WARNING: New research shows probiotic supplements may be doing more harm than good

There’s a lot of confusion about probiotics. And a lot more myth than science being spread by the natural products industry and practitioners who really ought to know better.

Probiotics are the “good” bacteria that live in your gastrointestinal tract (the microbiome). These micro-organisms are tiny but mighty—and essential to your overall health. Probiotics offer a wide array of benefits—from boosting your immunity, to improving your digestion, and even protecting against Alzheimer’s disease.

And mounds of research show that you can support and even increase your body’s natural supply of probiotics with certain foods (which I’ll talk more about in a moment).

But first, I want to clear up a major misconception. I’ve noticed that ever since probiotics became such a “hot topic” in today’s health market, this hype has led to lots of misinformation. Mainly, many people have been led to believe that probiotic supplements are just as—if not more so—effective than food.

In fact, in a survey conducted in 2017, 61 percent of the healthcare providers at the Stanford Medical Center recommended probiotic supplements to their patients.1

I’ve always questioned the basic biology and premise behind probiotic supplements. And so have other scientists. In fact, plenty of research shows that probiotic supplements simply aren’t effective.

And new research shows they may actually be dangerous for your health.

Rethinking probiotic supplements after antibiotics

This study, from Israel, found that the common practice of taking probiotic supplements during or after a course of antibiotics isn’t only ineffective, but may actually be unsafe.2

As I’ve mentioned before, antibiotics attack all bacteria in your body, including the “good” probiotic bacteria. So after you take antibiotics, your body has to restore its probiotic levels. The Israeli researchers decided to find out if taking probiotic supplements is the best way to do that.

They gave 21 volunteers a course of antibiotics and then split the people into three groups. One group took a probiotic supplement. Another group received a transplant of their own probiotic-rich feces that was collected before they took the antibiotics. And the final group did nothing, letting their GI microbiomes recover on their own.

The researchers found that for the fecal transplant group and the group that did nothing, microbiomes returned to normal within days. But the group that took probiotic supplements had to wait months for their microbiomes to be restored back to normal.

The researchers concluded that “contrary to the current dogma that probiotics are harmless and benefit everyone, these results reveal a new potential adverse effect of probiotic use with antibiotics that might even bring long-term consequences.”

Probiotic supplements are ineffective for the majority of people

The Israeli researchers also conducted a companion study in which they analyzed how effective probiotic supplements are at colonizing and boosting the microbiome.3

Other studies have tackled this topic, but they’ve only looked at probiotic content in stool samples—which doesn’t show if the probiotics are actually working in the upper GI tract.

In this study, researchers extracted samples from the digestive tracts of 19 study participants before and after they were given supplements containing the most common strains of probiotics.

The results illustrated what I’ve been talking about for years. Only eight of the study participants (42 percent) had any notable evidence that the probiotic supplements they took had colonized in their guts. And of those eight people, only three had what the researchers called “significant colonization.”

In other words, this study shows that most people’s normal digestive tracts prevent standard probiotic supplements from even taking hold.

The researchers believe this may be because some people’s immune systems actually fight the bacteria commonly found in probiotic supplements. That’s because everyone’s microbiome is different.

The right way to support your microbiome

The basic problem with probiotic supplements is that they’re designed to replace or restore probiotics in your GI tract. But as we’ve learned from these studies, they can’t even do that simple task.

The better, more effective option is to support the probiotics that naturally occur in your gut—with foods and organisms known as “prebiotics.”

Prebiotics fall into three categories. The first includes “active” foods that contain actual probiotic bacteria—including cheese (think cottage cheese, cheddar, parmesan, and soft, fermented types like Gouda); yogurt; and fermented vegetables like sauerkraut, tempeh, kimchi, and pickles.

Secondly, there are foods that contain fiber, which is nature’s prebiotic. These prebiotic foods include garlic, onions, asparagus, bananas, apples, flaxseed, barley, oats, and wheat bran.

The third includes certain herbs that are highly effective for microbiome health.

As I’ve written before, these potent herbal remedies go to work directly in the GI tract—influencing the GI-brain-body connections before being absorbed into the bloodstream. It’s a new scientific concept I call “biome-availability.”

The herb that can increase your probiotic diversity

One of the most effective of these “biome-available” herbs is turmeric, and its active ingredient curcumin. In fact, results from a new clinical trial show that curcumin actually has a prebiotic-like effect in the GI mirobiome.4

The researchers gathered 32 healthy adults and analyzed the DNA sequencing on their microbiomes. Results showed that the study participants had between 172 and 325 bacterial species in their guts.

The researchers then gave the participants either placebo tablets or tablets containing curcumin (from turmeric) and piperine (from black pepper). After eight weeks of this regimen, the researchers analyzed the participant’s microbiomes again.

They discovered that the curcumin/piperine group had a 7 percent increase in the diversity of bacteria in their GI tracts. But the placebo group had a 15 percent decrease in diversity. That’s a 22 percent difference. The researchers described curcumin’s effect on the GI microbiome as “prebiotic-like.”

Your microbiome is individual—just like you

What these studies teach us is that when it comes to your microbiome health, the whole concept of a “standard” probiotic supplement is non-existent—because there is no such thing as a “standard” microbiome. Instead, it’s much more effective to eat foods and take herbal dietary supplements that act as prebiotics, supporting your body’s own individual GI probiotics.

It all goes back to what I always recommend: A balanced diet with whole foods, partnered with dietary supplements, is almost always going to keep you healthier than popping a “one-size-fits-all” pill.

Your healthy microbiome checklist

The following foods and herbs can help support the probiotic bacteria already present in your GI tract.

  • Apples
  • Asparagus
  • Bananas
  • Black pepper
  • Barley
  • Cheese
  • Flaxseed
  • Garlic
  • Kimchi
  • Oats (whole grain)
  • Onions
  • Pickles
  • Sauerkraut
  • Tempeh
  • Turmeric
  • Wheat bran
  • Yogurt


1“Probiotic guidelines and physician practice: a cross-sectional survey and overview of the literature.” Benef Microbes. 2017 Aug 24;8(4):507-519. 

2“Post-Antibiotic Gut Mucosal Microbiome Reconstitution Is Impaired by Probiotics and Improved by Autologous FMT.” Cell. 2018 Sep 6;174(6):1406-1423.e16.

3“Personalized Gut Mucosal Colonization Resistance to Empiric Probiotics Is Associated with Unique Host and Microbiome Features.” Cell. 2018 Sep 6;174(6):1388-1405.e21. 

4“Effects of Turmeric and Curcumin Dietary Supplementation on Human Gut Microbiota: A Double-Blind, Randomized, Placebo-Controlled Pilot Study” J Evid Based Integr Med. 2018 Jan-Dec;23:2515690X18790725.