Taking this popular supplement may cause harm, especially as you get older

I write a good bit about the importance of the gastrointestinal (GI) microbiome, the environment in your gut where billions of healthy probiotic bacteria thrive. It has a big role in regulating your overall health—from digestive health all the way to cardiovascular, cognitive, immune system, mental, and metabolic health.  

That’s why it may come as a bit of a surprise that I always advise against taking a daily probiotic supplement. Especially since so many mainstream doctors and natural “know-it-alls” recommend them! 

So, let’s revisit why I’m against taking them. And then, I’ll share some new research that further explains why taking a probiotic supplement is an entirely fruitless endeavor…and may even cause great harm, especially as you get older. 

Confusion abounds regarding probiotic supplements 

The mainstream really gets it wrong when it comes to probiotic supplements (as they do with pretty much all supplements). For example, mainstream doctors will recommend taking them to help offset digestive upset following a course of antibiotics. And some natural know-it-alls, who really ought to know better, just add to the confusion. 

So, let’s take a moment to clear up a few things …  

Probiotics are the “good” bacteria that live in your GI microbiome. They are critical to your overall health and longevity. 

However, it’s important to know that hundreds of thousandsof different species of probiotic bacteria live in your microbiome. And—throughout your life, many factors influence the evolving makeup of your microbiome—including birth conditions, diet, sanitation of living environment, diet, physical problems, and drug intake.  

Therefore, by artificially supplementing one or two specific strains (such as acidophilus) into the mix of hundreds of thousands of strains of probiotics naturally in your gut, you’re highly unlikely to accomplish much at all…much less alter the course of a disease. Worse yet, research shows taking a probiotic supplement can actually cause great harm by upsetting the natural, delicate balance of bacteria in your gut. 

Plus, new research now shows that your microbiome grows even more unique as you age, making a standard, “one-size-fits-all” probiotic supplement even more inappropriate… 

A more unique microbiome as you age is a sign of good health 

For this new study, researchers analyzed features of clinical information, genetics, and GI probiotic composition in more than 9,000 people between the ages of 18 and 101 years. They paid particular attention to a group of more than 900 older adults, between the ages of 78 to 98 years, to determine the role of the microbiome in healthy aging. 

They found that healthier people have an increasingly unique “signature” microbiome composition as they get older. Specifically, beginning in mid-to-late adulthood, they have fewer “core” probiotics. (“Core” probiotics, like bacteroides, are common bacteria typically found in most younger people.)  

Secondly, they have more unique bacteria, such as a probiotic metabolite called phenylacetylglutamine. This metabolite showed the strongest association with uniqueness and is found to be high among centenarians (people older than 100 years).   

Lastly, the more unique an older person’s probiotic profile, the more likely they were to live to an advanced age.  

By comparison, less healthy people did not undergo this kind of specialization in their microbiome as they got older. And they retained a higher number of “core” probiotics. 

But when it comes to your GI microbiome as you get older, it’s healthy when “shift happens.” That’s just another reason why the “one-size-fits-all” probiotic supplements don’t work…and may cause great harm. 

Your microbiome is individual—just like you

This important research further busts the concept that taking a “standard” probiotic supplement can help your gut—because there’s no such thing as a “standard” microbiome. And, on the contrary, developing a unique microbiome as you get older is key.  

Therefore, to help build your microbiome’s unique diversity as you age, I recommend doing the following: 

  1. Eat a balanced diet of whole foods to nourish your entire body, including your microbiome. 
  2. Cut out processed foods, refined carbs, and sugars—all of which poison probiotics. 
  3. Eat prebiotic foods that feed your natural probiotics—including fermented and pickled vegetables like sauerkraut, as well as apples, asparagus, avocados, bananas, garlic, leeks, onions, whole grains (like barley and oats), and yogurt. 
  4. Consider taking botanical supplements, like curcumin and ginger, or incorporate the spices liberally into your homecooked meals, as they help support metabolism in the GI tract, before sugar is absorbed into the blood. 
  5. Skip the antibiotics, unless they’re absolutely necessary to help clear a serious, life-threatening infection. 
  6. Say “no” to probiotic supplement pills. They just don’t make sense, don’t work, and can be dangerous to your health. 

You can learn much more about the dangers of probiotic supplements in the December 2018 issue of my monthly newsletter, Insiders’ Cures (“WARNING: New research shows probiotic supplements may be doing more harm than good”). Not a subscriber? No problem! Click here to become one today. 


Gut microbiome pattern reflects healthy ageing and predicts survival in humans.” Nat Metab, 2021 Feb;3(2):274-286. doi.org/10.1038/s42255-021-00348-0. Epub 2021 Feb 18.