Probiotics vs Prebiotics: what to choose and for whom

Probiotic or prebiotic is a question best decided from the specific situation, not from advertising. The editorial team examined in which cases living bacteria are more appropriate, when it is better to "feed" one's own microbiota, what an athlete should choose, and how to avoid typical mistakes when buying.

The principle of choice: the task, not the fashion

The popularity of gut supplements is growing, but the choice between a probiotic and a prebiotic is often made at random: what friends advised or what is on sale. The editorial team proposes a different approach - start with the specific task. Probiotics make sense when there is a clear situation for which a particular strain has been studied. Prebiotics - when you need to support your own microbiota over the long term through nutrition.

The first thing to do is assess your diet. If you rarely eat vegetables, legumes, whole grains or fruit, then the cheapest and most effective step is to increase the amount of fiber in your food. No supplement compensates for a diet poor in plant foods.

The second is to determine whether there is a temporary risk factor: a course of antibiotics, travel to a country with a different microflora, a period of intense training and competition. It is precisely in such situations that probiotics have the most evidence.

The third is to honestly assess symptoms. Constant abdominal pain, blood in the stool, sharp weight loss, nighttime diarrheal episodes - this is a reason to see a doctor, not to buy supplements. Self-treatment with probiotics may delay the diagnosis of serious diseases.

When it is more logical to choose a probiotic

The most substantiated scenario is the prevention of diarrhea during a course of antibiotics. The Cochrane review by Goldenberg and colleagues (2017) confirmed a reduction in the risk of diarrhea associated withClostridioides difficile. Most often such studies used certain strains of lactobacilli and the yeastSaccharomyces boulardii.

At the same time it is worth remembering the study by Suez and colleagues (2018): in their work, taking probiotics after antibiotics slowed the return of one's own microbiota to its baseline state. So the idea of "taking probiotics for months to restore the flora" is not as clear-cut as advertising presents it.

Another scenario is the prevention of respiratory infections. The Cochrane review by Hao, Dong and Wu (2015) concluded that probiotics may somewhat reduce the frequency of acute upper respiratory tract infections, although the quality of the evidence was rated as low. So expectations should be moderate.

When choosing a probiotic, pay attention to the following details:

• the label states the genus, species and strain, not just a "complex of lactobacilli";
• the number of colony-forming units (CFU) is guaranteed to the end of the shelf life, not at the time of manufacture;
• for the specific strain there is research relevant to your task;
• storage conditions (refrigerator or room temperature) are maintained all the way to the buyer.

When it is more logical to choose a prebiotic

Prebiotics are appropriate for those who want to support gut health over the long term, especially if the diet lacks plant fiber. The ISAPP consensus (Gibson et al., 2017) emphasizes that a prebiotic must be selectively utilized by microbes and confer a health benefit, so it is worth choosing well-studied substances: inulin, FOS, GOS.

The advantage of prebiotics is stability and convenience. They can be added to yogurt, coffee, porridge or a protein shake; they are not afraid of room temperature and do not lose activity over time, as living bacteria do. They are also usually cheaper than quality probiotics.

The main problem is tolerability. Prebiotics ferment with the production of gases, so at the start of intake bloating and discomfort are possible. A practical rule for dietary supplements is to start with a small serving, about 2-3 g per day, and gradually increase to the amount recommended by the manufacturer over several weeks, drinking enough water.

For people with irritable bowel syndrome, prebiotics can worsen symptoms, because many of them belong to the FODMAP group. If your condition worsens after starting, it is better to stop and discuss the situation with a gastroenterologist or dietitian.

The choice for athletes

The ISSN position statement (Jäger et al., 2019) is one of the most comprehensive sources on probiotics in sport. According to its conclusions, certain strains may reduce the frequency or duration of upper respiratory tract infections and ease gastrointestinal symptoms in athletes. These effects are especially valuable during periods of intense training, travel and competition.

In practice this means: if an athlete often gets sick during the competition season or has stomach problems during trips, it is reasonable to try a probiotic with a strain that was studied in precisely such conditions. Intake should be started in advance, not on the day of departure, because in studies the effect was assessed after weeks of regular intake.

Prebiotics for athletes are primarily part of the daily diet outside the competition period. Before starts and on days of prolonged exercise the amount of fiber is often deliberately reduced to lower the risk of stomach discomfort. So starting a new prebiotic in a competition week is a bad idea.

Synbiotics, safety and typical mistakes

Synbiotics combine a probiotic and a prebiotic. According to the ISAPP consensus (Swanson et al., 2020), this can be either a simple mixture of components with separately proven action, or a "synergistic" combination in which the prebiotic is selected specifically for a particular strain. In practice most commercial products belong to the first type.

For healthy people probiotics are usually safe. However, for people with immunodeficiency, in critical condition, with central venous catheters or after major surgery, there is a risk of infections caused by the probiotic microorganisms themselves. For such patients intake is possible only by a doctor's decision.

The typical mistakes buyers make are:

1. Choosing by the highest number of CFU instead of a studied strain.
2. Expecting a probiotic to "cure" any digestive problems.
3. Taking prebiotics in a large serving right away without gradual adaptation.
4. Replacing vegetables and whole foods with supplements.
5. Violating the storage conditions of living cultures.

The effect of supplements should be assessed after several weeks of regular intake. If there are no changes, this is a normal result, not a reason to endlessly change products. Perhaps the specific task simply cannot be solved with supplements.

Editorial conclusions

Probiotics are a choice for specific short-term tasks: antibiotics, travel, periods of high load in athletes. They should be chosen by strain and evidence, not by the number of bacteria on the package.

Prebiotics are a tool for long-term support of one's own microbiota, but the best prebiotic remains a varied diet with vegetables, fruit, legumes and whole grains. Supplements are useful when the diet does not allow you to get enough fiber.

People with chronic bowel diseases, immunodeficiency or alarming symptoms should first see a doctor.

For more on the mechanisms, read the article "Probiotics or Prebiotics: what is the difference." We also recommend our articles on an athlete's nutrition on the road and on fiber in an athlete's diet.

References

1. Hill C, Guarner F, Reid G, 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(8):506–514.
2. Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017;14(8):491–502.
3. Goldenberg JZ, Yap C, Lytvyn L, et al. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev. 2017;12:CD006095.
4. Hao Q, Dong BR, Wu T. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2015;(2):CD006895.
5. Jäger R, Mohr AE, Carpenter KC, et al. International Society of Sports Nutrition Position Stand: Probiotics. J Int Soc Sports Nutr. 2019;16(1):62.
6. Suez J, Zmora N, Zilberman-Schapira G, et al. Post-antibiotic gut mucosal microbiome reconstitution is impaired by probiotics and improved by autologous FMT. Cell. 2018;174(6):1406–1423.
7. Swanson KS, Gibson GR, Hutkins R, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nat Rev Gastroenterol Hepatol. 2020;17(11):687–701.