What’s the deal with probiotics?
Some people say there’s no evidence that they work, while other people swear by them for their digestive health and beyond. So, what IS the deal with probiotics? Read on to find out!
Is there research proving they work?
For many conditions and disease processes, the answer is YES! But, for some other conditions, in addition to evidence that shows they work, there is also research that shows there’s no real effect. What makes it even trickier is that not all preparations of probiotics are equally potent, and some studies don’t specify the source, the strain, or the potency of the preparations they are testing. And many studies are too small for us to be able to draw definitive conclusions. Far from ideal, right? So, for some conditions, the jury – in terms of evidence – is still out. But there are many studies that do show efficacy for certain conditions. And there are also many anecdotal, lived experiences of probiotics’ being a game-changer for people suffering from all kinds of conditions. To be clear, anecdotal experiences are never (ever!) considered evidence of efficacy in the medical world, but they can be a source of information for the decisions we make for our own bodies.
Some basics, to start:
Beyond testing and quality, there are many different strains -- or different types of good bacteria and yeasts -- in probiotics. And their actions are strain specific, meaning that different types of good bacteria and yeasts have been observed to be effective for different conditions. For example, Lactobacillus rhamnosus CRL 1505, has been studied for the prevention of airway infections. In contrast, L. rhamnosus GG has been studied for gastrointestinal issues, like rotavirus (GI) infections and colic. (1) So, even though they sound nearly identical, their effects and uses are different.
Also how and when you take probiotics is important. Although there isn’t hard evidence for this (yet, anyway), most practitioners recommend taking them on an empty stomach, so they are not as exposed to gastric acid, which could make them more inactive. In fact, there are also newer preparations of probiotics that are encapsulated to protect them from the gastric acid in the stomach and, theoretically, allow them to have an even greater effect in the intestine. There are even probiotics that have “nanoarmor” that aims to protect beneficial bacteria from the action of antibiotics. (2)
Most probiotics have to be refrigerated, but there are shelf-stable ones as well that do not need refrigeration. These are great for taking on trips – to help with traveler’s diarrhea, for example.
The dose is also important. A typical dose of probiotics is 10-20 billion CFUs (colony forming units) a day for older children and adults and 1-10 billion CFUs a day for infants.
Here’s a quick review of some of the research:
Colic:
Most meta-analyses (studies that look at a lot of studies) found no clear evidence that probiotics are more effective than placebo at preventing infantile colic. However, daily crying time appeared to be reduced with probiotic use compared to placebo! (2) Which any parent can tell you is definitely a gamechanger. Other studies have shown that L. reuteri DSM 17938 and L. rhamnosus GG were effective to manage infant colic. (1) The most commonly studied probiotic to date is Lactobacillus reuteri. (1,3)
Diarrhea and other intestinal diseases:
Various intestinal diseases such as AAD (antibiotic associated diarrhea), IBD, CD (Crohn’s disease), and CRC (colorectal cancer) are known to be closely associated with an imbalance between “good” (host-beneficial) bacteria and “bad” (host-harmful) bacteria. (4) Another, more medical way to describe this imbalance is “dysbiosis of the intestinal microbiota between host-beneficial and host-harmful intestinal bacteria.” And there is good evidence that probiotics can be useful for the treatment — and sometimes even the prevention — of these illnesses. (4)
One area where there has been a lot of research to support the use of probiotics is both infectious (meaning: contagious) and antibiotic associated diarrhea. Certain probiotics have been shown in some (but not all!) studies to help both acute diarrhea and antibiotic-associated diarrhea. L. rhamnosus GG and Saccharomyces boulardii may shorten both the duration of the illness and the severity of symptoms. (1)
But the microbiome has an impact on our overall system, so what about the use of probiotics in other conditions? That’s where it gets a bit trickier, as the evidence for the use of probiotics to treat other conditions is sometimes not as definitive as the ones for their use in conditions that primarily involve the digestive system. Below are some conditions , though, that do have some evidence to support their use.
