Humans have used probiotics for over 10,000 years.1 Likely discovered by accident,Although there's no specific evidence to support humans' first usage of probiotics, most researchers agree that they were likely created purely by accident when our ancestors traversed high-temperature deserts carrying milk in bags made from sheep stomachs. The naturally-occurring probiotics in these bags changed the flavor of the milk inside, just like yogurt and cheese today. These changes conferred noticeable health benefits and extended preservation, making them a staple for civilizations worldwide since ancient times. our understanding of their extensive benefits has grown exponentially in modern times.

The vast majority of our immune systems — 70% — resides in our gut.2 Unfortunately, the delicate balance of our gut microbiome,The human body contains more bacterial cells than human cells. In fact, the ratio is 10-1. Our microbiome is the collection of good and bad bacteria in our gut. Keeping a healthy balance of good bacteria can have huge benefits not only for our digestion, but our brain, skin, immune system, and a host of other functions. can be thrown off by simple everyday things beyond our control — stress, pollution, lack of sleep, or food. 

Probiotics hold the key to balancing the gut microbiome and strengthening our immune system. They protect our bodies from dangerous pathogens, promote energy, enhance mood, and enrich our health in numerous ways. 

Not all probiotics are equal, so Smarter Reviews delved into the research for this popular category. We'll break down how to identify a potent supplement and show you our Top 5 Probiotic Supplements on the market today.

A Brief History of Probiotics

Records and artifacts show that probiotics and fermented foods have been used since ancient times. 

7,000 B.C. — Ancient Egyptians accidentally created fermented milk products. With noticeable health and preservation qualities, these cheeses, yogurts, and butters became widely used.3

1300 B.C. — Fermented milk offered to God in The Bible — “Abraham offered to God, showed in an oak wood, fermented milk” (The Bible, Genesis 18, 1–8).

1908 AD — Nobel-prize winner and The Father of Cellular Immunology — Ilya Mechnikoff theorizes that the friendly bacteria in yogurt could improve physical and mental health.4  

1935 — First commercial probiotic, Yakult, a fermented milk product, released in Japan.5

2001 — The World Health Organization establishes a definition for probiotics, "live microorganisms, which when administered in adequate amounts, confer a health benefit on the host.6

2019 —Global probiotics supplement market tops $40 billion annually.7

Despite their popularity over the centuries, research into probiotics has taken a dramatic leap within the last 40 years. We now know that there are hundreds of different probiotic strains, and they all perform different functions within our bodies. Some strains enhance our digestive systems, minimizing symptoms like diarrhea or constipation. Some promote clear, glowing skin or healthy hair. Others enhance our mood, energy, or mental clarity. And still others enhance our immunity.

Top Probiotic Strains & Their Benefits:

When it comes to choosing a high-quality probiotic supplement, strain selection is just one factor to consider. Potency, viability, CFU, and clinically studied strains all play a significant role in determining health benefit.

What To Avoid When Choosing a Probiotic

Limited Strains

Many supplements only contain one or only a few different probiotic strains. Probiotics strains all serve different purposes within the body, so a product with just a few strains limits the overall effectiveness our health. Probiotics supplements offering a more comprehensive approach  provide a more substantial and longer term impact on our health and immunity. Look for a supplement with at least 9 individual strains.

Probiotics Without Clinical Studies

When you look at the label of a high-quality probiotic supplement, each strain will list a series of letters and numbers following the strain name, such as La-14. This indicates the DNA sequence of a particular strain has been identified. These series provide a useful tool for consumers to evaluate whether clinical studies exist behind a particular strain. 

Many probiotic formulations do not list their specific substrains. This suggests the brand may be using generic (and cheaper) strains that have not been clinically studied. For optimal results, select a probiotic supplement with substrains listed.

Refrigerated Probiotics

Refrigerated products can be damaged during shipping. They also may lack the hardiness to survive the hot, acidic conditions in our gut. We suggest choosing a probiotic that is well-formulated to withstand room temperature and does not require being refrigerated during periods of non-use.

4 Secrets of A Good Probiotic

Based on our research and feedback from our Smarter Shoppers, these are the things to look for in an exceptional probiotic supplement:

High CFU Count

Since our microbiome is composed of about 100 trillion good and bad bacteria, a high number of Colony Forming Units (CFUs) will have greater impact on the growth of beneficial bacteria within our gut.23 It's essential to choose a probiotic which specifies CFU versus "active cultures" or "live cultures." Look for a formula with a minimum of 40 billion CFU.


The latest research shows that fiber-based prebiotics (such as NutraFlora Fiber) feed the probiotics, helping them to populate and flourish in our gut.24 Choose probiotics supplements containing prebiotics to significantly increase the overall effectiveness of the probiotic.

Clinically Studied Strains

There are hundreds of different probiotics strains, but many have never been proven effective. The best way to identify the potency of a particular strain is to look at the clinical studies backing it up. To find out if a particular strain has clinical backing, search the strain name on the internet. Look for strains proven effective by clinical studies

Formulated By A Doctor

It takes specific expertise to form an effective probiotic formulation. More is not necessarily better. The exact combination of strain type, potency, quantity, and prebiotics determines the product's quality. Look for real doctors specializing in gut health backing the product.

Top 5 Probiotic Supplements of 2021

We've compiled a list of what we've found to be the top five products in this category, on the market today.

Click to see the list of probiotics we evaluated >>