Over the last few years, you may have noticed that the dairy section at your local grocery store has grown to feature far more than your run-of-the-mill milk selection. Nowadays, there are tons of brands to choose from, and yes, most of them are plant-based.

The move to plant-based milk has been a long time coming, considering an estimated 68 percent of people worldwide are lactose intolerant (30 to 50 million adults in the U.S. alone) and research shows that nearly 1.3 percent of the total carbon emissions produced in the United States—which is one of the main drivers of climate change and a harmful greenhouse gas for our environment—is due to the dairy industry. Comparatively, plant-based milk emits far fewer emissions and requires far less land use than the dairy industry.

Aside from the positive outcomes for the environment, plant-based milk options have been shown to offer tons of health benefits, too. But with so many options to pick from—oat, soy, almond, rice, and the list goes on—which one is the best one, at least in terms of digestion? We recently caught up with Will Bulsie wicz, MD, a gastroenterologist and New York Times bestselling author of The Fiber Fueled Cookbook, who spilled the beans milk on the number-one type of plant-based milk for gut health—his answer may surprise you.

The best type of plant-based milk for gut health, according to a gastroenterologist 

In a recent Instagram video, Dr. Bulsiewicz revealed that soy milk is hands-down his drink of choice (in the dairy section, at least) for several reasons. For starters, he says that soy milk is a plant-based milk that offers just as much protein and essential amino acids as cow’s milk. But although soy milk is on par with cow’s milk in terms of protein and essential amino acids, it outperforms dairy milk in many other ways.

Soy also contains an important anti-inflammatory agent often linked with longevity-boosting properties. “Soy milk contains isoflavones, which are plant compounds linked to various health benefits, such as reducing the risk of heart disease and stroke, lowering blood pressure, and improving bone health,” Dr. Bulsiewicz says. Additionally, according to the gastroenterologist, consuming soy milk can potentially reduce the risk of prostate cancer. “While there are concerns that dairy milk increases the risk of prostate cancer, soy milk may reduce prostate cancer risks,” he says.

What’s more, Dr. Bulsiewicz notes that soy milk is naturally low in saturated fat, which can be beneficial for your cholesterol and heart health, too. And that’s not all—soy milk can potentially help with exercise recovery as well. “Combined with resistance exercise, soy milk has been shown to increase muscle mass comparably to dairy milk,” he says. (It’s worth noting, though, that these findings are from a study performed on seniors who were experiencing muscle mass loss.)

So, if your gut instinct is telling you to “buy the soy milk” by now, perhaps you should listen. In fact, it’s been shown to boost gut health by preventing inflammation and protecting against other diseases, too. “Research has suggested that soy milk induces changes in the gut microbiome that are beneficial, such as increasing Bifidobacteria levels,” Dr. Bulsiewicz says. BTW, bifidobacteria is a type of good bacteria that lives in your gut that plays an important role in digestion and breaking down complex carbohydrates.

That said, like most things in life, not all types of soy milk are created equally. And to that point, Dr. Bulsiewicz recommends always buying organic soy milk whenever possible. “From my perspective, it’s important for the soy milk to be organic because this ensures that the soy was not sprayed with glyphosate, the same chemical used in some types of weed killer. The evidence suggests that glyphosate affects more than half of the bacteria living inside us and can potentially harm them and induce dysbiosis, which is the term we use for a damaged microbiome,” he says.

What are some common misconceptions about drinking soy milk?

Although soy milk has been linked to many benefits, it’s also gotten a bad rap over the years. (To which Dr. Bulsiewicz calls B.S.) “Soy has been vilified in ways that I don’t understand,” he says. “There are claims that it causes breast cancer. Yet, soy intake is associated with a lower likelihood of having breast cancer, and in those with breast cancer, increased soy intake is associated with a lower likelihood of death or cancer recurrence,” he says. Additionally, Dr. Bulsiewicz dispels the idea that it can affect breast size due to the estrogen levels found in the milk. “There’s no evidence to support this,” he says.

How much soy milk should you drink a day?

In the muscle mass study cited above, research shows that drinking 200 milliliters (a little under a cup) of soy milk twice a day can help add muscle mass. However, Dr. Bulsiewicz notes that there are potential benefits to consuming even more. “For example, in the blood pressure study, they consumed 500 milliliters (about two cups) twice daily. The effect of soy milk on blood pressure was strong, dropping the systolic blood pressure by 18 points, which is as good as most blood pressure medicines,” he says. Although he notes that it’s unclear if the blood pressure benefits exist with smaller amounts of soy milk consumption.

Who shouldn’t drink soy milk

Because it’s non-dairy, soy milk is ideal for those with lactose intolerance. But those with soy allergies should avoid it altogether (for obvious reasons), and Dr. Bulsiewicz notes that those with a history of kidney stones should also consume it in moderation. According to Mayo Clinic, soy is believed to impact the absorption of common medications used to treat a low thyroid (aka hypothyroidism), so it’s important to space out the time between taking your meds and consuming soy, though they don’t recommend avoiding it altogether. “Plus, if you have low thyroid, it’s important to ensure you have adequate iodine intake,” he says. This is because consuming soy could increase your risk of developing hypothyroidism if your iodine intake levels are low.

On the whole though, soy is a beneficial food to add to your diet barring the above scenarios (or with certain best practices in place), so next time you find your self if the dairy/non-dairy section, consider picking up a quart.

An RD gives the full rundown on alternative milks: