Do Probiotic Supplements Actually Work?

Today I’m going to answer the trillion culture… oops I mean dollar question… Do you need a probiotic?

Well actually, the probiotic industry is more like a multi-billion dollar industry and , as we all know, when money gets in the way sometimes the science gets muddled.

But wait, what is a probiotic?!

You’ve probably heard by now that your gut is populated by trillions of  healthy bacteria.

As we continue to learn more about the positive health effects that these bacteria play in our bodies, it should come as no surprise that supplement companies have leveraged their increasing popularity by introducing a deluge of probiotic products to the market.

The Food and Agriculture Organization of the United Nations World Health Organization defines them as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.”

It’s honestly not really that much different than seeing a vitamin or nutrient supplement ( such as vitamin D) explode in popularity as a result of emerging research on health effects.

Now technically speaking, probiotics are not essential (they already exist in our bodies and their numbers can be facilitated through dietary means) nor are they necessarily elusive (several foods contain them + even more encourage their growth) but of course, a supplement generally allows you get MORE of something, with LESS effort.

With that in mind, I frequently get asked by otherwise healthy clients if they should take a probiotic.

The answer to that question is exactly what you will get out of today’s article, but you will have to keep reading.

What Do Probiotics Actually Do?

 So why have probiotics (both the actual bacteria in your gut and the supplemental form) become such a hot health topic in the first place?

 There are several reasons for this, but here are two of the big ones:

Number One – They prevent the infiltration and proliferation of “bad” bacteria in your gut through mechanisms such as supporting the GI tracts barriers, fighting for resources and potentially producing by products that prevent them from thriving.

Number Two- They play a role in supporting the human immune systems response mechanism.

Obviously, these are things you want to have working in your favour.

Can I Maintain My Healthy Gut Bacteria Without Probiotic Supplements?

You sure can, in most cases ( more on this later in the article).

But hey guess what, as with almost all things related human health, it all starts with your diet.

Consuming a diverse fibre-rich diet is probably the single most influential thing you can do to positively influence the bacteria in your digestive tract because it generally requires the assistance of these bacteria to break down.

For example, the bacteria living in your colon release enzymes largely responsible for the fermentation of fibre in your gut, which leads to the production of what are known as SCFAs (short chain fatty acids).

According to this 2016 review by Rios-Covian et al SCFA’s have distinct physiological effects: they contribute to shaping the gut environment, influence the physiology of the colon, they can be used as energy sources by host cells and the intestinal microbiota and they also participate in different host-signaling mechanisms.

In other words, the presence of these fatty acids alters the environment of your gut, making it harder for harmful bacteria to thrive.

Certain types of fibre, often referred to as prebiotic fibre, are particularly adept at acting as “food” for your healthy bacteria and facilitating the production of these SCFAs.

Prebiotic fibres can generally be found in healthy high fibre foods including whole grains, pulses, fruits and vegetables but are found in the highest concentration in specific foods such as:








An emerging body of evidence also suggests that a group of antioxidant compounds, known as polyphenols, may also have some prebiotic capacity.

There’s a catch though!  Some people living with IBS may recognize prebiotic foods as symptom inducing.

Large amounts of these foods, especially when introduced rapidly, may also lead to gas and bloating in otherwise healthy individuals.

If you find yourself in this category, my article on low FODMAP soluble fibre rich foods may help.

You can also support your gut microbiome via the consumption of foods that contain varying levels of probiotics such as kefir, yogurt, kimchi and kombucha.

These foods are not necessarily essential for good health, but they are certainly an option.

So When Is Diet Not Enough?

If you are otherwise healthy with a strong dietary pattern, I’m not sure there is really a compelling reason for you to pursue probiotic supplementation.

However, if something has happened that compromised either the healthy bacteria in your body ( such as an antibiotic) OR their environment (infections, ailments of the digestive system like IBS) that may be a different different story.

In these cases, supplementation with a probiotic may help.

Let’s take a closer look at the evidence.

Evidence Summary

Adapted from an extensive 2018 meta-analysis of probiotic efficacy by Hungin et al,  I am offering a chart below that compares the level of evidence available to support the effect of probiotics in common contexts.

The higher level of evidence, the stronger the body of evidence exist of the effect.


Overall symptoms and abdominal pain in IBS

Prevention or reduction of diarrhea in those on antibiotics

Prevention or reduction of diarrhea in patients being treated for  Helicobacter pylori



Bowel movements and bloating/distension in IBS   ( Want to learn more about bowel movements? Read my article on poop)



Overall symptoms in IBS-D, Flatus in IBS-D, Constipation


Very Low:

Overall symptoms in IBS-C, Diarrhea in IBS


Other Potential Uses

Ulcerative Colitis

I encountered two recent meta-analysis (1, 2) which specifically identified the VSL#3 probiotic blend as potentially effective treatment modality in ulcerative colitis remission.

