TL;DR (for top of article)

  • Nearly 80% of the immune system lives in the gut, so maintaining healthy intestinal bacteria supports overall immunity.

  • Probiotic supplementation has been shown to reduce respiratory infections, lower allergy risk in infants, and enhance gut defense against harmful bacteria like H. pylori.

  • Clinical research suggests probiotics may help with athletic recovery, eczema prevention, and ulcer protection — though product choice and strain matter.

  • Probiotics and the Immune System

    Nearly 80% of your immune system resides in your gut, so the benefits of probiotics should come as no surprise. They’re useful for many conditions — from allergies to ulcers and even the common cold — and their influence extends far beyond digestion.

    Your Gut: An Immune Ecosystem

    Your colon is an ecosystem containing several pounds of bacteria that belong there. These friendly microbes remove toxins, keep pathogens in check, and create nutrients that nourish your intestinal lining and immune system. Many studies show that probiotic supplementation supports this immune balance.

    Probiotics Reduce Respiratory Infections

    Researchers studied 58 athletes taking Lactobacillus casei Shirota for 16 weeks. The placebo group had 36% more upper respiratory infections (URTI). The authors concluded that regular probiotic intake may reduce infection frequency and support immune resilience during training [1].

    Probiotics Support Infant and Childhood Immunity

    Taking probiotics during pregnancy and infancy can lower the risk of allergic dermatitis (eczema).
    A 2011 meta-analysis of 14 studies found probiotics help prevent atopic dermatitis [2], and this was reinforced by a 2023 systematic review [3].

    Probiotics Help Combat H. pylori

    Helicobacter pylori is linked not only to ulcers but also to cancer and autoimmune diseases.
    In one study, 13 out of 40 subjects taking probiotics cleared H. pylori within a month [6]. When used alongside standard therapy, probiotics increase eradication rates and reduce side effects [7]. Read more research about probiotics and H. pylori.

    Probiotics and Infant Gut Health

    In 2012, a double-blind study of 31 low-weight infants found probiotic supplementation increased intestinal blood flow [4].
    Later research confirmed that probiotics can help prevent necrotizing enterocolitis (NEC) in preterm infants [5].
    However, in 2023 the FDA issued a warning about probiotic use in hospitalized preterm infants due to rare infections; no probiotic is FDA-approved for this use.

    The Takeaway

    Probiotics influence far more than digestion. They support immune function, may reduce infections, and help regulate inflammation from the gut outward. The key is balance — both in the microbiome and in choosing clinically studied strains.

References:

 

  1. International Journal of Sports Nutrition, Exercise and Metabolism(2011 Feb; 21(1): 55-64) Daily probiotic’s (Lactobacillus casei Shirota) reduction of infection incidence in athletes
  2. Epidemiology(23(3):402-414, May 2012 Probiotics supplementation during pregnancy or infancy for the prevention of atopic dermatitis: a meta-analysis
  3. Transl Pediatr. 2023 Apr 27;12(4):731–748. The effect of probiotics in the prevention of atopic dermatitis in children: a systematic review and meta-analysis
  4. Journal of Perinatology(33, 40-44 doi:10.1038/jp.2012.37) Probiotics supplementation increases intestinal blood flow velocity in extremely low birth weight preterm infants
  5. Cochrane Database 26 july 2023 Probiotics to prevent necrotising enterocolitis in very preterm or very low birth weight infants
  6. Inflammation & Allergy–Drug Targets (Volume: 11, Issue: 3, Year: June 2012, Pages: 244-249)
  7. Scientific Reports Published: 02 May 2024 The effects of probiotics supplementation on Helicobacter pyloristandard treatment: an umbrella review of systematic reviews with meta-analyses