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Just a few years ago, probiotics seemed like a strange and foreign concept. Now research on the microbiome has exploded — science tells us having a diversity of microorganisms in the gut enhances immunity, digestion, and other aspects of health — and these beneficial bacteria have become a hot commodity. Probiotic supplements are currently a $1.7 billion U.S. industry, according to Euromonitor International, and New Hope Networks projects they’ll increase to $2.5 billion by 2018. Companies are taking the trend to the bank, too, adding probiotics to their cold-brew coffees, kale chips, granola, and even frozen burritos.

But a big question remains: Do these probiotic-infused foods and beverages actually make us any healthier? Can you really boost your immunity, knock out digestive woes, and generally feel better by munching on a snack that’s been bolstered with bacteria?

It’s complicated, says Dr. Amy Burkhart, an integrative-medicine physician in Napa, California. “Marketing and consumer demand for probiotics are definitely driving the uptick in these products,” she says. “That said, they may have some benefit — we just don’t know the specifics because the science isn’t there yet.” A lot depends on the type of product you buy and the exact strain of probiotic as well. Certain strains, such as Lactobacillus and Bifidobacterium, have more research behind them than others, and some fare better in food and beverage processing. “To be effective, probiotics must be either heat- and shelf-stable or refrigerated and maintained during processing and transport,” Burkhart explains. If they’re not, a good portion — if not all — of the probiotics in the product will be dead by the time you buy it.

There is one particular probiotic that’s been well studied, is heat-stable, and is popping up often in new products — a Bacillus coagulans strain called Ganeden BC30. Ingest a food or drink containing BC30, and chances are the probiotic will be alive and intact. However, many other probiotic strains being added to products do not demonstrate this stability, says Jeremy Burton, deputy director of the Canadian Centre for Human Microbiome and Probiotics.

On top of that, you also have to consider whether a probiotic-boosted food or drink is actually nutritious to begin with. “Will adding a small amount of probiotics to a snack bar or chocolate bar do much for you? I’m not so sure,” Burton says. “If the food itself is inherently unhealthy, it’s counterproductive to health.”

All of this begs the question of whether we need probiotics in the first place. Yes, they do help repopulate good gut bacteria. We’ve seen it happen in studies on people with digestive disorders or are taking gut-ravaging antibiotics. And nutrition experts now suspect that most of us have a less-than-healthy microbiome thanks to poor diets, so probiotics could certainly have the potential to help just about anyone. That’s what all of these food and beverage companies are hanging their hats on, anyway.

But that is also what’s dividing doctors. Some, like Burkhart, don’t see any real downside to probiotic supplements or foods, except for their high price tag. And since probiotics could aid immunity and digestion, they see no harm in seeking them out. Other doctors aren’t so convinced. “The strength of evidence is not sufficient for healthy individuals without any medical problems or digestive issues to be investing in daily probiotics,” says Dr. KT Park, a gastroenterologist at Stanford University School of Medicine. “I say spend the extra money per month on eating well instead of looking to probiotics for a quick, easy fix.”

According to Park, the average guy could greatly improve his gastrointestinal health simply by laying off processed foods and eating a wide variety of vegetables, fruits, grains, nuts, and seeds. “Plant fibers serve as fuel for our 100 trillion gut bacteria,” he says. “Strong evidence suggests a plant-based diet can optimize your gut microbiota profile by increasing the diversity and abundance of good bacteria.”

Along with loading up on plants, you can also support your microbiome with fermented foods, adds Park. That means plant-based items such as sauerkraut, as well as animal-based options like yogurt and kefir. Along with acting as probiotics, fermented foods supply prebiotics, which are basically food for existing bacteria to feed on. This combo gives fermented foods real potential to help keep your microbiota healthy — and probably more than some probiotic-laced burrito.

The bottom line is that probiotic-infused foods and drinks that are healthy to begin with probably won’t hurt much more than your wallet — and who knows, they could be giving your microbiome a boost. But if you can get more mileage out of apples, spinach, sprouted grains, and Greek yogurt, why not save your cash, and simply dial in your diet instead.