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Bubbles on a green drink representing probiotics in the gut

What are Probiotics? Types, Functions, and How They Work

Reviewed by: Trevor Kirby, PhD, Principal Research Scientist, Research
4 MIN READ — 5 Citations — 06/09/2026

Probiotics help your body in more ways than just gut health. Here, we’ll go into what they actually are, how they work, and why consuming them daily makes a difference for your overall health.

Key Takeaways

  • 01.

    Probiotics are beneficial bacteria that support overall microbiome balance.

  • 02.

    The benefits of a balanced gut microbiome include digestion and nutrient absorption, and extend to immune function and even improved mood and energy levels. So it’s beneficial to prioritize adding probiotics into your daily health routine.

  • 03.

    Diet and lifestyle play a major role in gut health: consuming probiotic-rich foods like fermented foods, along with fiber-rich prebiotics, helps maintain your microbiome’s balance.

  • 04.

    Targeted supplements such as AG1 are also a good source of probiotics. AG1’s formula contains probiotics and prebiotics to support your gut health.

A healthy gut microbiome is essential for digestion, immune function, and overall well-being. But modern lifestyle and diet habits can disrupt the balance of the gut microbiota. This makes it especially important to support your gut health—and that’s where probiotics come in.

What are probiotics, and what do probiotics do?

Probiotics are gut-friendly live microorganisms, more commonly referred to as beneficial bacteria. They help maintain a balanced gut microbiota, which specifically supports digestive health and gut function.

Which foods have probiotics?

Fermented foods with live cultures contain the most natural probiotics. Probiotics are found in foods such as yogurt, kefir, sauerkraut, kimchi, miso, tempeh, apple cider vinegar (if it contains “the mother”), and kombucha. They can also be consumed through supplements. Consistent consumption of these foods will help introduce beneficial microbes to your gut and support your microbial diversity.

How do prebiotics fit in?

Probiotics do best when supported by prebiotics.

While probiotics are live bacteria, prebiotics are not bacteria; they are the substances that the probiotic bacteria then ferment in the colon. This fermentation produces short-chain fatty acids that help support gut lining integrity. Prebiotics are abundant in fiber-rich plant foods, and taking prebiotic supplements can help if your diet is low in fiber.

In other words: Prebiotics feed beneficial bacteria, helping probiotics work more effectively, sustaining long-term gut health.

The benefits of probiotics

There are compounding benefits that come with taking probiotics. Feed your gut an adequate supply of probiotics, and the benefits throughout the body compound.1,2

  1. Probiotics help maintain microbial balance in the gut, supporting the body’s digestion and nutrient absorption.
  2. Probiotics support the integrity of the intestinal lining—also known as the gut barrier. This plays a role in the body’s natural defense processes.3
  3. Probiotics help maintain immune system function by interacting with immune cells in the gut.
  4. Probiotics influence immune memory and tolerance. Research shows that a properly functioning gut microbiota plays a role in supporting normal immune system function.4

Dive deeper into the specific benefits of taking probiotics here.

How can you tell if you need probiotics?

People usually only consider probiotics when experiencing discomfort and bloating, with bloating being a more common motivator for probiotic use.5

But even if you don’t experience discomfort, habits like consuming alcohol, sugar, or highly processed foods can dismantle your gut’s balance of healthy bacteria. Incorporate probiotics in your diet, along with healthy, gut-friendly foods, to set your body up for success.

How to choose the right probiotic supplement

No one probiotic supplement is right for every individual. Effectiveness can vary for each person’s unique health, and different strains target different digestive concerns. Choose research-backed probiotics—and pair them with prebiotics—to aim for the best gut health results.

AG1 Next Gen’s research-backed formula is designed to offer probiotic support for your gut. It contains 37mg (10 billion viable cells)† of the strains Lactobacillus rhamnosus GG, Lactobacillus acidophilus NCFM, Bifidobacterium lactis HN019, Lactobacillus casei LC-11, and Lactobacillus plantarum LP-115.

AG1 Next Gen also includes a prebiotic complex (with ingredients like apple powder and inulin), intended to work alongside our selected probiotic strains to promote the growth of healthy bacteria.

How to support overall gut health

Remember that gut health is best supported by a mix of probiotics and prebiotics. (Find our full Gut Health Guide here.) Here is a list of things to consume to preserve an active, diverse microbiome:

  1. Diverse, whole-food diet
  2. Prebiotic fiber
  3. Fermented foods with live cultures
  4. Limited gut disruptors like alcohol, excess sugar, and ultra-processed foods

If you’re looking for a comprehensive supplement that includes probiotics, AG1 Next Gen is a great start. Our formula is clinically studied and designed to support your overall health, and that includes gut health and the microbiome. Alongside its broad range of other necessary nutrients, it intentionally includes prebiotics, probiotics, and digestive enzymes—plus greens, vitamins, and minerals—all in one simple scoop. In other words, a daily health drink gets you your essential nutrients while also helping create, restore, and maintain your gut flora.

References:

  1. Khalesi S, Bellissimo N, Vandelanotte C, Williams S, Stanley D, Irwin C. A review of probiotic supplementation in healthy adults: helpful or hype?. Eur J Clin Nutr. 2019;73(1):24-37. doi:10.1038/s41430-018-0135-9
  2. Merenstein DJ, Tancredi DJ, Karl JP, et al. Is There Evidence to Support Probiotic Use for Healthy People?. Adv Nutr. 2024;15(8):100265. doi:10.1016/j.advnut.2024.100265
  3. Zheng Y, Zhang Z, Tang P, et al. Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials. Front Immunol. 2023;14:1143548. doi:10.3389/fimmu.2023.1143548
  4. Zhou P, Chen C, Patil S, Dong S. Unveiling the therapeutic symphony of probiotics, prebiotics, and postbiotics in gut-immune harmony. Front Nutr. 2024;11:1355542. doi:10.3389/fnut.2024.1355542
  5. Lynch E, Troob J, Lebwohl B, Freedberg DE. Who uses probiotics and why? A survey study conducted among general gastroenterology patients. BMJ Open Gastroenterol. 2021;8(1):e000742. doi:10.1136/bmjgast-2021-000742
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  1. In a triple-blind, randomized, placebo-controlled parallel-designed clinical trial evaluating nutrient biomarkers and microbiome shifts in 105 healthy adults ages 20-59 over the course of 12 weeks using the AG1 Next Gen formula.
  2. In a double-blind, randomized, placebo-controlled 2-week crossover clinical trial assessing nutrient gaps and microbiome shifts in 20 active adults ages 19-37 using the AG1 Next Gen formula.
  3. In a double-blind, randomized, placebo-controlled 2-week crossover clinical trial assessing nutrient gaps and microbiome assessments of 40 healthy adults with occasional GI distress ages 26-59 over the course of 4 weeks using the AG1 Next Gen formula.
  4. In a double-blind, randomized, placebo-controlled crossover clinical trial assessing nutrient gaps and bioavailability in 16 healthy adults ages 18-42 over the course of 8 hours using the AG1 Next Gen formula.
  5. In a third-party, single-arm, closed label interventional study of 104 healthy adults ages 25-59 assessing self-perceived efficacy of AG1 Next Gen over 3 months.

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