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In today’s hectic world you may feel stressed, eat processed foods to make mealtimes easier, or fall sick and need antibiotics. Unfortunately, this can hurt the good bacteria in your gut. Fortunately, taking a probiotic is one way to improve your gut health.

It can feel like you need a biology degree and a firm understanding of Latin to figure out how to pick the best probiotic. With ingredients like Lactobacillus and Bifidobacterium and acronyms like CFU, it's easy to get overwhelmed. So, we are breaking down the science and technical language and creating a guide to select the best probiotic.

Please note that you should consult with your health care provider before starting probiotic supplements, especially if you are immunocompromised, had a recent illness or surgery, are currently taking antibiotics, or have been told to monitor your vitamin K intake. Your health care provider can also help you select which one is right for you and check for potential interactions with any prescription medicine you may be taking.

Probiotics are a type of supplement that you can take to add beneficial bacteria and other live microorganisms to your digestive system. These tiny organisms and their genetic material make up what is called our gut microbiome. They help your digestive system break down the food you eat and create essential vitamins and nutrients that help boost your immune system, and support urinary tract and vaginal health.

Different strains of probiotics impact our gut health in different ways. Probiotics can be used to relieve or manage symptoms of bloating, constipation, lactose intolerance, eczema, acid reflux and diarrhea. New research is also beginning to link how our gut microbiome connects to our mental health.

You can also take prebiotics and postbiotics. Prebiotics are certain natural fibers and other substrates that cannot be digested or absorbed in the stomach or small intestine. “If a probiotic is adding the good bacteria, prebiotics are feeding the good bacteria,” says Dan Greenwood, Ph.D., RD, a clinical nutrition expert and the former president of the Minnesota Academy of Nutrition and Dietetics. Postbiotics are the result of probiotics eating prebiotics. Postbiotics are also essential members of the gut microbiome and help our immune system. Symbiotics are a type of supplement that combines probiotics and prebiotics.

There are natural sources of probiotics and prebiotics. Fermented foods like some dairy products, including yogurt, cottage cheese, buttermilk, or kefir, and sauerkraut, kombucha and kimchi are high in probiotics. However, Greenwood says, “If you’re going to take a probiotic, try to eat a diet high in prebiotics.” You can naturally source prebiotics like inulin and pectin from asparagus, onions, whole wheat, oats and foods with skin on them, like oranges, beans and brown rice. Greenwood also adds that “getting away from processed foods is one the best ways to improve our microbiome.”

Things like stress, taking an antibiotic, eating processed foods, getting sick, and aging can hurt the good bacteria in your gut. Some signs that your gut bacteria are imbalanced include bloating, constipation, diarrhea or irritable bowel syndrome (IBS). Fortunately, taking a daily probiotic can help increase the number of good bacteria in your gut.

Check with your doctor before taking a probiotic for symptom relief; you don’t want to mask signs of something more serious.

A probiotic can also be good even if you aren’t feeling any discomfort. “As an athlete, you may want to maintain a high level of health to perform your best,” says Kristen Williamson, RD, LDN, CPT, a registered dietitian and certified personal trainer.

Ask yourself the following questions to help select the right probiotic for you.

Understanding why you want to take a probiotic can help you pick which probiotic is best for you based on which strain of bacteria is in it. Probiotic names can be long and confusing. Think back to high school biology class. Each name refers to the genus, species, subspecies (may or may not have this), and strain designation (usually a number) in that order. The most commonly studied probiotic genera (plural form of genus) are Lactobacillus and Bifidobacterium. Knowing the full name of the strain in probiotic, prebiotic or symbiotic can help you research and see if you are taking the right one to meet your goal.

For example, are you looking to increase your health in general, or do you want something to help with constipation or diarrhea?

