Are Probiotics Bad for You?

May 03, 2019 5 min read

Potentially, probiotics are likely one of the most misunderstood dietary supplements out there at the moment. Chances are that you’ve heard of the benefits of taking them. Most people have at least a passing understanding of how taking probiotics can improve the immune system, help with weight management, or even that gut bacteria could help prevent cancer.   

But what about the downsides? Arethere any potential risks in taking probiotics?

The short answer is, like most any food or supplement, there are potential downsides and yes, some people do experience adverse reactions especially if their gut is in poor health due to factors such as poor diet or the use of antibiotics. 

IMPORTANT: Anyone with a compromised immune system should take caution in adding any bacteria to their system. 

Can probiotics be bad for you? What does the science say?

As with all things concerning your health, it is always important to begin with the science behind it. The National Center for Complementary and Integrative Health points out that the “safety” issue regarding probiotics is largely determined by the state of your overall health. Generally speaking, any “adverse reactions” (and the risks are reasonably low at that) that healthy people might experience are no more serious than mild digestive upset, such as gas. However, people suffering from severe medical problems (like the critically ill) are the ones most at risk of experiencing more severe side effects.

And not all probiotic strains have been adequately tested for safety. For example, the Medical News Today published an article in December 2018 discussing an article written by Dr. Pieter A. Cohen from the Cambridge Health Alliance at the Harvard Medical School. The article underscored how strains of Saccharomyces boulardii used in foods and supplements have neither been proven to have any of its purported health benefits, nor adequately tested for safety.

Some people might rightfully find the lack of extensive testing to be disturbing. After all, before any pharmaceutical product hits the market, they undergo a rigorous testing and evaluation process. In fact, the U.S. Food and Drug Administration requires drug companies to submit ample evidence of safety and efficacy before allowing a new medication to hit the mass market. Which begs the question, should the same standards be applied to probiotics?

Well, perhaps, but you should also consider that any serious adverse reactions and risks to probiotics apply mainly to people whose systems are already immunocompromised. And so probiotics fall under the GRAS (Generally Recognized As Safe) standard.

So, while one could argue that probiotic supplements, and probiotics in general should definitely undergo safety tests to better ascertain potential risks, the reality is that unless you are suffering a seriously critical illness, your risk factor is relatively low. 

Probiotic Possible Risks and Adverse Reactions

According to a January 2019 article from Medical News Today, some of the more typical side effects from probiotic consumption include digestive symptoms (gassiness, bloating, diarrhea, etc.) and skin problems (rashes and itchiness). There have also been reported cases of allergic reactions, which are thought to be due to the fact that some probiotic supplements can produce histamine in your digestive tract.  

Another potential adverse reaction are headaches caused by the amines in certain probiotics. Biogenic amines are substances that form when protein-containing food age or ferment. For those that are sensitive to amines, these substances can increase or decrease blood flow to your brain, and so possibly trigger headaches.

And, in some rare instances, the bacteria and yeasts in probiotics can enter the bloodstream causing infections. There have even been cases of where fungi and bacteria have been later found in the blood. However, once again, these instances are found with people that already have compromised immune systems. 

Have some probiotic strains been proven “safe”?

Fortunately, if you are in reasonably good health then the benefits far outweigh any mild side effects that you might experience. And, to keep things simple, you are likely to get the most “benefits” by sticking with probiotic strains in the Lactobacillus and Bifidobacterium family–readily found in most types of yogurt. According to an August 2018 article published by UAS Labs, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Lactobacillus plantarum have been proven to aid in healthy digestion, as well as boost your immune system.

Bifidobacterium strains such as Bifidobacterium lactis, Bifidobacterium bifidum, and Bifidobacterium longumnot only support digestion, but can also help relieve constipation, intestinal discomfort, and can even help to relieve stress in the case of Bifidobacterium longum.

Probiotic strains such as Lactobacillus acidophilus, Bifidobacterium longum and Lactobacillus reuteri can improve cardiovascular health by lowering LDL cholesterol while encouraging increases in HDL and a lowering in triglycerides. 

Studies have shown that probiotic strains (such as Bifidobacterium longum, Bifidobacterium breve, Lactobacillus helveticus and Lactobacillus rhamnosus) digest and ferment fiber into short-chain fatty acids that nourish the gut, and nourish your brain and central nervous system. Other research, into these probiotic strains in particular, have shown lowering of stress and anxiety levels.

Continued research into a) the overall safety of probiotics, b) the “best” strains and c) their proper use is in order so as to allay any concerns as well as to establish the benefits and to more accurately identify potential side effects. In the meantime, sticking with probiotic strains with a “proven track record” will certainly help your chances of avoiding any possible adverse reactions. 

Should You Make Dietary Changes or Take Probiotic Supplements?

Much of the work done to examine the potential risks of introducing probiotics into your system have looked at individual strains or probiotic supplements.

The truth is that the gut microbiome is very complex and its mix of bacteria quite varied. And so, much of the recent advances in improving your gut “microbiome” have focused more on improving your gut health–and from there, better health overall–by feeding your gut bacteria the foods that they like and avoiding the foods, drugs, medicines and such that inhibit their growth.

This approach encourages your gut's microbiome mix to grow in a more natural manner–it is kind of like fertilizing a garden.

Arguably, the safest and most EFFECTIVE route is to cut back–or eliminate entirely–foods such as simple carbohydrates, processed foods, additives, sugars and such (you know the offenders!). And then to add foods that your gut bacteria love, such as: resistant starches (green bananas, sweet potatoes, yams, yucca, taro root and others), lots of dark green cruciferous plants (broccoli, kale and such) and fermented foods (back to yogurt and sauerkraut again!).

And, unfortunately, many drugs, medicines and OTC painkillers (such as ASIDs) can wreak havoc on your gut. Use them only as truly needed and your gut will thank you! 


At the end of the day, is there a downside to taking probiotics? Yes, but the adverse reactions for most of us are about the same as those you’d expect from consuming particular fruits, vegetables, or dairy products that you may be sensitive to.

The answer to a healthy gut, and better health, is more than simply adding a probiotic supplement or capsule. One should also address the dietary, lifestyle and environmental factors that led to an unhealthy gut in the first place. Otherwise, just taking a supplement may not only be ineffective but could raise your chances of experiencing adverse gut reactions.

For most of us, the benefits of taking probiotics far, far outweigh any potential downside.

If in doubt, then check with your doctor first–particularly if you have a compromised immune system, in which case it is highly recommended that you seek the advice of a qualified medical professional before introducing any probiotics supplements to their body.


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