Researching Prebiotics and Probiotics
August 2011/Prepared Foods -- Consumers interested in improving their body’s absorption of specific minerals, improving immune health, alleviating the symptoms associated with irritable bowel syndrome and supporting general wellness are turning to prebiotics and probiotics. And, growing interest combined with emerging research means this area of functional food products is poised for continued growth.
A selection of studies show calcium absorption improvements with 5g and 10g/day lactulose, 20g/day trans-galacto-oligosaccharides and 10g/day of a long-chain inulin and oligofructose mixture.
Prebiotics are non-digestible food ingredients that benefit the host by selectively stimulating the growth and/or activity of one or more bacteria in the colon1. Galacto-oligosaccharides (GOS), inulin and “inulin-type” probiotics, including fructo-oligosaccharides (FOS) and oligofructose, are the most common prebiotics in functional food products.
Inulin and the inulin-type prebiotics are soluble fibers that are naturally found in Jerusalem artichokes, burdock, chicory, leeks and onions. Commercially available inulin-type prebiotics are typically extracted from chicory root or synthesized from sucrose. They are sometimes used as fat and sugar replacers and resist digestion in the upper gastrointestinal tract and undergo bacterial fermentation in the colon, where they stimulate the growth of Bifidobacteria species2. Additionally, inulin and inulin-type fructans have the potential to enhance mineral absorption and decrease serum triacylglycerols3.
Some studies indicate inulin and inulin-type fructans improve calcium absorption, especially in post-menopausal women, where 5g and 10g of lactulose per day, 20g of trans-galacto-oligosaccharides per day, 4g of chicory fructan fiber given twice per day, and a 10g/day mixture of long-chain inulin and oligofructose have all been shown to significantly increase calcium absorption in studies in post-menopausal women4,5,6,7. In addition to enhancing calcium, some prebiotics, notably FOS, may enhance the absorption of magnesium and copper8,9.
In addition to their potential to enhance calcium absorption, prebiotics may play a role in reducing serum triacylglycerols and improving some measures of blood glucose. A meta-analysis of 15 randomized, controlled trials examining the effect of inulin and oligofructose on serum triacylglycerols found consumption of these prebiotics was associated with a significant decrease in serum triacylglycerols of 0.17mmol/L10.
FOS, the short-chain, inulin-type fructan mixes synthesized from sucrose, may help with some measures of blood glucose control--though not all trials show a consistent benefit. In a randomized, controlled trial, 10.6g of FOS helped decrease the postprandial insulin response in adults with mild hyperlipidemia11. And, 8g of FOS daily for 14 days resulted in an 8% reduction in fasting blood glucose in poorly controlled type 2 diabetes12.
The most common side effects associated with inulin-type prebiotics include gas, cramping and bloating. Bloating may occur in some individuals with even small doses (2.5-5g/day), whereas bloating and cramping typically only occur with doses over 40g/day13.
Probiotics: Multifunctional Health Providers
Probiotics are “live microorganisms, which, when administered in adequate amounts, confer a benefit to the host”14. They can provide numerous health benefits, if the right strain is incorporated into a viable food or beverage product, and the consumer follows proper dosing guidelines (which can vary widely). However, each strain of probiotics has a different effect, and no two probiotics are alike15. Therefore, the research-backed benefits of one probiotic strain cannot be applied to other strains or even different preparations of the same species or strain16.
The majority of probiotics are similar to bacterium that is naturally found in the human gut. The bacteria typically come from Lactobacillus or Bifidobacterium and, within these groups, there are different species and strains. In addition to bacteria, some yeast are probiotics, such as Saccharomyces boulardii.
Though there is already good bacteria present in the human gut, the balance of microorganisms can be thrown off by antibiotic use and invasion by harmful bacteria, yeasts, fungi and parasites, making probiotics a viable option for enhancing healthy gut bacteria.
The top areas with supporting research for probiotic use include decreasing the duration of diarrhea, improving immune system functioning, helping alleviate some of the symptoms associated with irritable bowel syndrome and impacting weight management.