Here is a list of some strains and how they may help you:

Probiotics are currently not regulated by the Food and Drug Administration, which means quality and purity testing are not required because probiotics are not intended to prevent, treat or cure disease. But there are other ways to measure quality. Look for reputable brands and probiotics that say they are third-party reviewed and tested. For example, the label may say that the probiotics are manufactured in cGMP (Current Good Manufacturing Practices) certified facilities. A cGMP certification means that manufacturers evaluate their ingredients' identity, purity, strength and composition.

Some companies will also list where their ingredients are sourced. You will want to select something that says ‘traceable’ or ‘DNA identified.’ This means that the strains are verified and come from quality sources. Does the manufacturer do clinical tests on the strains or discuss using clinically tested strains? Different strains have different functions, so you will want to select a strain that is proven to be beneficial.

Last, check the expiration date. If the date has passed, the probiotic likely won’t be as potent as the label claims. Bacteria only live for so long, so many probiotic companies only guarantee their products until the ‘best if used by’ date.

Bacteria are sensitive to temperature. Some strains must be refrigerated, while others are considered ‘shelf stable’ and are safe to store at room temperature but out of direct sunlight. If you plan on taking them while you are away from home, you may want to consider a shelf-stable probiotic. Just know that “be it fridge or shelf-stable, that doesn’t make one better than the other,” says Williamson.

Colony-forming units (CFUs) measure the number of viable colonies or cells in each dose. This number is usually in the billions and can range from one to over 100 billion. But don’t be tricked into buying a probiotic because it has more CFUs than another product. The desired number of CFUs, “depends on what you are looking to do and how the probiotic may assist you…if you are treating something [specific], you may need a higher dose,” says Williamson. Talking with your health care provider or reading clinical studies about a specific strain can help you determine how many CFUs may be necessary.

You also need to be mindful of how many probiotics you are getting naturally from foods like yogurt or cottage cheese. If you regularly consume foods high in probiotics, you likely won’t need a probiotic with high CFUs.

Also, be sure to check the label. Listing CFUs by a ‘best by’ date means there should be that many CFUs at the time of expiration. Listing CFUs by ‘at the time of manufacture’ means the CFUs are only guaranteed when the product is made. Because bacteria can be sensitive to temperature and time, the number of CFUs you receive may be less than what is on the bottle.

For probiotics to work, they need to get to your gut or your intestines. This means they need to be able to survive the stomach's acidic environment, which can kill the bacteria in probiotics. Look for probiotics that have specially formulated capsules or use acid-resistant strains of bacteria.

Read online personal reviews, but be cautious. How people respond to probiotics varies. “People have different reactions to different probiotics,” says Williamson. So what works or didn’t work for one person may or may not work for you. “You [may] need to test out a couple of different ones. Pay attention to strain and count; it may take a few to find one that works for you,” Williamson adds.

Ritual Synbiotic+ is a synbiotic product, meaning it contains a prebiotic and probiotic, but as a bonus, it also includes a postbiotic to optimize your gut health. Using a delayed-release capsule makes it more likely that the probiotic survives the stomach acid. The website claims to help with bloating, gas, diarrhea, and support the immune system and gut barrier function.

Strains: Prebiotic: Prebiotic PreforPro Probiotic: Lactobacillus rhamnosus (LGG) and Bifidobacterium anamalis ssp. Lactis (BB-12) Postbiotic: Corbiome® Tributyrin CFUs: 11 billion CFU Directions: Taken once daily, with or without food Quality: According to the manufacturer, all products are third-party tested for quality, purity, and strength. All ingredients are made traceable, so you know where geographically everything is sourced. Probiotic is vegan and gluten-free. Storage: Shelf-stable and comes in a moisture-controlled bottle Cost: $50 for 30 pills. All subscriptions include free shipping, you can cancel anytime, and you receive a money-back guarantee. You can also rush or delay an order from your account.

