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Probiotics: How Many Billion CFU do I Need to Maintain Daily Digestive Health?

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  • The right dose of probiotics will depend on an individual’s purpose for taking probiotics
  • A daily dose of 10-15 billion CFU is advisable for individuals seeking everyday immune and digestive support

What dose should I take?

A push towards using natural methods to maintain digestive health in recent years has led to an increased interest in probiotics—live microorganisms which, when taken in adequate amounts, confer benefits for immune and digestive health.1 Upon learning of probiotic benefits, people often want to know what constitutes as an “adequate” amount? However, because there are so many different probiotic organisms and variables to consider when making recommendations, a set dosage has not been established.2 Consequently the answer to “what dose should I take?” will depend on an individual’s purpose for taking probiotics.

Colony forming units

Probiotic potency is expressed in CFU, or colony forming units. This is a unit of measure used in microbiology to estimate the number of bacteria in a sample capable of dividing and forming colonies. Although the vast majority of positive clinical trials indicate that probiotic doses of 10-20 billion CFU per day are sufficient for maintaining immune and digestive health, products featuring CFUs of 50-100 billion are becoming increasingly common.3,4 While it may be tempting to assume that a larger CFU translates to greater potency and thus greater probiotic benefits, this is not necessarily the case.5

A regular dose of high-quality bacteria

In essence, the goal of probiotics is to balance the intestinal ecosystem. Because most people do not need an enormous CFU to achieve this, high-dose probiotic regimens (>50 billion CFU) have typically been reserved for clinical use with medical conditions characterized by extreme gastrointestinal dysfunction or dysbiosis.6,7 To date, there is little evidence to suggest that ingesting more probiotic bacteria than needed will result in greater benefits.8 Rather than overwhelming the gut with a “mega-dose” of bacteria, providing a regular infusion of high-quality bacteria represents a more biologically meaningful approach to health maintenance. 

All things considered, a daily dose of 10-15 billion CFU is advisable for individuals seeking everyday immune and digestive support. 

This not to say that doses larger than 15 billion CFU are not appropriate for some individuals. Research suggests that high doses of probiotics may be beneficial for people who have experienced a significant alteration to their gut microbiome due to illness, intense antibiotic therapy, or exposure to environmental toxins.9 Individuals in need of significant digestive support should speak with a medical professional about their health status and whether a high-dose probiotic regimen can help. 

Survivability and stability

It is also worth mentioning that CFU is not the only variable in the probiotic dosage equation. The survivability of a probiotic product’s strains and the methods used to provide stability and enhance survival within the digestive system are just as important as the number of viable bacteria it provides.5,10 For a deeper dive check out “Probiotics 101: Everything you need to know”.

Gina Jaeger, PhD is a Developmental Specialist and Lead Research Writer for Nordic Naturals. She holds a doctorate in Human Development, and has published several research articles on children's cognitive development. Gina enjoys studying and educating others on strategies for optimizing health and wellness throughout the lifespan.

1. Hill C et al. Nat Rev Gastroenterol Hepatol. 2014. 11(8): p. 506-14.
2. Farnworth ER. J Nutr. 2008: 138: (suppl):1250S-4S.
3. Williams N. Am J Health Syst Pharm. 67(6): p. 449-458
4. Kliger B, Cohrssen A. Am Fam Physician. 2008. 78(9): p. 1073-1078
5. Senok AC, et al. Clinical Microbiology and Infection. 2005. 11(12): p. 958-956.
6. Mimura T, et al. Gut. 2004. 53: p.108-114.
7. Bibiloni R, et al. Am J Gastroenterol. 2005. 100(7): p.1539-1546.
8. Gill HS, et al. Am J Clin Nutr, 2001. 74(6): p. 833–839.
9. Ouwehand, AC. Beneficial Microbes. 2017. 8(2): p. 143-151.
10. Fenster K, et al. Microorganisms. 2019. 7(3):83.