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Did you know that a large portion of the immune system's cells are active in the gut microbiome?

Probiotics for immune health: How gut bacteria support immune function

Reviewed by: Trevor Kirby, PhD, Principal Research Scientist, Research
5 MIN READ — 6 Citations — 05/27/2026

You've likely heard about probiotics and gut health. But here's what you might not know: your gut health and immune system are deeply connected in several ways.

Key Takeaways

  • 01.

    A healthy gut is connected to a healthy immune system.

  • 02.

    Consistent consumption of probiotics helps maintain a healthy gut microbiome, which in turn fosters a healthy immune system.

  • 03.

    Probiotics help support a healthy immune system by contributing to gut barrier function and supporting normal immune signaling in the gut. They also help maintain a balanced gut environment and support normal immune responses.

  • 04.

    AG1's formula contains probiotics (as well as additional prebiotic compounds) to support your gut health—and with it, your body's overall immune health.

What are probiotics?

Probiotics are live microorganisms—often called beneficial bacteria—that help maintain a healthy balance of gut microbes and support the gut barrier.

As such, probiotics play a role in supporting healthy immune function. That's part of why AG1 Next Gen contains not just immune-supporting vitamins, minerals, and nutrients, but also clinically-backed strains of probiotics for a well-rounded approach to overall health.

How probiotics support immune function

Did you know that a large portion of the immune system's cells are active in the gut microbiome?1 This means that a healthy gut microbiome correlates with a healthy immune function. Probiotics are usually taken to address the former, but in doing so, they help the latter.

Here’s a little more about how probiotics help with immune function:

  1. They support the gut barrier: Probiotics help support the integrity of the intestinal lining, which plays a role in the body's natural defense processes.2
  2. They support immune signaling: As one review article puts it, “Probiotic bacteria can interact with intestinal immune cells and commensal microflora to support immune functions.”3 In other words, probiotics interact with immune cells in the gut to help support immune responses.
  3. They shape immune memory and tolerance: Recent scientific reviews show that a properly functioning gut microbiota plays a key role in supporting immune system tolerance and appropriate immune responses.4

Together, these probiotic-assisted actions help the immune system do its job without added gut-related stress. Basically, probiotics support immune system health by doing what they do best: supporting the gut.

Top probiotic strains for immune health

There’s no specific “immune support probiotic”. Benefits are often strain-specific, and their effectiveness can vary for each individual and your unique health.

Keep this in mind:

  • Not all probiotics are the same: different strains target different digestive concerns. You might want to speak with your doctor about what’s best for you.
  • Choose research-backed probiotics and pair them with prebiotics to aim for the best gut health results. (Prebiotics feed beneficial bacteria, helping probiotics work more effectively, sustaining long-term gut health.)
  • A diet that includes fermented foods (like yogurt, kefir, sauerkraut, and kimchi) provides diverse microbes.

AG1 Next Gen’s formula 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. It 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. The ingredients in AG1 Next Gen are carefully selected and research-backed, designed to offer the best support for not just your gut, but your immune health. In short, AG1’s formula supports your overall health with essential vitamins, minerals, nutrients, and probiotics.

Incorporating probiotics into your diet

Luckily, it’s easy to start getting probiotics into your diet or supplement routine. While mixing up a daily drink of AG1 will provide you with five strains of probiotics as well as prebiotics—all of which will contribute to your gut function—it can’t replace whole foods.

Here are some tips for adding probiotics to your meals:

  1. Eat fermented foods regularly. Many everyday foods contain live beneficial microbes, such as:
    • Yogurt
    • Kefir
    • Sauerkraut and kimchi
    • Miso and tempeh
    • Kombucha

      Aim to eat moderate and consistent servings of some of these throughout your week. Need ideas? Turn to yogurt for breakfast or a daily snack. Enjoy some kefir in the morning—balance its tart taste with bitter coffee, or vice versa—and pursue the occasional sauerkraut on a sandwich. Order miso soup with your sushi. And if it’s ever available, opt for kombucha instead of a soda or cocktail.
  2. Consider probiotic supplements. These can be helpful when your diet lacks fermented foods, when you’re traveling and don’t have access to probiotic-filled foods (and/or are consuming other gut-stressors), or are recovering from antibiotics.
  3. Feed probiotics with prebiotics. Probiotics thrive when paired with prebiotics, which are found in many foods, especially onions, garlic, leeks, bananas, oats, asparagus, and legumes. (This is why AG1’s formula contains prebiotics alongside probiotics.)
  4. Supplement with AG1. And of course, there’s a fourth tactic for easily incorporating probiotics into your diet: Enjoying AG1 every day. With 75+ vitamins, minerals, and whole-food-sourced ingredients, the formula is designed to support the immune system. But with its inclusion of probiotics and prebiotics, our supplement offers comprehensive support.

Probiotics are not intended to treat, cure, or prevent any disease. Rather, probiotics help support a balanced immune function by helping maintain a healthy gut microbial community, interacting with immune cells in the gut,5 and supporting gut barrier integrity (which is a key immune defense6).

Maintaining good gut health can help you achieve better immune health. Probiotics aren’t just for the gut; rather, they positively affect the whole immune system.

References:

  1. Wiertsema SP, van Bergenhenegouwen J, Garssen J, Knippels LMJ. The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies. Nutrients. 2021;13(3):886. Published 2021 Mar 9. doi:10.3390/nu13030886
  2. 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. Published 2023 Apr 24. doi:10.3389/fimmu.2023.1143548
  3. Mazziotta C, Tognon M, Martini F, Torreggiani E, Rotondo JC. Probiotics Mechanism of Action on Immune Cells and Beneficial Effects on Human Health. Cells. 2023;12(1):184. Published 2023 Jan 2. doi:10.3390/cells12010184
  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. Published 2024 Feb 8. doi:10.3389/fnut.2024.1355542
  5. Mazziotta C, Tognon M, Martini F, Torreggiani E, Rotondo JC. Probiotics Mechanism of Action on Immune Cells and Beneficial Effects on Human Health. Cells. 2023;12(1):184. Published 2023 Jan 2. doi:10.3390/cells12010184
  6. Takiishi T, Fenero CIM, Câmara NOS. Intestinal barrier and gut microbiota: Shaping our immune responses throughout life. Tissue Barriers. 2017;5(4):e1373208. doi:10.1080/21688370.2017.1373208
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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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