What are Probiotics and Prebiotics?
Probiotics are live beneficial bacteria that are non-digestible. That is, they make it through your stomach and small intestine to colonize in your colon. Prebiotics are non-digestible food parts that make their way to your colon where they are preferentially fermented by healthy bacteria in the colon. You can take one or the other or both depending on your needs. Both promote the health and growth of healthy bacterial colonies in your colon.
Although all prebiotics are fiber, not all fiber is prebiotic. To be classified a prebiotic one must demonstrate that the ingredient resists stomach acidity, small bowel enzymes and absorption in the stomach and small bowel. It must be preferentially fermented by bacteria in the colon that promote health and wellbeing. The colon is optimal for this function given its slow transit time, nutrients and favorable pH.
Together with the gut immune system, colonic and mucosal microflora contributes significantly to the barrier that prevents pathogenic bacteria from invading the gastrointestinal (GI) tract. The intestinal flora promote energy through fermentation of carbohydrates that escape digestion in the upper gut.
Benefits of Prebiotics
Benefits of prebiotics include improvement in gut barrier function and host immunity, reduction of potentially pathogenic bacteria subpopulations (e.g., clostridia), and enhanced short chain fatty acid production. Ones of these short chain fatty acids is called is butyrate. Colonic epithelial cells preferentially use butyrate as an energy source. It is considered a key nutrient determining the metabolic activity and growth of colonocytes and may function as a primary protective factor against colonic disorders.
These short chain fatty acids also help regulate sodium and water absorption and can enhance absorption of calcium and other minerals. In addition, they act to lower colonic pH, which can inhibit growth of potential pathogens and promote the growth of beneficial bacteria such as bifidobacteria and lactobacilli.
Some may also play a role in improving immune function increasing T helper cells, macrophages, and neutrophils, and increased cytotoxic activity of natural killer cells. There is also some evidence of increased resistance to illness or infection with fiber intake.
The health outcome data for prebiotic intake is substantially more limited than for dietary fiber. However, it has been suggested that prebiotic intake may:
- Reduce the prevalence and duration of infectious and antibiotic-associated diarrhea,
- Reduce the inflammation and symptoms associated with inflammatory bowel disease,
- Exert protective effects to prevent colon cancer,
- Enhance the bioavailability and uptake of minerals, including calcium, magnesium, and possibly iron,
- Lower some risk factors for cardiovascular disease, and
- Promote satiety and weight loss and prevent obesity. (1)
What about Xylooligosaccharides?
Xylooligosaccharides are a form of prebiotic. The basic structure consists of sugar oligomers composed of xylose units, found naturally in fruits, vegetables, milk, honey and bamboo shoots. Unlike other forms of prebiotics, xylooligosaccharides are effective at lower doses. Why might this be important? Patients taking prebiotics often notice an increase in many of the same symptoms they are trying to resolve by optimizing their disordered microbiome; namely, bloating and abdominal pain. Naturally, these outcomes are a result of the commensal bacteria fermenting the prebiotic fibers and releasing gaseous byproducts. Most patients would not welcome a worsening of the very issues they’re trying to get rid of. The probiotics may be getting a feast to help them grow, but the misery resulting from this feast often leads the patient to discontinue the prebiotics. However, since xylooligosaccharides can effectively stimulate the growth of probiotics at lower doses, the unpleasant side effects of most other prebiotics are not present. Patients may be more likely to continue taking xylooligosaccharides, and their commensal bacteria will be happy for the ongoing food source.
- Slavin, Joanne. “Fiber and Prebiotics: Mechanisms and Health Benefits” Nutrients. 2013 Apr; 5(4): 1417–1435. Published online 2013 Apr 22. doi: 10.3390/nu5041417 PMCID: PMC3705355 PMID: 23609775
- “Xylooligosaccharides, a New Kind of Prebiotic”. Designs for Health. December 20, 2018