Buy Ritual Synbiotic+ (ritual.com)

RenewLife 50+ probiotic is specially designed to counteract the changes to your gut bacteria that happen with age. “As you age, bifidobacteria decreases, so you need more of that,” says Greenwood, a key strain in this probiotic. The delayed-release capsule promotes regularity and supports digestive balance and immune and respiratory health.

Strains: Lactobacillus rhamnosus GG, Bifidobacterium lactis Bi-07, Bifidobacterium lactis HN019, Lactobacillus acidophilus NCFM, Lactobacillus paracasei Lpc-37, Bifidobacterium infantis Bi-26, Lactobacillus acidophilus La-14, Bifidobacterium lactis BI-04, Lactobacillus brevis LBr-35, Lactobacillus casei Lc-11, Lactobacillus lactis Li-23 and Lactobacillus plantarum Lp-115 CFUs: 30 billion Directions: Take once daily with or without food. Quality: Probiotics are third-party tested and have DNA verification for most strains. Probiotic is non-GMO probiotic that is free of gluten, dairy and soy. Storage: Store at 77F (25C) or below. Best if refrigerated. Cost: $22.49/ 30 capsules

Buy RenewLife 50+ Probiotic (renewlife.com)

Jarrow Formulas Jarro-Dophilus EPS (enhanced probiotic system) uses a unique ‘EnteroGuard’ coating to ensure that its proprietary blend of probiotics can survive the stomach acid and make it to the intestines. Their website claims the probiotic aids in supporting intestinal and immune health.

Strains: Lacticaseibacillus rhamnosus R0011, Lactobacillus helveticus R0052, Pediococcus acidilactici R1001, Lacticaseibacillus casei R0215, Bifidobacterium longum BB536, Lactiplantibacillus plantarum R1012, Bifidobacterium breve R0070 and Lactococcus lactis subsp. lactis R1058 CFUs: 5 billion Directions: Take one capsule up to four times daily, preferably on an empty stomach. Quality: According to Jarrow Formulas, their raw material suppliers and products are manufactured in cGMP-certified facilities. Storage: Shelf-stable at 77 degrees and come in blister packs Cost: $32.55/ 120 capsules

Buy Jarrow Formulas Jarrow-Dophilus EPS (swansonvitamins.com)

Garden of Life Dr. Formulated Probiotics Once Daily is a probiotic with a prebiotic supplement that uses stomach acid-resistant strains that claim to support digestive health and regularity. The Garden of Life also claims to be the first supplement company to be certified carbon-free.

Strains: Prebiotic: Acacia (A. Senegal) fiber Probiotic: Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus gasseri, Lactobacillus paracasei, Lactobacillus bulgaricus, Lactobacillus brevis, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus salivarius, Bifidobacterium lactis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium, infantis, Bifidobacterium longum CFUs: 30 billion Directions: Take once daily with or without food. You can also open the capsule, mix it with water or juice, or put it on food. Quality: It is a certified non-GMO and gluten-free product. It is also dairy-free, soy-free and vegetarian. Storage: Must refrigerate after purchasing Cost: $23.51/ 30 capsules

Buy Garden of Life Dr. Formulated Probiotics Once Daily (swansonvitamins.com)

NOW is a US-based family-owned and operated company that started as a local health food store. This probiotic also supports immune function and a healthy gut.

Strains: Lactobacillus acidophilus (La-14), Bifidobacterium lactis (Bl-04),Lactobacillus plantarum (Lp-115), Lactobacillus casei (Lc-11),Lactobacillus rhamnosus (Lr-32), Lactobacillus paracasei (Lpc-37),Bifidobacterium breve (Bb-03), Streptocous thermophilus (St-21),Lactobacillus salivarius (Ls-33), and Bifidobacterium longum (BI-05) CFUs: 25 billion Directions: Take one capsule up to twice daily. Quality: According to the manufacturer, the product has an ‘A’ rating with the National Product Association (NPA), the first association to offer the GMP certification. The probiotic strains are also verified by ‘DNA-fingerprinting technology.’ Probiotic does not contain wheat, gluten, soy, milk, egg, fish, shellfish or tree nuts. Storage: Shelf-stable but must be refrigerated after opening. Cost: $24.99/ 100 capsules

