milks

Soy milk bests almond milk in protein content, though almond milk may have fewer calories (just 46 per cup), but offers just 1.6 g protein.

There are some “added protein” versions of almond milk that use pea or soy protein to bump up the protein content, but you will need to check product labels to verify. Pea milk itself is a good source of protein, offering 8 g per 8 ounce serving.

Compared to oat milk, soy milk also offers higher protein content, though Oatly oat milk is higher in fiber (2 g) and carbohydrates (17 g).

Coconut milk and rice milk are other popular choices. Coconut milk is the least allergenic milk and contains more saturated fat (3.5 g) than other nondairy milks. Rice milk is often naturally sweeter. Neither option contains protein.

Here are some of the possible research-based benefits of adding soy milk to your grocery list.

May Lower the Risk of Breast Cancer

Eating foods with soy may lower the risk of breast cancer.

A meta-analysis also found soy isoflavones significantly reduce the risk of breast cancer recurrence.

The greatest impact was among postmenopausal breast cancer survivors eating 60 mg of soy a day.

May Lower the Risk of Heart Disease

Soy is rich in isoflavones, plant chemicals that belong to a group called phytoestrogens. Isoflavones in soy may also protect your heart by reducing LDL (“bad”) cholesterol and blood pressure. This remains controversial because studies conflict about whether soy and a lowered risk of heart disease have a direct relationship.

The majority of best-in-class studies to assess soy’s potential benefits for heart health have examined soy protein isolate (that is, just the soy protein), rather than soy-based foods (like soy milk or tofu).

May Protect Against Osteoporosis

Soy isoflavones may reduce the bone loss that contributes to osteoporosis after menopause by decreasing bone resorption, a process that breaks down bone tissue. Bone loss speeds up a few years before menopause, making the maintenance of bone density especially important for menopausal women.

May Be Anti-Inflammatory

A review of seven studies found that drinking soy milk significantly reduced two proteins that cause inflammation, called C-reactive protein and tumor necrosis factor. Researchers think that soy inhibits one of the body’s major pathways to creating inflammatory proteins.

One isoflavone found in soy, genistein, has been found to have anti-inflammatory properties.
However, more research on larger sample sizes needs to be done to confirm soy milk’s anti-inflammatory properties.

Over the years, soy has gotten a bad reputation among people who believe that soy increases cancer risk, especially breast cancer risk. This is a common misconception based on animal studies that found that when rodents consumed high doses of isoflavones, they were more likely to develop breast cancer. But because rodents and humans process soy differently, these animal studies may not be reliable.
In addition, the amount of soy fed to the rodents in these studies was much higher than what people would get from food.

In fact, for those looking to eat a diet that decreases the risk of cancer, whole soy foods are a smart addition. “[Whole] soy foods have been shown to decrease breast cancer recurrence and mortality in breast cancer survivors, and to reduce the risk of breast cancer and prostate cancers as well,” says Hever.

You can feel confident about drinking soy milk, says Hever, who follows guidelines for moderate soy consumption: one to two servings daily of whole soy foods, including soy milk, edamame, soy nuts, and tofu. Studies indicate that consuming up to three servings of soy foods per day is not associated with a higher risk of breast cancer.

If you are allergic to soy, avoid soy milk.

Another consideration is thyroid disease. One study suggested that soy products may interfere with thyroid hormone replacement medications used to treat hypothyroidism, though a meta-analysis of studies found that soy didn’t impact the thyroid’s natural hormone production.
Medical professionals suggest waiting at least one hour after taking thyroid medication before you eat in general — including foods or drinks with soy.
Talk to your doctor or endocrinologist to get personalized advice on adding soy to your diet.

There are a few considerations when choosing a soy milk. One is to look for a product that is unsweetened, says Hever. Sweetened versions can contain around 5 g of sugar or more per serving. For example, Silk’s original soy milk contains 5 g of added sugars, while their unsweetened version has none.

If you want a little flavor, opt for unsweetened vanilla.

Hever recommends choosing organic, if it’s in your budget.

Finally, read the label to make sure your soy milk is fortified with extra vitamins and minerals, including calcium and vitamin D. Soy milk doesn’t naturally contain calcium.