Clinical Sciences Novartis Medical Nutrition Global Research and Development St. Louis Park, MN
Health Sciences Research Institute Germans Trias i Pujol Foundation Badalona, Spain
Kantonalspital Liestal Liestal, Switzerland To the Editor: Nutrition in Clinical Practice recently published an invited review by Roy et al entitled, "Short-Chain Fatty Acids: Ready for Prime Time?"1 This is a timely topic because the role of short-chain fatty acids (SCFA) in human health and disease is of great interest among nutritionists and healthcare practitioners. The authors reviewed both the known and expected benefits of SCFA. Several fermentable fibers are cited as excellent substrates for production of SCFA. However, the authors completely ignored the evidence published in peer-reviewed journals regarding partially hydrolyzed guar gum (PHGG), an excellent substrate for SCFA production. As a result of the omission, the article fails to inform readers of NCP about well-documented and accepted clinical benefits of PHGG, which is commonly used in medical nutrition products. We agree with the authors that butyrate "is the SCFA `par excellence'" because of its various physiologic benefits. PHGG has been shown to produce more butyrate than several other commonly used fermentable fibers such as fructooligosaccharides (FOS), inulin, hydrolyzed inulin, and soy oligosaccharides.2 In one study, the total production of SCFA from PHGG was superior to psyllium husk, methylcellulose, indigestible dextran, arabinogalactan, and polydextrose.3 In the diarrheal disorders section of the review, the authors state that "Reports from developing countries suggest that oral rehydration solutions (ORS) should be supplemented with [oligosaccharides] OS, thereby providing a scientific validation of our grandmothers' carrot soup and rice water...." No reference is provided for this statement. However, once again, the authors did not include relevant studies conducted at the International Center for Diarrheal Disease Research (ICDDR) in Bangladesh in which the benefits of PHGG added to ORS were investigated.4,5 The first study by Alam et al4 demonstrated a reduction in duration of acute diarrhea when PHGG was added to ORS when compared with a nonfiber ORS control formula. The second study by Alam et al5 demonstrated that addition of PHGG to comminuted chicken produced a significant reduction in the duration of persistent diarrhea. The authors reported that conclusive data are not yet available on the use of OS for prophylaxis against diarrhea during tube feeding. The strength of evidence for fiber-containing tube feeding formulas has merited a grade A recommendation in European Society of Parenteral and Enteral Nutrition (ESPEN) guidelines for management of diarrhea in elderly patients receiving enteral nutrition.6 The effectiveness of PHGG in the management of diarrhea duration and severity during the provision of enteral nutrition is supported by several published studies. Studies by Homan et al,7 Spapen et al,8 Nakao et al,9 and Rushdi et al10 have all shown that PHGG reduces the incidence of diarrhea in patients given enteral nutrition. Further, the benefits of PHGG span beyond diarrhea management. Parisi et al11 showed that PHGG was as effective as bran-fiber supplementation in significantly reducing irritable bowel syndrome (IBS) symptoms and was better tolerated by patients and easier to administer than bran fiber. Parisi et al12 also showed that PHGG produced beneficial effects over a short period (1-month administration) in core IBS symptoms and psychological aspects related to IBS. Giaccari et al13 showed positive results in evacuation frequency by week 12 and a decrease in frequency of flatulence, abdominal tension, and abdominal spasm by week 3 in IBS patients. The role of PHGG in the treatment of IBS was recently reviewed by Giannini et al,14 who concluded that supplementation with PHGG can lessen symptoms in patients with diarrhea and with constipation-predominant IBS. Finally, in Table 4, the authors did not include several products in the United States that contain FOS, such as Peptinex DT with Prebiotics, Diabetasource AC, Resource Diabetic TF, Boost Diabetic, and Boost with Benefiber and FOS (all from Novartis Nutrition Corporation, Minneapolis, MN). These products should have also been included in Table 4 of Roy et al.1 In closing, we compliment the editors for their insight of choosing a timely topic for an invited review. Unfortunately, it is not clear how the authors selected the information to include, and thus, the review failed to include important practical information for the readers of NCP and also for the patients that can benefit from its use. The inclusion of data that show clinical benefit in large part due to SCFA would have enhanced the thoroughness of this review.
The author responds: Greenberg, Gassult, and Meier rightly comment that our review on short-chain fatty acids (SCFA) short-changed guar gum as a substrate for SCFA and as a beneficial prebiotic when added to oral rehydration solutions in developing countries, in enteral nutrition solutions for diarrhea in the elderly, and when given for irritable bowel syndrome. The charge given to us by the Editor was to "review the effects and potential benefits of SCFA in nutrition support." Guar gum is mentioned as a fermentation substrate but only in the general context of other substrates such as resistant starch, pectins, gum arabic etc. Limitation of space prevented us from discussing the specific properties of each source of SCFA. More attention was given to inulin and oligofructose since they have been the topic of a large number of clinical studies. However, we did alert readers to the fact that some companies use hydrolyzed guar gum instead of inulin, GOS, and FOS as a soluble fiber in their enteral products. We are grateful to the authors of this letter for informing us about several products containing FOS which were not tabulated. Yours sincerely, Claude C. Roy, MD
Nutrition in Clinical Practice, Vol. 21, No. 6,
639-640 (2006)
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