• Diarrhea. A meta-analysis of 63 studies with a total of 8,014 participants found that a variety of probiotic strains reduced the duration of diarrhea with no significant side effects noted17. Saccharomyces boulardii and Lactobacilli are two probiotics that have been used to prevent antibiotic-associated diarrhea18. A meta-analysis also found that Saccharomyces boulardii is efficacious for antibiotic-associated diarrhea and traveler’s diarrhea, as well as reducing Helicobacter pylori treatment-related symptoms19.
In infants and young children, probiotics have a moderate effect in reducing incidence of diarrhea (by about 1 day) and appear to be strain-dependent, dose-dependent (greater for doses >1010–1011 colony-forming units (CFU/day) and best when treatment is initiated early, during the course of diarrhea. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition and European Society of Paediatric Infectious Diseases Expert Working Group have stated that probiotics with proven efficacy, including Lactobacillus rhamnosus GG and Saccharomyces boulardii, may be used as an adjunct therapy for kids with acute gastroenteritis being given rehydration therapy20.
• Immune functioning. The majority of the immune system is located within the gut. Therefore, the mix of bacteria may affect immune functioning. And, some studies indicate probiotic supplementation positively alters various aspects of immune functioning, though additional in vivo research is necessary to determine the clinical significance of probiotic-induced immune system modulation21.
• Irritable Bowel Syndrome (IBS). IBS is a gastrointestinal disorder characterized by abdominal pain and altered bowel habits. An estimated 10-20% of the population has IBS and, in most parts of the world, women are affected more than men. Approximately 10-30% of those with IBS seek medical care22.
Changes in gastrointestinal microbiota have been noted in those with IBS, suggesting that probiotics may be beneficial23. A multispecies probiotic supplement composed of 1×107 CFU/ml each of Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium animalis ssp. lactis Bb12 had a beneficial effect on the severity of IBS symptoms, notably distension, abdominal pain and bowel symptoms, quality-of-life and stability of intestinal microbiota in the probiotic vs. placebo group in a randomized, placebo-controlled 5-month intervention in 86 patients.
Another randomized, double-blind, placebo-controlled study in 141 children with IBS found that Lactobacillus rhamnosus, given for a period of 8 weeks, significantly reduced the frequency and severity of abdominal pain. Finally, Saccharomyces boulardii helped reduce the daily number of stools in IBS patients and improved symptoms to a greater extent than placebo in a randomized trial with 34 patients24.
• Obesity. Animal studies indicate that alterations in gut microflora may contribute to obesity,25 and, therefore, specific prebiotics and probiotics may be beneficial for weight management in humans, although more research is needed in this area.
A recently published study of rats found supplementation with either Lactobacillus plantarum or Escherichia coli helped prevent obesity and reduce low-level inflammation in rats fed a high-calorie diet, although Lactobacillus plantarum had a greater impact on preventing weight gain26.
Though there are many probiotics that can be incorporated into foods and beverages, a few stand out with good safety records. These include Lactobacillus, Bifidobacterium, Streptococcus thermophilus and Saccharomyces. Many other probiotics may be safe, though more research is needed to determine their safety. Also, immunocompromised patients or those with compromised gut integrity, young children and the elderly should use caution when consuming probiotics, especially those without a well-established safety record.
When selecting prebiotics and probiotics for formulation into food and beverage products, it is best to choose strains that have undergone the rigors of in vivo human trials for safety and efficacy. And, verify that the specific probiotic remains live and active in the desired food application through the end of shelflife. In addition to formulating with the right prebiotic or probiotic strain for the intended function, it is vital that food manufacturers outline proper use and convey the benefits of their product to their target consumer in easy to understand terms. One major benefit of formulating with prebiotics and probiotics is that many individuals notice an almost immediate difference after consuming them. pf
The Commercial Prebiotic Market
Global Industry Analysts Inc. forecasts the U.S. market for prebiotics will reach $225.1 million by 2015, with European sales predicted to reach $1.17 billion by that time. Similar predictions are obtained from Frost & Sullivan, which reports the market for prebiotics will double in next five years, to exceed $220 million. The June 1, 2011, lead feature of this magazine’s E-dition, titled “Preparing for Prebiotics,” reviews global trends and statistics for these specialized dietary fibers. See http://tinyurl.com/3n6owz4.