Probiotics: Their Impact on Health and Key Considerations
Unlike other dietary supplements, the effects of probiotics on our health are well-supported by numerous studies. However, this does not mean that they are always beneficial in every case—there are some important factors to consider. First, selecting the right strain is crucial. Probiotics belong to the bacterial group of the microbiome, and just as bacteria have existed abundantly around us since ancient times, probiotics also come in a vast variety. Many researchers have been studying the effects of different probiotic strains for a long time, and a considerable amount of reliable information has been compiled. Additionally, new probiotic strains are continuously being developed, and experiments are ongoing to verify their effectiveness.
Probiotics exist in many different forms, and specific strains offer distinct benefits. Some example strains are listed below:
1. Lactobacillus rhamnosus GG (LGG)
Improves gut health, prevents diarrhea (especially antibiotic-associated diarrhea)
Szajewska et al., 2013 (Cochrane Database Syst Rev.)
2. Bifidobacterium longum
Enhances immunity, reduces inflammation, supports gut microbiota
O’Callaghan & van Sinderen, 2016 (Front Microbiol.)
3. Lactobacillus reuteri
Supports stomach health, inhibits H. pylori, has antimicrobial properties
Francavilla et al., 2014 (Clin Gastroenterol Hepatol.)
4. Lactobacillus helveticus
Helps regulate blood pressure by producing peptides that inhibit ACE
These effects have been reported based on clinical trials. However, individual responses vary, and not everyone will experience the same benefits. In particular, if the gut environment is severely compromised, taking probiotics may not yield the desired effects.
As mentioned in a previous post, probiotics consumed orally must survive harsh stomach acid and bile to reach the intestines in sufficient numbers. Therefore, probiotic supplements need to contain an adequate number of live bacteria. The amount is typically expressed in CFU (Colony Forming Units), and it is generally recommended to consume daily at least 1 to 10 billion CFU for effectiveness. Many probiotic manufacturers are developing coated capsules and other delivery methods to ensure that probiotics reach the intestines intact. Some strains are also engineered to withstand stomach acid. Additionally, a significant number of probiotics die during packaging, distribution, and storage.
A common reason why probiotics fail to provide benefits is insufficient strains or the use of unverified strains. Another reason is improper storage, leading to bacterial death. Probiotics are living microorganisms, and the first step in effectively delivering them to the gut is consuming them in a viable state. Unlike harmful bacteria, probiotics are highly sensitive to their environment. Most probiotic supplements are freeze-dried to maintain dormancy, allowing for extended storage. However, once environmental conditions change and they awaken, they may become vulnerable and die.
How to Properly Store Probiotics
Temperature: Probiotics are sensitive to temperature. They can die if exposed to high temperatures (above 40°C / 104°F) or extremely low temperatures (below -20°C / -4°F). Many probiotic products require refrigeration to keep them in a dormant state. If probiotics are exposed to room temperature, they may wake up and attempt to grow and multiply, but due to a lack of nutrients, they may starve to death. It is recommended to store probiotics at around 4°C (39°F) in the refrigerator whenever possible.
Humidity: Freeze-dried probiotics may wake up when exposed to moisture. If they awaken and lack nutrients, they may die, or they may perish if they are re-dried. Therefore, always seal the packaging properly to prevent moisture exposure.
Oxygen Exposure: Some probiotics are sensitive to oxygen. If exposed to air, oxidative stress can damage and kill them. It is advisable to store probiotics in an airtight container.
Light: Certain probiotics may lose viability when exposed to sunlight or UV light for extended periods. To prevent this, store them in a dark place or use opaque containers.
Can Probiotics Be Harmful?
While probiotics are beneficial microorganisms, they can be harmful in specific situations:
Immunocompromised Individuals: Cancer patients undergoing chemotherapy, organ transplant recipients, HIV patients, and newborns with underdeveloped immune systems may be at risk of sepsis or bacteremia if probiotics cross the intestinal barrier and enter the bloodstream.
Small Intestinal Bacterial Overgrowth (SIBO): Some individuals may experience excessive bacterial growth in the small intestine due to excessive probiotic intake, leading to bloating, gas, or digestive discomfort.
Key Takeaways
Choosing the right strain is essential.
Probiotics should be consumed in adequate amounts over a consistent period.
Individual responses may vary—there is no universal formula for which strain, how much, or how long probiotics should be taken to see effects.
Those with weakened immune systems or digestive issues should consult a doctor before taking probiotics.
By selecting the right probiotic strains, consuming them in proper amounts, and storing them correctly, you can maximize their potential benefits.
References
Case Adams (2014), Probiotics Simplified How Nature’s Tiny Warriors Keep Us Healthy, Logical Books
Szajewska, H., et al. (2013). Probiotics for the prevention of antibiotic-associated diarrhea in children. Cochrane Database Syst Rev.
O’Callaghan, A., & van Sinderen, D. (2016). Bifidobacteria and their role as members of the human gut microbiota. Front Microbiol.
Francavilla, R., et al. (2014). Lactobacillus reuteri in the treatment of Helicobacter pylori infection in children. Clin Gastroenterol Hepatol.
Jäkälä, P., & Vapaatalo, H. (2010). Antihypertensive peptides from milk proteins. Curr Pharm Des.
Madhu, A. N., et al. (2022). Probiotic Lactobacillus casei in gut health and disease. Probiotics Antimicrob Proteins.
Yan, F., et al. (2017). Probiotics for inflammatory bowel disease. Microbiol Res.
An, H. M., et al. (2021). Lactobacillus acidophilus: a potential probiotic for human health. J Appl Microbiol.
Shah, N. P. (2007). Functional cultures and health benefits. Int Dairy J.
Isolauri, E., et al. (2000). Probiotics: effects on immunity. J Allergy Clin Immunol.
Wegmann, U., et al. (2007). The role of lactococci in the gut. Microbiol Mol Biol Rev.
Leo & Leah 
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