Eczema:
Lactobacillus rhamnosus HN001 (HN001) taken by mothers from 35 weeks of gestation until 6 months post-partum if breastfeeding and their child from birth to age 2 years reduced the risk of eczema by half during the first 2 years of life. (4) It appears that it is vital that the child also receive the supplement themselves, though, as this reduction in eczema risk is not seen when only Mom (not baby) takes probiotics. (5)
Mental health:
The gut microbiome (the overall ecosystem of all the microorganisms, including good and bad bacteria, in your gut) is instrumental in the production of neurotransmitters that affect our mental health, like serotonin, dopamine, GABA, and glutamate, which are deeply important to our mood regulation. In fact, about 95% of the body’s serotonin is made in the gut. (6)
So it makes perfect sense that probiotics could affect our mental health in a positive way. A study on people who received Lactobacillus rhamnosus HN001 during pregnancy and postpartum had significantly lower depression and anxiety scores in the postpartum period. (7)
Post C section (for baby!):
A small study that looked at probiotic, prebiotic, and synbiotic interventions in newborns delivered by C-section showed that these interventions led to beneficial gut microbiota in these newborns that were closer to that in vaginally delivered newborns. This was especially true regarding Bifidobacterium colonization. Lactobacillus, Bifidobacterium, Propionibacterium, and Streptococcus, or a combination of those. The dosages varied between 2 × 10^6 (2x 1 million) and 9 × 10^11 (9 x 100 billion) CFU (colony forming units) per day and were consumed during pregnancy and/or lactation. Probiotic strains were combined with galacto-oligosaccharides, fructo-oligosaccharides, or bovine milk-derived oligosaccharides in the synbiotic formulas. (8)
Mastitis:
In a review of six different studies, Lactobacillus fermentum CECT 5716, Lactobacillus salivarius CECT5713, and Lactobacillus gasseri CECT5714 were shown to be effective in reducing the incidence of mastitis and improving the symptoms of breastfeeding mastitis. (9) But, they did not have enough long term follow up to determine long term efficacy and adverse reactions. Another study showed that Lactobacillus fermentum CECT5716 MAY reduce the risk of mastitis. (9) The fact that this second study couldn’t draw strong conclusions was due to the low reliability of the current evidence, so it was not possible to conclude that probiotics could definitely reduce the risk of breast pain and breast injury. (10)
The conditions reviewed above have some good evidence that probiotics treat them effectively, but there are other processes, like recurrent UTIs, recurrent yeast infections, and recurrent abdominal pain where the evidence is not as clear.
But the good news is that — unless you are a premature infant, severely immunocompromised, or have things like central intravenous lines — the risk of trying probiotics is low. So, this is an area where making an independent decision to try something is pretty much fine, even from an evidence based medical standpoint. Since, in many cases, when there has been mixed research, we have not been able to determine that it definitely works — but also they have not been able to determine that it definitely does NOT work.
The main risk is cost. Which, in some cases, can be quite significant. So, if you don’t notice a difference after two to three months on probiotics, most people would recommend stopping.
Including fermented foods in your diet, however, is a delicious and — especially if you make it at home — cost effective way to get multiple strains of beneficial bacteria into your microbiome. Dietary sources of good bacteria are almost always a great idea; just be careful of the high salt content in many fermented vegetables. Making things like sauerkraut is easy, fun and extremely affordable, so give it a try.
Hopefully, this gives you a sense of the promise, but also some of the complexity, of figuring out if and how probiotics can be a part of your life. Ultimately, the choice is yours, and I wish you so much luck and fun in exploring how to incorporate these amazing little “good” bacteria into your everyday life!
