What You Should Know Before Taking Probiotics


It’s one of those buzzy health trends: probiotics.

You may have heard about them from your well-meaning aunt after she read about this “helpful” new health trend online. “What if you tried probiotics for your digestive issues? Or maybe it would help with your depression,” she helpfully suggests. Before you know it, the word “probiotic” is popping up everywhere — on news reports, on display at the drugstore when you pick up your regular meds and then in conversation with your best friend. But what are probiotics? What are they do? Are they safe? Do they work? Should you be taking them? 

We took a deep dive into the wonderful world of probiotics — and your gut bacteria, yay! — to help you answer that question. From the latest research to expert opinions and a closer look at the microorganisms in charge of your system, here’s everything you need to know.

What Are Probiotics?

Probiotics are “good” bacteria found in your gut microbiota or gut flora that help maintain your digestive and immune systems. Research suggests that taking probiotics — typically from two groups of bacteria called Lactobacillus and Bifidobacterium, or yeasts like Saccharomyces Boulardii — can help crowd out “bad” pathogenic bacteria.

As trendy as they are right now, probiotics have a long history. Back in 1907, Russian microbiologist Elie Metchnikoff discovered that drinking fermented milk, a natural source of probiotics, had health benefits, especially in the large intestine. There’s also evidence that fermented milk products — aka probiotics — were used in Roman times to treat a variety of maladies.

Like many popular health fads, probiotics are big business. A 2012 National Health Interview Survey found that nearly 4 million U.S. adults used probiotics or prebiotics — four times the number of people who used them in 2007. Probiotics rank as the third most-used natural product in the country, making an estimated $40 billion in profit in 2017.

Despite their popularity, how probiotics work remains a bit of a mystery.

A Closer Look at Your GI Tract

Part of the difficulty of understanding probiotics is the sheer complexity of our gastrointestinal (GI) tract. The GI tract includes our mouth, stomach, small intestine and the large intestine or colon. From start to finish — mouth to *ahem* number two — it takes food an average of 55 to 72 hours to travel through your digestive system.

Along the way live an estimated 100,000 billion bacteria comprised of more than 500 different species. Together they make up the gut microbiota, which functions much like an organ. In fact, the GI tract is the largest immune organ in the body. It’s in charge of defending against bad bacteria and supporting good nutrition.

If probiotics live in our gut, then why do people expect health benefits as far ranging as digestive health to mental health? It turns out bacteria gossip with each other. Roger Clemens, DrPH, co-founder and executive vice president of scientific operations for PolyScience Consulting and adjunct professor of Pharmacology and Pharmaceutical Sciences at the University of Southern California in Los Angeles, said bacteria in the GI tract can signal other bacteria in far-reaching parts of the body. He told The Mighty:

We’ve certainly seen that some of these bacteria, they will signal or talk to cells, and those cells will talk all the way up and down the immune system. If we can talk to the immune system in the gut, sometimes that will affect what happens say in the ear, and we’ve certainly seen that certain kinds of bacteria actually reduce the risk of a condition.

Testing Probiotic Health Claims

In the midst of this sea of talking bacteria, there are many probiotic health claims. Which of these claims really hold up?

Here’s the short version: Probiotics could potentially have a positive impact on lowering cholesterol, treating urinary tract infections, lowering blood pressure, reducing skin conditions like eczema, treating gastric ulcers, treating vaginal yeast infections, preventing colon cancer, reducing anxiety and depression and weight loss. But don’t get too excited. None of these benefits have been proven conclusively. There are often contradictory results or negative outcomes. More testing is needed.

Probiotics do have one clear benefit. Multiple studies have shown that probiotics can reduce diarrhea. If you’re taking antibiotics and one of the side effects is diarrhea, probiotics may help. For antibiotic-related diarrhea, probiotics have been proven effective in both children and adults. Particularly promising for treating diarrhea is a strain of bacteria known as Lactobacillus Rhamnosus GG (LGG). One clinical review found “the administration of LGG reduced the risk of nosocomial diarrhea from 13.9 percent to 5.2 percent,” though the study is careful to point out this was the only strain that seemed effective.

Are Probiotics Safe?

Whether they help or not, probiotics are generally safe to try for healthy people. If you have other conditions, probiotics may not be safe. For those with serious infections, a weakened immune system, other illness or who have had surgery, evidence suggests probiotics are NOT safe. If you are interested in trying probiotics, be sure to talk to your doctor first as they can be dangerous for some.

Probiotics can cause side effects, including mild bloating, diarrhea or gas for the first few days of use. In some cases, they may lead to allergic reactions. They can also interfere with other medications you take, so check in with your doctor or a pharmacist if you take other meds. 

