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Mary Ellen Sanders PhD Comment ID #58

Submitted 09/03/2013

Scientists representing International Scientific Association for Probiotics and Prebiotics (ISAPP) have proposed that the 2015 US Dietary Guidelines Advisory Committee consider live microbes and probiotics as part of the healthy, American diet. This further proposal supports the use of prebiotics, both in terms of fortifying beneficial components of the indigenous human microbiota, as well as adding to daily fiber intake.

Given their safe and straightforward ease of use, natural occurrence and health promoting properties, we propose that DGAC consider the question “What is the feasibility for dietary prebiotics to promote intestinal health, improve bone mineral density, and contribute to body weight management?”

A dietary prebiotic is ‘‘a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health’’ (Gibson et al., 2010). The inulin-type fructans [including fructooligosaccharides (FOS) and inulin] and galactooligosaccharides (GOS) are examples of confirmed prebiotics. Current criteria for classification as a prebiotic are:
• resists gastric acidity, hydrolysis by mammalian enzymes and gastrointestinal absorption
• is fermented by intestinal microbiota
• selectively stimulates the growth and/or activity of intestinal bacteria associated with health and well-being.
The biological and clinical importance of resident gastrointestinal microbiota in humans is becoming increasingly recognized. Since the gut microbiota contains pathogenic groups, as well as those set to improve health, prebiotics selectively target the latter. For instance, bifidobacteria and lactobacilli (the main target genera for prebiotics) can help resistance to gut infections by directly inhibiting the growth of harmful bacteria, reduce cholesterol levels, sustain the immune response and synthesize vitamins (Steer et al., 2000). Furthermore, consensus is building that the metabolic functions of the colonizing microbes are at least as important as the populations that are present (Backhed et al. 2012). Since not all bacterial metabolism is favorable, prebiotics are important as they encourage healthy metabolic function of the colonizing bacteria.

An authentic prebiotic must be validated through in vivo trials and the test ingredient should, at an appropriate dose, be reasonably certain to be free from harmful side effects. Structure and size are important attributes of confirmed prebiotics. Moreover, as they are carbohydrate compounds, resist digestion in the human small intestine and are principally fermented in the lower bowel, they are dietary fiber substances and therefore generate effects upon intestinal transit and fecal bulking (Slavin, 2013). Since the U.S. recommended daily fiber intake is 25-38g, but only an average of 15g is consumed (American Dietetic Association), recommending dietary prebiotics could positively impact total fiber intake.

Prebiotic research has continued at a rapid pace recently (>1000 published research articles in the past 5 years). Several avenues of human health-related research have been addressed. These include:

• Effects within the gut ecosystem
o Reduced duration, incidence and symptoms of traveller’s diarrhea (Cummings et al., 2001; Drakoularakou et al., 2010)
o Reduced episodes of diarrhea in subjects with Clostridium difficile-induced diarrhea (Lewis et al., 2005)
o Improved symptomology and gut microbiota composition in Irritable Bowel Syndrome (Silk et al., 2009)
o Favorable shifts in chronic intestinal inflammation, with relevance for Inflammatory Bowel Disease (Leenen and Dieleman, 2007)
• Influences that are systemic to the gut
o Improved mineral absorption and bone mineral density (Abrams et al., 2007; Holloway et al., 2007)
o Reduction in energy intake and markers of insulin resistance and improved body weight management (Parnell and Reimer, 2009; Vulevic et al., 2013)
o Increased satiety and reduced appetite (Cani et al., 2006, 2009)
Our view is that several lines of evidence point towards improved nutritional well being following prebiotic ingestion due to their fiber effects, beneficial influence on metabolic functions and reducing the risk of certain disorders associated with the gut. Therefore, we support the idea that dietary recommendations should include foods rich in prebiotic carbohydrates, such as banana, onion, chicory, artichoke, asparagus, leek and garlic, as a part of a healthy, American diet. We therefore propose that DGAC consider the question ““What is the feasibility for dietary prebiotics to promote intestinal health, improve bone mineral density, and contribute to body weight management?”

Affiliation: Professional Association Organization: International Scientific Association for Probiotics and Prebiotics
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