A full guide to probiotics from a dietitian 

a jar of yogurt with fruit and mint

If you’ve ever struggled with post-meal gassiness, needed to change to stretchy pants, or your gut just felt a bit off, you’ve probably thought about adding probiotics to your routine. But with all the different strains, dosages and … wait, do I need to keep these in my refrigerator? Your search can quickly start to feel a bit overwhelming. Well, fear not!  

We’re here to help you find your perfect match. Here’s a guide with everything you need to know about probiotics:  

First, why do you need a probiotic? 

First things first, ask yourself: what are your health goals? Better digestion, skin health, sleep or immune health? Different probiotic strains support different areas of your health, so it’s important to start by identifying the health concern you’re looking to address and then you can start narrowing down your probiotic by strain. Still feeling overwhelmed? Don’t worry—we got you!  

Some common probiotic strains and species: 

  • Bifidobacterium animalis: If you’re struggling with regularity and need some help unclogging those bowels (yeah, there are probably nicer ways to say that) try a probiotic with this strain. This species is best known to help with occasional diarrhea, constipation (no more sending memes from the toilet!) and other types of common digestive woes. Plus, it also plays an important role in supporting the immune system and preventing infections within the GI tract.1  
  • Bifidobacterium breve: A glam squad that lives in your gut? Sign us up! Beauty and skin health starts from within, and this species promotes better hydration and elasticity in your skin. And similar to B. animalis, Breve can also provide digestive relief by aiding with the breakdown of food, specifically fiber, making it easier to digest.2 
  • Bifidobacterium longum: When life gets tough, it’s time to look inward—to your gut that is. Stress can impact all parts of life, including digestion and sleep so addressing it is essential. The longum species not only helps improve gut health, but also plays a vital role in aiding your body’s stress response for better zZz’s.3 
  • Lactobacillus acidophilus: If you’re a lover of fermented foods like yogurt, kombucha, or kefir, then you likely have some of this strain taking up residence in your belly. And good on you, because it doesn’t just promote healthy digestion but also helps support everyday wellness. And if kombucha isn’t your favorite, don’t worry. Lactobascillus acidophilus isn’t just found in foods, it’s also naturally found in your mouth and GI tract.  
  • Lactobacillus reuteri: Yes, you can have it all! Well, at least you can come close to it with this strain of probiotic. It delivers great all-around support. Its benefits extend to your immune system, skin health, and digestive health.5 
  • Lactobacillus rhamnosus: Also living naturally in your gut, this helps reduce the risk for some GI infections, helps with occasional diarrhea and plays an important role in vaginal health. Some fermented foods contain L. Rhamnosus including some yogurts, kefir and certain cheeses.6 

Other (less common) types of probiotics: 

  • Saccharomyces boulardii (S. boulardii ): is a nonpathogenic yeast used to support the GI tract and promote regularity. 
  • Soil-Based Probiotics (Bacillus strains): are bacteria naturally found in the earth (soil). These are great for supporting the immune system, diversifying the microbiome and promoting GI health. 

Let’s talk CFUs 

Why does everyone keep talking about CFUs? Is that like an NFT or something? Not quite. It’s the unit we use to measure the dose of a probiotic. Here are the deets:  

CFU stands for colony forming units, which is the measure of alive and active microorganisms that are in the supplement. And probiotic doses can range from 5-100 billion CFUs. While we’re often told the higher the CFU, the better or more potent the probiotic – this isn’t always the case.  

What’s matters most is to check the probiotic you’re getting guarantees the potency (CFU amount) from the time of manufacturing to the time you take it.  

Pay close attention to the label as the manufacturer usually mentions something similar to “Formulated to contain 20 billion CFUs and delivers a minimum of 10 billion CFUs through best buy date” meaning it could contain anywhere from 10-20 billion CFUs depending on when you take it. 

Storing your Probiotics 

Listen, we know about all the houseplants you’ve killed, but keeping your probiotics alive is your shot at redemption. Trust us- it’s easy!   

There are a few factors that affect their survival rate, including the moisture content, temperature and pH of their environment. So, storing your probiotics properly is vital. Also, the type of strain and species of probiotics you’re taking also makes a difference. Some probiotics are shelf-stable and do not need to be refrigerated, while others do.  

But back to the easy part: most manufacturers provide care, we mean storage instructions for your new gut friends right on the packaging, so read those labels!  

Pro tip: store it in its original packaging, this often best ensures it’ll last until the expiration date. 

Do Probiotics Expire? 

In short: Yes. Like everything else you eat, always look for the manufacturing date or expiration date. After this date, the potency on the bottle can no longer be guaranteed and you’re probably not getting all the benefits. Generally, probiotics are often good for two years from the manufacturing date but check with the manufacturer if that information is unclear. 

Things to remember:  

  • Consider the reason why you are looking for a probiotic 
  • Look into the type of strains and species that most support your needs 
  • Check for the CFUs, expiration/best buy date and storage instructions 

What are some lifestyle tips to lessen post-meal gas? Read 8 tips to help reduce gas and bloating.

About Holly:

Holly is a Licensed Registered Dietitian with her Bachelor of Science in Dietetics from Michigan State University and completed her supervised practice program at Cal Poly San Luis Obispo. Holly’s goal is to inspire and empower others that living a healthy life is not only easy and enjoyable but attainable to all!

Do you have questions about supplements? Reach out to one of our experts, or take Persona’s free nutrition assessment, and learn exactly what you need to take your wellness to the next level.    

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.     

This information is not intended as a substitute for the advice provided by your physician or other healthcare professional, or any information contained on or in any product label or packaging. Do not use the information from this article for diagnosing or treating a health problem or disease, or prescribing medication or other treatment. Always speak with your physician or other healthcare professional before taking any medication or nutritional, herbal, or homeopathic supplement, or using any treatment for a health problem. If you have or suspect that you have a medical problem, contact your health care provider promptly. Do not disregard professional medical advice or delay in seeking professional advice because of something you have read in this article.       


  1. Jungersen M, Wind A, Johansen E, Christensen J, Stuer-Lauridsen B, Eskesen D. The science behind the probiotic strain bifidobacterium animalis subsp. lactis BB-12®. Microorganisms. 2014;2(2):92-110. doi:10.3390/microorganisms2020092 
  2. Natividad JM, Hayes CL, Motta J-P, et al. Differential induction of antimicrobial REGIII by the intestinal microbiota and Bifidobacterium breve NCC2950. Applied and Environmental Microbiology. 2013;79(24):7745-7754. doi:10.1128/aem.02470-13 
  3. Wong CB, Odamaki T, Xiao J-zhong. Beneficial effects of Bifidobacterium longum subsp. longum BB536 on human health: Modulation of gut microbiome as the principal action. Journal of Functional Foods. 2019;54:506-519. doi:10.1016/j.jff.2019.02.002 
  4. Homayouni A, Bastani P, Ziyadi S, et al. Effects of probiotics on the recurrence of bacterial vaginosis. Journal of Lower Genital Tract Disease. 2014;18(1):79-86. doi:10.1097/lgt.0b013e31829156ec 
  5. Mu Q, Tavella VJ, Luo XM. Role of lactobacillus reuteri in human health and diseases. Frontiers in Microbiology. 2018;9. doi:10.3389/fmicb.2018.00757 
  6. Segers ME, Lebeer S. Towards a better understanding of lactobacillus rhamnosus GG – host interactions. Microbial Cell Factories. 2014;13(Suppl 1). doi:10.1186/1475-2859-13-s1-s7 

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