It’s also important to ask if probiotics are beneficial. Because of the number of different bacteria strains and the complexity of the GI tract, the amount of research it will take to pinpoint which strains most impact which health condition is a long-term project. Right now, the science isn’t there yet. 

Each person’s gut flora is unique based on a number of factors, including your age, culture, health and diet. In Japan, where they typically eat more seaweed, for example, people have a gut bacteria strain designed just for digesting seaweed. Whether or not probiotics will work for you, and which types might work for you, is really anyone’s guess.

“Like people, not all probiotics are the same and not everyone responds the same way,” Clemens said. “Ones that we see are safe, [the] question then becomes, ‘Are they really beneficial? Are they the right strain? Are they the right amount?’… There’s just a lot of different variables here when we’re looking at the applications of probiotics.”

Getting Probiotics From Food

There are two main ways to increase your probiotic intake. One is certain foods. Within 24 hours of changing your diet, studies have shown your gut microbiota will show identifiable changes.

Introduce a wide variety of cultured foods such as yogurt, kefir, kombucha and fermented vegetables like kimchi to your diet,” Cordialis Msora-Kasago, a registered dietitian and media spokesperson for the Academy of Nutrition and Dietetics, advised. “Choose food items whose label indicates that they contain, ‘Live active cultures’ as these most likely will provide you with the most probiotics at time of purchase.”

If you are interested in eating more probiotic foods, try adding sauerkraut, soft cheeses like gouda, pickles, tempeh, buttermilk, miso, natto, some juices and soy drinks to your shopping list.

The Difference Between PREbiotics and PRObiotics

You can also consider PREbiotics to boost the benefits of a healthy gut flora. Probiotics are the bacteria found in your gut while prebiotics are the food that good gut bacteria eat. Msora-Kasago told The Mighty:

Prebiotics are the non-digestible fibers that provide these bacteria with nourishment. Although the conversation tends to focus more on probiotics, prebiotics, found in plant foods like asparagus, beans, sweet potatoes whole wheat, garlic and onions, are equally as important. They provide nutrients for the probiotics, allowing them to grow and multiply.

However, simply eating more prebiotic foods may not matter. Each person’s gut microbiota is so unique and complex, there’s no one-size-fits-all solution to what your gut bacteria will want to eat.

“What industry typically fails to do is to provide the right prebiotics added to food that matches the bacterium that will use that food,” said Clemens. “In the foods industry and the supplement industry, they often hear the word ‘prebiotic,’ but basically with very few exceptions it’s something that’s off-the-shelf and has no impact whatsoever. They’re not paired. We don’t know what they do. They’re safe, yes, but do they really deliver? Sometimes yes and sometimes no.”

Looking at Probiotic Supplements

The other way to get more probiotics in your system is through supplements. Here’s where it gets a little tricky. Probiotics are regulated by the U.S. Food and Drug Administration as a food instead of a drug or medication. Accordingly, the FDA provides much less oversight for supplemental probiotics and manufacturers can claim whatever they want on their labels without proving their claims are true.

Several studies in the U.S. and Europe have found that probiotic supplements are often mislabeled. A 2015 study published in Pediatric Research found that only one out of 16 tested probiotic supplements matched the claims on the label. Another study found that the amount of bacteria in products is lower than what the label claims and the strains listed didn’t match.

What Probiotic Supplement Should You Take?

Discrepancies aside, the next natural question is, “Which probiotics should I take?”

“One of the biggest misconceptions about probiotics is that taking one strain will automatically yield great results for all ailments,” Msora-Kasago said. Considering nobody knows exactly what any single strain of bacteria does for you specifically, your best bet is to choose a supplement that includes many different strains.

You’ll also want to check expiration dates carefully as only live bacteria have a chance of working. Dead bacteria have absolutely no benefit whatsoever. And don’t be alarmed by the “billions” on labels. Most probiotic supplements will provide doses of at least 1 billion CFUs (colony forming units), and some provide much more, such as 50 billion CFUs. You’ll need to take them regularly to see potential results, according to Clemens:

Once you start the regimen [to] help modulate the gut…you must take it on a regular basis because these probiotic strains in general do not establish themselves. They don’t set up housekeeping [and] say, ‘I’m gonna live here in the gut and I’m gonna stay here and therefore I’ll do all my good stuff and you can stop taking me.’ The answer is no, because you have to take this on a regular basis.

Should You Be Taking Probiotics?

So now that we’ve looked at all the evidence, back to our original question: Should you be taking probiotics?

If you’re dealing with an illness, infection or take other medications, probably not. If you want to, be sure to check with your doctor first. If you’re healthy, it still doesn’t hurt to check with your doctor. The rest is really up to you.

Header Getty Image via Pitris.


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