Probiotics Learning Lab Impartially created by the experts at OptiBac

The Numbers Myth:

The numbers probiotic myth image

"The more
strains, the

Research says:

It depends on the condition. The most researched probiotic for diarrhoea is Saccharomyces boulardii - this is a single strain.

Due to the diverse nature of the gut microflora it can be instinctive to assume that a probiotic containing many different strains is best. However, the research simply does not support this theory. There are clinical trials that test single strains, or two-strain formulas, and which demonstrate excellent health benefits. For instance S. boulardii is the most researched probiotic for diarrhoea in adults1, and it is a single strain. B. lactis BB-12® is the most documented of all the Bifidobacteria strains, and clinical trials show it is particularly helpful for symptoms of constipation2. Again, this is only a single strain!

The combination of L. rhamnosus Rosell-11 and L. acidophilus Rosell-52 has been shown in multiple clinical trials ro reduce diarrhoea associated with antiobiotics3, and this is a two-strain formula. Similarly L. reuteri RC-14® and L. rhamnosus GR-1®, another two strain formula, has been shown clinically to have a significant part to play in the management of thrush4, cystisis5 and bacterial vaginosis6.

One of the best ways in which probiotic supplements can work in synergy with our body is by creating a favourable environment for the indigenous bacteria to flourish7. So although a probiotic supplement might not contain many different bacteria, if it is performing well it will naturally enhance the diversity of bacteria in the body.

In addition, because microorganisms are so delicate it’s quite a challenge to ensure they are compatible alongside each other in a supplement – if a formula contains many strains, survival becomes an even bigger challenge8.

The numbers-all probiotic myth image

Above: A microscopic image of the Saccharomyces boulardii strain - the most researched probiotic for diarrhoea.

Look out for:

The most researched probiotic for the health condition – even if it contains fewer strains.

Further Reading

Health professionals can read more on B. lactis BB-12® and What is Saccharomyces boulardii?

This myth has been busted by Megan Crowch, BSc (Hons) Physiology, Herbal Medicine Diploma (IRH practicing member).

  1. McFarland (2010) Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World J Gastroenterol; 16, 18: 2202-22
  2. Eskesen et al. (2015) Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial. Br J Nutr; 114, 10: 1638-46.
  3. Foster et al. (2011) A comprehensive post-market review of studies on a probiotic product containing Lactobacillus helveticus R0052 and Lactobacillus rhamnosus R0011. Benef Microbes; 2, 4: 319-34.
  4. Martinez et al. (2009) Improved treatment of vulvovaginal candidiasis with fluconazole plus probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14. Lett Appl Microbiol; 48, 3: 269-74.
  5. Beerepoot et al. (2012) Lactobacilli vs antibiotics to prevent urinary tract infections: a randomized, double-blind, noninferiority trial in postmenopausal women. Arch Intern Med; 172, 9: 704-12.
  6. Anukam et al. (2006) Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: randomized, doubleblind, placebo controlled trial. Microbes Infect; 8, 6: 1450-4
  7. Studies have demonstrated that even when taking specific strains in a probiotic supplement the general levels of Bifidobacteria & Lactobacilli in the gut can increase e.g. Laake et al. (1999) Influence of fermented milk on clinical state, fecal bacterial counts and biochemical characteristics in patients with ileal- pouch- anal-anastomosis. Microbial Ecology in Health and Disease, 11: 211-217.
  8. Training event from Chr. Hansen representative on latest research development (2014) Andover, UK.

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