5 Things You Should Know About Soy Milk

updated Dec 17, 2019
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(Image credit: Rob Hainer)

If you’re lactose-intolerant, vegan, or just dairy-sensitive, the wild world of non-dairy milks out there can be overwhelming. Not too long ago, soy milk was the primary alternative to cow’s milk, but is it the best mylk out there?

Soy milk, like all milks, comes with some persuasive pros. It also has some drawbacks. This is the nuanced non-dairy world in which we live. Here’s what you should know.

1. It’s lactose-free.

On the bright side, soy milk is lactose-free — a non-negotiable if you’re lactose-intolerant.

2. It’s a good source of protein.

Soy milk is also the only existing alternative milk that can go head-to-head with cow’s milk on protein: Per U.S. News and World Reports’ breakdown, it has exactly the same amount as cow’s milk, at an estimated 8 grams. (the New York Times, looking at the label for Westsoy organic unsweetened plain soy milk, puts it at 9.)

3. It’s not a good source of calcium.

On the other hand, soy milk contains no calcium on its own. This may seem like a con, but there are two other factors to consider: 1) You can buy it fortified, which brings it up to the same level as cow’s milk, and 2) Our obsession with the bone-strengthening benefits of calcium may be somewhat overblown. In fact, it’s possible most of us are getting plenty of calcium — it’s just that we’re not absorbing it.

Why? Because we’re actually consuming too much protein. “High-protein foods such as meat, eggs, and dairy make excessive demands on the kidneys, which in turn leach calcium from the body,” the Guardian explains, suggesting that instead of increasing our calcium intake, we should be cutting back on protein.

By that logic, dairy products don’t help prevent osteoporosis, the Guardian says — they actually help cause it. That could help explain why some demographic groups who traditionally eat very little dairy and get all their calcium from vegetables — people in China, for example — actually have very low rates of osteoporosis. American women, meanwhile — some the the biggest consumers of calcium in the world — also have some of the highest rates of osteoporosis.

Bottom line: Your calcium-free soy milk? It might not be such a big deal after all.

4. It contains phytoestrogens.

So what about the buzzy idea that soy messes your hormones? Soy contains phytoestrogens, which are natural compounds that chemically resemble estrogen. That’s raised some concerns about dips in testosterone levels and lowered sperm counts in men, and trouble for women with estrogen-sensitive breast cancers. But according to an explainer in the New York Times, those fears aren’t all that founded — at least, not yet.

“A number of clinical studies in men have cast doubt on the notion that eating soy influences testosterone levels to any noticeable extent. And most large studies of soy intake and breast cancer rates in women have not found that it causes any harm,” says Dr. Anna H. Wu of the Keck School of Medicine at the University of Southern California. In fact, work by Dr. Wu and others has found that women who consume the equivalent of about one to two servings of soy daily have a reduced risk of receiving a diagnosis of breast cancer and of its recurrence.

5. It probably has added sugar.

Okay, so the lack of calcium and phytoestrogens may be no big deal, but one thing to definitely watch out for with soy milk? Added sugar. To mimic the natural, lactose-provided sweetness of milk, a lot of soy milks have added sugar. That’s not necessarily a deal-breaker, but depending on your diet and your taste, it does mean it could be worth investigating the unsweetened options.

Do you drink non-dairy milk? Do you prefer soy or another alternative?