How probiotics and prebiotics support your gut

Our gut is much more than just a digestive organ – it houses a complex microbiome that has a significant impact on our health. Probiotics and prebiotics play a central role in this: while probiotics are live bacteria that promote the balance of the microbiome (gut flora), prebiotics serve as food for the gut flora and support the growth of beneficial microorganisms. But what exactly is behind them, what benefits do they offer, and how can they be used effectively? This article provides everything you need to know about these small helpers with big impact.

Table of Contents

• What is the microbiome?
• What are probiotics and prebiotics?
• What are the health benefits of pro-/prebiotics?
• Should I take probiotics, prebiotics, or both?
• Where are pro-/prebiotics found?
• Can pro-/prebiotics have side effects?
• Pro-/prebiotics and antibiotics
• Summary

What is the microbiome?

The gut flora, now referred to as the microbiome, consists of trillions of bacteria, viruses, and fungi in the intestines. The gut flora has the following functions, among others:

• Digestion – Breaks down complex carbohydrates and fibers, produces short-chain fatty acids, and synthesizes vitamins (B1, B9, B12, K).
• Fat metabolism – Supports fat digestion through the breakdown and recycling of bile acids.
• Immune system – Strengthens the immune defenses, prevents the spread of harmful bacteria, and regulates inflammation.
• Nervous system – Influences the brain via the gut-brain axis and produces neurotransmitters such as serotonin.
• Hormonal regulation – Controls metabolic processes like blood sugar, hunger, and fat storage through hormones.

Source: Cleveland Clinic, 2023

What are probiotics and prebiotics?

Probiotics are foods or dietary supplements that contain live microorganisms (e.g., lactic acid bacteria such as lactobacilli and bifidobacteria). They support the gut flora by promoting the growth of healthy bacteria and displacing harmful germs. They are found in fermented foods such as yogurt, sauerkraut, and kefir.

Prebiotics are indigestible fibers that serve as a food source for beneficial gut bacteria. They support their reproduction and activity, thereby improving gut health. Important prebiotics include inulin and oligofructose, which are found in foods like onions, garlic, bananas, and chicory.

Source: Mayo Clinic, 2022 

What are the health benefits of pro-/prebiotics?

Probiotics are live microorganisms that help maintain the balance of the gut flora, while prebiotics serve as nourishment for these beneficial bacteria. Below is a list of health benefits of probiotics:

• Microbial balance: Probiotics help maintain microbial balance in the body by combating harmful bacteria, fungi, and viruses, and supporting beneficial microorganisms.
• Protection against infections: Probiotics can help prevent or alleviate infections such as urinary tract infections, antibiotic-associated diarrhea, gum disease, and skin issues like acne.
• Support for digestion: Probiotics aid digestion by improving the absorption of key nutrients and medications, increasing bacterial diversity in the gut, and relieving symptoms such as bloating or constipation.
• Immune system support: They train the immune system to better recognize and combat harmful microbes, which can reduce the risk of chronic infections and inflammation.
• Other possible effects: There is evidence that probiotics can influence the nervous system, metabolism, and mood. They may affect pain tolerance, blood sugar regulation, and inflammatory processes.

Source: Cleveland Clinic, 2023 

Should I take probiotics, prebiotics, or both?

The combination of probiotics (beneficial bacteria) and prebiotics (their food source) is often most effective for gut health. However, in most cases, a healthy, balanced diet with fiber-rich foods such as vegetables, fruits, and whole grains is sufficient to support the microbiome. The additional intake of pro- and prebiotics can be helpful in the case of specific complaints or after a course of antibiotics, and should be tailored to individual needs (Mayo Clinic 2022).

Where are probiotics and prebiotics found?