Buy Now Probiotic-10 25 Billion (swansonvitamins.com)

Klaire Labs Ther-Biotic Pro IBS Relief is a medical food for managing IBS, including constipation, diarrhea and gas. Its medical food classification means that this product meets consumers' needs that cannot be met by just changing how they eat. It also means that this product should be used under the supervision of your healthcare provider. The products are encapsulated using a technology that protects the probiotics from stomach acid so they can reach the intestines.

Strains: Prebiotic: Partially hydrolyzed guar gum (PHGG) Probiotic: Lactobacillus plantarum, Lactobacillus acidophilus, and Bifidobacterium lactis Each capsule also contains 10 mg sodium and 10 mg potassium. CFUs: 20 billion Directions: Take once daily during the first part of a meal. Quality: Klaire Labs is a cGMP manufacturing facility. Probiotic is hypoallergenic, non-GMO and vegetarian Storage: Shelf-stable in a cool, dry place and away from direct light. The probiotic doesn’t need to be in the fridge, but storing it in the refrigerator extends its shelf life. Cost: $34.99/ 21 capsules

Buy Klaire Labs Ther-Biotic Pro IBS Relief (pharmaca.com)

The Bio-K Plus Daily Care 50 Billion Probiotic claims to be great for the person who wants general support or needs a stronger alternative. Their targeted release capsule can withstand stomach acid, so the probiotic is safely delivered to your intestines.

Ingredients: Proprietary strains of Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R and Lactobacillus rhamnosus CLR2 CFUs: 50 billion Directions: Take one capsule daily with or without food. Quality: The Bio-K Plus formula is Health Canada approved. The probiotic is vegan and free of hormones, antibiotics, pesticides, gluten and heavy metals. Storage: Room temperature Cost: $57.99/60 capsules

Buy Bio-K Plus Daily Care 50 Billion Probiotic (pharmaca.com)

The Metagenics Ultra Flora Control probiotic claims to help with weight loss when taken as part of a healthy diet and exercise regimen. “Probiotics are a tool in the toolbox; always [use them] in conjunction with a healthy diet,” says Greenwood.

Strain: Bifidobacterium lactis CFUs: 10 Billion Directions: Take one capsule daily. Quality: This product has in-house and third-party testing on every lot. You can also enter the lot number of your product to view quality testing information. Probiotic is non-GMO, gluten-free and vegetarian friendly. Storage: Shelf-stable, but stored below 75ºF Cost: $55.90/30 capsules

Buy Metagenics Ultra Flora Control (pharmaca.com)

How soon you see changes depends on why you are taking the probiotic. If you are taking a probiotic just to maintain your current health, you may not “feel” any changes, but that doesn’t mean it isn’t doing anything.

Because probiotics are considered a dietary supplement, their side effects are usually minimal. You may feel slight stomach discomfort unless you are immunocompromised or very sick. Probiotics are “low risk, high yield, and for some people, it could help quite a bit,” says Greenwood.

“Our gut doesn’t work in isolation,” says Williamson. When combined with a balanced diet and exercise, probiotics can improve your overall wellness journey. Picking the right probiotic for you is not just about the brand; it's selecting the right strain for you. You may need to check with your doctor before starting a probiotic regimen. “I think we are just dipping our toes into the world of probiotics [and we are] finding more out about it all of the time, I think there is a lot of potential [in probiotics],” says Williamson.

Prices are accurate and items in stock at time of publishing.

Dr. Nicole Loew PhD, RN and Co-Founder of Woman Centered Health, is a nurse researcher, podcaster and writer who works to put research in the hands of people who need it most. This author is writing sponsored content paid for by Pillar4 and not affiliated with Sports Illustrated.