Lactose Intolerance

According to a recent 2018 systematic review by Oak et al, there is an overall positive relationship between probiotic use and lactose intolerance.

Based on the review, it appears that the Bidifobacterium animalis probiotic had the best evidence supporting its use in relieving the symptoms of lactose intolerance.

Acid Reflux

Although not considered a traditional first line defense, there is limited evidence to suggest a potential supporting role for probiotic supplementation in the mitigation of GERD symptoms such as heart burn and regurgitation.


Not All Probiotics Are Made Equal

As the above examples demonstrate, it’s important to recognize that not all probiotics are alike.

If a certain type of Lactobacillus probiotic has been proven to be effective in treating a condition, it does not mean that a different type of those bacteria will have the same effect.

Let’s take breakdown the Lactobacillus acidophilus CL1285 variety, which happens to be one of the strains known to be effective in the treatment of Antibiotic-associated Diarrhea, into its three levels of classification.

Genus: Lactobacillus

Species:  acidophilus

Strain: CL1285

All three, but especially the strain, are important to identify whether or not the probiotic will have the intended health effect ( or that it has even be studied to have said effect).

Take a look at the following document if you want to learn a little bit more about which strains are associated with which conditions and products/foods.

Straining Over Strains: Antibiotic-associated Diarrhea

Antibiotics are commonly prescribed drugs and diarrhea is a common and unpleasant side effect of antibiotic usage (known as AAD, antibiotic-associated Diarrhea).

Parallel supplementation with probiotics, prior to commencing antibiotic treatment, may help reduce symptoms, but only if the correct strains are used.

(Consult your health care provider for more details on that relationship and appropriate usage)

For example,  McFarland et al found that  certain types of Lactobacillus ( including acidophilus CL1285, casei LBC80R, rhmanosus CLR2, csei DN114001 and reuteri 55730) are effective in resolving AAD, but other Lactobacillus strains are not.

Are Probiotics Safe?

If you are generally healthy, you can expect minimal or no ill health effects from probiotic use. Some people may experience gas but otherwise probiotics are considered quite safe.

Pregnant women, infants and those who are severely ill or with compromised immune systems should consult a physician before pursuing probiotic supplementation

Beyond Digestive Health

Now that we’ve tackled the bulk (pun intended) of the of the material surrounding probiotics and digestive health, let’s discuss the influence they may or may not have on other popular health concerns.

There is a massive amount of research in this area, so I’ve chosen to highlight a few key areas.


There is evidence to suggest that in imbalance in gut bacteria populations (known as dysbiosis) may be a hallmark of PCOS sufferers.

If you want to learn more about the connection between probiotics and PCOS management, read my article on the subject.

Atopic Dermatitis

Specifically for young children suffering with moderate to severe Atopic Dermatitis, the L fermentum VRI-003 PPC strain may help with symptoms.


The studies don’t appear to be the best, but there is some evidence that probiotic supplements may offer some decrease in anxiety related values in people with anxiety.

There is more work to be done to determine the strain, dosages and durations before firm conclusions can be drawn.

If you’d like to learn more about the connection between nutrition and anxiety, please do read my comprehensive article on the subject.

Weight Loss

Despite what you may have read online, and the potential differences in SCFA content of the gut between people of different weights, there is little evidence to support the notion that probiotic supplementation supports weight loss.

Type 2 Diabetes

Emerging evidence suggests a potential supportive role for probiotic supplementation in optimizing metabolic health for those who are living with type 2 diabetes.

If you have newly diagnosed type 2 or prediabetes, my article on lowering your A1C will help.

Final Thoughts

Let’s close this discussion by briefly coming back to the food vs supplement debate as it relates to probiotics.

The Supplement Vs Food Debate

So I’ve alluded to the fact that food pretty much always beats supplements unless there is a very specific need and proven benefit to be had, in which case supplementation offers a more efficacious alternative.

I offered some insight into those specific contexts throughout the article.

It’s obvious that, for day to day purposes,  a varied, balanced and nutrient  diet including whole foods containing pre and probiotics are a superior choice for the maintenance of gut and overall health for otherwise healthy people.

Rad et al sum it up nicely   “Foods may be preferred to supplements when public health promotion is aimed.”

Until next time,

Andy De Santis RD MPH