1. Foods

Probiotic foods (contain live bacteria)

• Yogurt (Lactobacillus acidophilus, Bifidobacterium bifidum, Streptococcus thermophilus)

• Kefir (Lactobacillus kefiri, Lactobacillus casei, Saccharomyces kefir (yeast), Bifidobacteria)

• Sauerkraut (unpasteurized) (Lactobacillus plantarum, Lactobacillus brevis)

• Kimchi (Lactobacillus kimchii, Lactobacillus plantarum)

• Miso (Lactobacillus fermentum, Aspergillus oryzae (mold))

• Tempeh (Rhizopus oligosporus (fungus), Bifidobacteria)

• Kombucha (Acetobacter xylinum, Gluconacetobacter, Saccharomyces cerevisiae (yeast))
  

Prebiotic foods (fiber for gut bacteria)

• Apples, bananas

• Barley

• Chicory root

• Green dandelion

• Garlic, onions

• Oats

• Soybeans

• Wheat

Source: Nebraska Medicine, 2022

2. Dietary supplements

Many dietary supplements contain probiotics (live microorganisms such as Lactobacillus, Bifidobacterium) and prebiotics (fibers like inulin) that support the growth of beneficial gut bacteria. They are often used to support gut health and the immune system.

Tips for choosing a suitable probiotic/prebiotic

When choosing a probiotic or prebiotic product, look for well-studied bacterial strains such as Lactobacillus or Bifidobacterium. Proven strains are those that have been scientifically researched and often carry a specific strain designation (e.g., Lactobacillus plantarum 299v). In the scientific literature, doses ranging from 10⁸ to 10¹⁰ colony-forming units (CFUs) — and sometimes up to 10¹¹ CFUs — are described as effective. The optimal dosage depends on the purpose of use, duration of intake, the bacterial cultures included, and the form of administration.

Prebiotic fibers such as:

• Inulin

• Fructooligosaccharides (FOS)

• Galactooligosaccharides (GOS)

• Xylooligosaccharides (XOS)

• Lactitol

• Lactosucrose

• Lactulose

• Soy oligosaccharides

• Trans-galactooligosaccharides (TOS)

support the growth of healthy gut bacteria. Probiotics are available in powder and capsule form. Choose the product based on your needs — for example, for gut health or immune support — and pay attention to quality seals and scientific studies supporting effectiveness.

Sources: Markowiak, P., et al, 201; Nutrimmun, n.d. 

Can probiotics and prebiotics have side effects?

For healthy individuals, the consumption of prebiotics and probiotics is generally safe and rarely causes health issues. However, some people may temporarily experience bloating and digestive discomfort when they consume more probiotics. Individuals with weakened immune systems, severe illnesses, or premature infants may be at a slightly increased risk of infection from harmful microbes that may be present in inadequately tested products. The use of probiotics/prebiotics should always be discussed with a trusted physician (Cleveland Clinic, 2023; Eufic, 2023).

Probiotics, prebiotics, and antibiotics

Probiotics, prebiotics, and antibiotics have different but interconnected functions:

• Probiotics and prebiotics are important supporters of the gut flora.

• Antibiotics combat bacterial infections but can also destroy beneficial gut bacteria, potentially leading to dysbiosis (imbalance of gut flora).

Taking probiotics and prebiotics can be helpful both during and after antibiotic therapy. Studies show that probiotics taken during antibiotic use can reduce antibiotic-associated diarrhea. It’s important to take them at a different time (at least two hours after the antibiotic) to avoid destruction of the probiotic bacteria. After completing a course of antibiotics, probiotics and prebiotics can help restore the gut flora and prevent long-term imbalances. Prebiotic fibers also support the growth of the remaining beneficial bacteria.
(Rodgers, B.,et al., 2013; Innerhealth, 2023).

Summary

Probiotics are live microorganisms that support the balance of the gut flora, while prebiotics are indigestible fibers that serve as food for these beneficial bacteria. Both contribute to digestion, immune system support, and overall health. Probiotics are found in fermented foods such as yogurt, sauerkraut, and kefir, while prebiotics are present in fiber-rich foods like onions, bananas, and whole grains. Combining both can be particularly beneficial, especially after antibiotic therapy. While generally safe for most people, individuals with weakened immune systems should consult a doctor before using them.