Prebiotics are substances that may support a healthy gastrointestinal (GI) tract. The concept of prebiotics was introduced in 1995, and due to significant research findings, the interest in prebiotics has increased. Once thought to only affect the GI, we now know that prebiotics may indirectly influence various body systems. Because of these reasons, prebiotics are one of the most sought-after supplements; the global market value for prebiotic products was over six billion dollars in 2021, and continued growth in the market is expected.
This article will discuss prebiotics - what they are, where to find them, how to test for them, and why they are considered important for your gut health.
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What are Prebiotics?
Prebiotics are non-digestible substances that the microbes within our GI microbiome ferment and turn into energy sources called short-chain fatty acids (SCFA). SCFAs feed the microbiome, a group of collective organisms that resides within our large intestine (there are also small amounts in the stomach and small intestine). The microbiome impacts several bodily processes, including digestion and absorption, immune function, hormone synthesis, and more. Because they serve as an energy source, prebiotics can modify the function and makeup of the microbiome.
In addition to the effects on the microbiome, the SCFAs produced by prebiotics are small enough to enter into the bloodstream and may support beneficial effects on numerous body systems, which we will discuss later.
For a compound to be classified as a prebiotic, it must adhere to the following criteria:
- It should be resistant to stomach acid and enzymes and be unabsorbable in the gastrointestinal (GI) tract.
- It should be fermentable by the microbes in the microbiome.
- Microbes in the microbiome should grow and be stimulated by these compounds, and, as a result, the host's (human's) health may be positively impacted.
Prebiotics are found in the following foods:
- Bananas
- Garlic
- Chicory root
- Jerusalem artichokes
- Onions
- Breast milk
- Cow milk
- Sugar beet
- Beans
- Seaweed
- Wheat
- Honey
- Tomato
- Rye
- Soybean
Prebiotics are also often added to food products, including yogurt, cereals, infant formulas, bread, and desserts.
Prebiotics Vs. Probiotics
While prebiotics and probiotics sound similar, they are actually quite different. Probiotics are supplements that contain strains of beneficial microbes, while prebiotics are the food sources for those microbes. Prebiotics are typically found in high-fiber foods, while probiotics are found in fermented foods such as yogurts, kimchi, sauerkraut, pickles, and tempeh. Probiotics directly affect the cells within the gastrointestinal tract, while prebiotics primarily induce action by their byproducts, SCFAs. Prebiotics may have a beneficial effect on the type and number of probiotic microbes in the microbiome.
Potential Health Benefits of Prebiotics
Prebiotics produce SCFAs that enter the circulation and thus may influence various systems in the body. SCFAs may support the following body systems and contribute to the following benefits:
- Central Nervous System: they may support recall, memory, learning, and mood, and may contribute to slowing the dementia process and supporting brain health.
- Cardiovascular system: they may help maintain healthy cholesterol and triglyceride levels.
- Gastrointestinal system: they may support a healthy digestive system and contribute to maintaining a balanced gut environment.
- Musculoskeletal system: they may support calcium absorption in the bone.
- Immune System: they may support various immune markers.
- Integumentary system: they may support skin health by contributing to collagen and keratin formation and aiding in water retention in the skin.
Examples of Prebiotics Commonly Used
Prebiotics can be separated into five main groups: fructans, galacto-oligosaccharides, starch and glucose-derived oligosaccharides, other oligosaccharides, and non-carbohydrate oligosaccharides. The following are the most commonly used:
Fructans
Inulin and fructo-oligosaccharides (FOS) are two types of fructan prebiotics. Inulin consumption may support the growth of Bifidobacterium, which can help maintain a healthy GI barrier. A study with participants consuming vegetables rich in inulin for two weeks showed an increase in Bifidobacterium bacteria. Previous studies have shown Jerusalem artichokes, a vegetable high in inulin, to support the growth of Bifidobacterium bacteria as well.
Inulin also has antioxidant properties that may support GI health. Inulin may serve a protective role against lipopolysaccharide (LPS), a compound produced by certain bacteria.
FOS is added to many food products due to its potential to support regular bowel movements. Research suggests a dose of FOS ranging from 4-15g/day may help support digestive regularity. This effect may be due to the ability of FOS to stimulate the growth of beneficial bacteria in the microbiome and support mineral absorption. FOS has also been shown to help maintain healthy cholesterol levels.
Galacto-oligosaccharides (GAS)
Primarily found in dairy products and legumes, GAS can also support levels of Bifidobacterium. In addition, GAS may aid in the breakdown of fats and carbohydrates, support the growth and function of colonic cells, and contribute to a healthy GI tract.
Resistant Starch (RS)
RS belongs to the starch and glucose-derived oligosaccharides group of prebiotics. As its name implies, RS is resistant to metabolism in the upper GI tract. When they are metabolized in the large intestine, large amounts of butyrate, the primary fuel for colonic cells, are made. RS may aid in reducing inflammation in the GI tract, supporting a healthy weight, and maintaining balanced blood sugar levels.
There is current research investigating how to synthesize these compounds in labs, as companies know they could be profitable due to their potential health benefits.
Investigating GI Health
Comprehensive stool testing can be a valuable tool for investigating GI health. Results can help identify specific foods and supplements that may benefit overall health.
The comprehensive stool tests, GI 360, by Doctor's Data, and GI Effects, by Genova Diagnostics, evaluate many biomarkers related to gastrointestinal functioning. In terms of prebiotics, these tests give the total amount of SCFAs. They also break down the individual SCFAs, acetate, propionate, butyrate, and valerate and report their relative percentages. These tests also screen for many pathogenic and beneficial microbes, including bacteria, viruses, and yeasts. In addition, the pH level is given, which is essential to prevent the overgrowth of harmful microbes. Although different in certain ways, these tests can provide great insight into the complete function of the microbiome, including prebiotic status.
Summary
Prebiotics can be a helpful addition to your daily routine, whether through food or supplement. If you are still determining if you're getting enough prebiotics, functional medicine comprehensive GI testing can be helpful to assess markers related to prebiotics. Knowing that prebiotics may influence various body systems, prebiotics and their byproducts, SCFAs, are a valuable marker to track for many people.
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