Choosing the right probiotic: What to look for

Probiotics are one of the most talked-about supplements today, often promoted for everything from digestion to fertility. But not all probiotics are the same. The benefits depend on the exact strain, dose, and the condition being targeted. If you’re considering a probiotic, here’s what the research actually says about choosing the right one.

Why strain matters

Probiotics are identified by genus, species, and strain. For example, Lactobacillus rhamnosus GG is very different from Lactobacillus rhamnosus GR-1. While both are lactobacilli, only certain strains have proven benefits. Choosing a probiotic based on the right strain for your problem is key to getting results.

Probiotics for Constipation

Chronic constipation is common, especially in women. Research shows some probiotic strains may help by improving bowel regularity:

• Bifidobacterium lactis BB-12 – Has been shown in adults and children to soften stools and increase bowel movements.

• Lactobacillus casei Shirota – Found in Yakult®, this strain has some evidence for improving stool frequency in functional constipation.

It’s important to note that first-line intervention for constipation is to ensure adequate dietary fibre and fluid intake. Probiotics should always be combined with diet and lifestyle strategies for best effects.

Probiotics for Vaginal Health & Fertility

A healthy vaginal microbiome supports fertility by maintaining a protective acidic environment and reducing infections such as bacterial vaginosis (BV), which can affect conception. Strains with research in this area include:

• Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 – Together, these strains have been shown to restore healthy vaginal flora and reduce the risk of BV and yeast infections.

• Lactobacillus crispatus LBV88 - Less easily available but improves vaginal microbiome and fertility outcomes.

• Supporting vaginal health may indirectly support fertility, but more direct fertility studies are still emerging.

These strains are often found together in women’s health probiotic blends, but check the label for exact strain codes.

Probiotics for Irritable Bowel Syndrome (IBS)

IBS is a complex condition with varied symptoms (bloating, pain, diarrhoea, constipation). Probiotic effects are symptom-specific:

• Bifidobacterium infantis 35624 – Evidence supports its role in reducing abdominal pain, bloating, and bowel movement irregularities.

• Saccharomyces boulardii – A beneficial yeast that may help with diarrhoea-predominant IBS.

• Multi-strain formulations (including lactobacilli and bifidobacteria) are often more effective than single strains in IBS management.

What to look for on the label

When buying a probiotic, check for:

1. Specific strain name (not just the species) – e.g. Lactobacillus rhamnosus GG, not just “L. rhamnosus.”

2. Evidence-based dose – usually at least 1–10 billion CFU daily, depending on the strain.

3. Storage requirements – some need refrigeration; others are shelf-stable.

4. Australian listing (AUST L/AUST R) – ensures the product is regulated by the TGA.

Note: If you’re considering probiotics for gut health, fertility, or IBS, it’s always best to speak with a dietitian to ensure the strain and dose are right for you, and to combine them with a personalised nutrition plan. Probiotics are a supportive tool but they cannot cure or treat health conditions on their own. Individual responses vary, and their use should complement, not replace, personalised medical advice.

References

1. Hill C, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol. 2014;11:506–514.

2. Ouwehand AC, et al. Bifidobacterium infantis 35624 in the treatment of IBS: a randomized controlled trial. Am J Gastroenterol. 2009;104: 154–161.

3. Didari T, et al. Effectiveness of probiotics in irritable bowel syndrome: updated systematic review with meta-analysis. World J Gastroenterol. 2015;21(10):3072–3084.

4. McFarland LV. Evidence-based review of probiotics for IBS. World J Gastroenterol. 2010;16(17): 207–226.

5. Reid G, et al. Oral use of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 significantly alters vaginal flora: randomized, placebo-controlled trial. FEMS Immunol Med Microbiol. 2003;35(2):131–134.

6. Hemalatha R, et al. The role of vaginal probiotics in preventing bacterial vaginosis and improving reproductive outcomes. J Hum Reprod Sci. 2015;8(3):120–127.

7. Dimidi E, Christodoulides S, Scott SM, Whelan K. The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2017;105(3): 635–648.

8. Rao SS, et al. Effect of Lactobacillus casei Shirota on constipation in adults: a randomized, placebo-controlled study. Neurogastroenterol Motil. 2009;21: 53–60.