Photo by Geraud Pfeiffer
REFERENCES
(1) Boggio Marzet C, Burgos F, Del Compare M, Gerold I, Tabacco O, Vinderola G. Approach to probiotics in pediatrics: the role of Lactobacillus rhamnosus GG. Arch Argent Pediatr. 2022 Feb;120(1):e1-e7. English, Spanish. doi: 10.5546/aap.2022.eng.e1. Epub 2021 Dec 14. PMID: 35068121.
(2) Pan J, Gong G, Wang Q, Shang J, He Y, Catania C, Birnbaum D, Li Y, Jia Z, Zhang Y, Joshi NS, Guo J. A single-cell nanocoating of probiotics for enhanced amelioration of antibiotic-associated diarrhea. Nat Commun. 2022 Apr 19;13(1):2117. doi: 10.1038/s41467-022-29672-z. PMID: 35440537; PMCID: PMC9019008.
(3) Ong TG, Gordon M, Banks SS, Thomas MR, Akobeng AK. Probiotics to prevent infantile colic. Cochrane Database Syst Rev. 2019 Mar 13;3(3):CD012473. doi: 10.1002/14651858.CD012473.pub2. PMID: 30865287; PMCID: PMC6415699.
(4) Kim SK, Guevarra RB, Kim YT, Kwon J, Kim H, Cho JH, Kim HB, Lee JH. Role of Probiotics in Human Gut Microbiome-Associated Diseases. J Microbiol Biotechnol. 2019 Sep 28;29(9):1335-1340. doi: 10.4014/jmb.1906.06064. PMID: 31434172.
(5) Wickens K, Barthow C, Mitchell EA, Stanley TV, Purdie G, Rowden J, Kang J, Hood F, van den Elsen L, Forbes-Blom E, Franklin I, Barnes P, Fitzharris P, Maude RM, Stone P, Abels P, Murphy R, Crane J. Maternal supplementation alone with Lactobacillus rhamnosus HN001 during pregnancy and breastfeeding does not reduce infant eczema. Pediatr Allergy Immunol. 2018 May;29(3):296-302. doi: 10.1111/pai.12874. Epub 2018 Apr 6. PMID: 29415330.
(6) Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integr Med (Encinitas). 2018 Aug;17(4):28-32. PMID: 31043907; PMCID: PMC6469458.
(7) Slykerman RF, Hood F, Wickens K, Thompson JMD, Barthow C, Murphy R, Kang J, Rowden J, Stone P, Crane J, Stanley T, Abels P, Purdie G, Maude R, Mitchell EA; Probiotic in Pregnancy Study Group. Effect of Lactobacillus rhamnosus HN001 in Pregnancy on Postpartum Symptoms of Depression and Anxiety: A Randomised Double-blind Placebo-controlled Trial. EBioMedicine. 2017 Oct;24:159-165. doi: 10.1016/j.ebiom.2017.09.013. Epub 2017 Sep 14. PMID: 28943228; PMCID: PMC5652021.
(8) Martín-Peláez S, Cano-Ibáñez N, Pinto-Gallardo M, Amezcua-Prieto C. The Impact of Probiotics, Prebiotics, and Synbiotics during Pregnancy or Lactation on the Intestinal Microbiota of Children Born by Cesarean Section: A Systematic Review. Nutrients. 2022 Jan 14;14(2):341. doi: 10.3390/nu14020341. PMID: 35057522; PMCID: PMC8778982.
(9) Yu Q, Xu C, Wang M, Zhu J, Yu L, Yang Z, Liu S, Gao X. The preventive and therapeutic effects of probiotics on mastitis: A systematic review and meta-analysis. PLoS One. 2022 Sep 9;17(9):e0274467. doi: 10.1371/journal.pone.0274467. PMID: 36084006; PMCID: PMC9462749.
(10) Crepinsek MA, Taylor EA, Michener K, Stewart F. Interventions for preventing mastitis after childbirth. Cochrane Database Syst Rev. 2020 Sep 29;9(9):CD007239. doi: 10.1002/14651858.CD007239.pub4. PMID: 32987448; PMCID: PMC8094918.