George C Fahey

George C Fahey
University of Illinois, Urbana-Champaign | UIUC · Department of Animal Sciences

Doctor of Philosophy

About

455
Publications
113,504
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27,484
Citations
Citations since 2016
23 Research Items
10487 Citations
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Introduction
I work as a consultant in the pet animal nutrition and health space. In addition, I consult on matters related to dietary carbohydrates as regards human nutrition. I am advisor to the ILSI Carbohydrate Committee, and am on the Editorial Board of two journals. I am a frequent GRAS expert panel member.

Publications

Publications (455)
Article
It has been nearly 31 years since the International Symposium on Forage Cell Wall Structure and Digestibility was held in Madison, WI. The text resulting from that symposium, first published in 1993, has been an invaluable resource for animal and plant scientists alike but, unfortunately, has yet to be updated. Symposium organizers recognized that...
Article
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Human intestinal enzymes do not hydrolyze non-digestible carbohydrates (NDCs), and thus, they are not digested and absorbed in the small intestine. Instead, NDCs are partially to completely fermented by the intestinal microbiota. Select NDCs are associated with health benefits such as laxation, and blood cholesterol and glucose-lowering effects. ND...
Article
Objective The prebiotic fiber inulin has been studied in individuals undergoing hemodialysis (HD) due to its ability to reduce gut microbiota-derived uremic toxins. However, studies examining the effects of inulin on the gut microbiota and derived metabolites are limited in these patients. We aimed to assess the impact of a 4-week supplementation o...
Article
The fiber component of the diet is the major food source for the intestinal microbiota of swine. Included are traditional insoluble (e.g., cellulose) and soluble (e.g., pectin) dietary fibers, resistant starches (four types), and oligosaccharides (some of which are “prebiotics”). Fiber constituents are found both in the primary and secondary cell w...
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Traditional feed composition tables have been a useful tool in the field of animal nutrition throughout the last 70 years. The objective of this paper is to discuss challenges and opportunities associated with creating large feed ingredient composition tables. This manuscript will focus on three topics discussed during the National Animal Nutrition...
Article
Background: Treatment guidelines for chronic idiopathic constipation (CIC) recommend an "increase in fiber intake" as a first-line therapy, but most epidemiologic studies fail to support an association between a high-fiber diet and a reduced risk of constipation. Furthermore, randomized controlled clinical studies show that most isolated fibers (e...
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In recent years, it has become increasingly obvious that dietary fiber or nondigestible carbohydrate (NDC) consumption is critical for maintaining optimal health and managing symptoms of metabolic disease. In accordance with this, the US FDA released its first official definition of dietary fiber in 2016 for regulation of Nutrition and Supplement F...
Article
Recent data has supported a role for the gut microbiota in improving cognition and shaping behavior. Here, we assessed whether pectin, a soluble, fermentable fiber, could enhance learning and memory in mice. Two cohorts of young male C57Bl/6 J mice, C1 (n = 20) and C2 (n = 20), were obtained from Jackson Laboratory and randomized to semi-purified A...
Article
A two-day workshop organized by NIH and USDA included 16 presentations focused on the role of diet in alterations of the human gastrointestinal microbiome, primarily that of the colon. Although thousands of projects have been funded by United States federal funding agencies to study the intestinal microbiome of humans and a variety of animal models...
Article
Background: Because of its chemical complexity, the estimation of dietary fiber content of feed and food materials is a difficult analytical challenge. Three major fiber analyses are conducted routinely in the United States including crude fiber (CF), detergent fiber, and total dietary fiber (TDF). Objective: Factors crucial to the successful measu...
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Seasonal changes in the foodscape force herbivores to select different plant species or plant parts to meet nutritional requirements. We examined whether the search for calorie-rich carbohydrates explained giant panda's selection for bamboo culm over leaves during spring. Leaves and culms were collected from four Phyllostachys bamboos (P. aurea, P....
Article
Butyrate possesses negative sensory qualities and is most effectively utilized in the intestine to provide energy to the colonocyte for the maintenance of intestinal health. Butyrate has also shown promise in the treatment of intestinal disorders and diseases such as short bowel syndrome, inflammatory bowel disease, and colon cancer. To modify sens...
Article
Introduction Recent data indicates that environmental conditions early in life can alter behavioral outcomes and responses to dietary interventions in model experiments. The gut microbiota may mediate such differences. Methods Two cohorts, C1 (n = 20) and C2 (n = 20), of C57Bl/6J mice were randomized to a 5% pectin (n = 20) or cellulose diet (n =...
Article
Animal proteins are commonly used in extruded dog foods. Plant-based proteins have a more consistent nutrient profile than animal sources but may contain antinutritional factors, including trypsin inhibitors and oligosaccharides. Bioprocessed soy protein (SP; HP-300; Hamlet Protein, Inc., Findlay, OH) is a processed soy-based product with low antin...
Article
Animal proteins are commonly used in extruded dog foods. Plant-based proteins have a more consistent nutrient profile than animal sources but may contain antinutritional factors, including trypsin inhibitors and oligosaccharides. Bioprocessed soy protein (SP; HP-300; Hamlet Protein, Inc., Findlay, OH) is a processed soy-based product with low antin...
Article
The objectives were to examine in vitro fermentation characteristics, in vivo nutrient digestibility, fecal microbiota, and serum lipid profiles as affected by α-cyclodextrin (ACD) supplementation. Short-chain fatty acid (SCFA) production was measured after in vitro fermentation for 3, 6, 9, and 12 h of ACD, β-cyclodextrin, and γ-cyclodextrin. Five...
Article
The objectives were to examine in vitro fermentation characteristics, in vivo nutrient digestibility, fecal microbiota, and serum lipid profiles as affected by α-cyclodextrin (ACD) supplementation. Short-chain fatty acid (SCFA) production was measured after in vitro fermentation for 3, 6, 9, and 12 h of ACD, β-cyclodextrin, and γ-cyclodextrin. Five...
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Our objective was to measure the proximate, starch, amino acid, and mineral compositions of grains, grain co-products, and other carbohydrate sources with potential use in pet foods. Thirty-two samples from barley (barley flake, cut barley, ground pearled barley, malted barley, whole pearled barley, pearled barley flakes, and steamed rolled barley)...
Article
Pet owners have increasing concerns about the nutrition of their pets, and they desire foods and treats that are safe, traceable, and of high nutritive value. To meet these high expectations, detailed chemical composition characterization of ingredients well beyond that provided by proximate analysis will be required, as will information about host...
Article
Purified xylooligosaccharides from Miscanthus x giganteus (MxG XOS) were used in an in vitro fermentation experiment inoculated with human fecal microbiota. A commercial XOS product and pectin were used as controls. Decreases in pH by 2.3, 2.4, and 2.0 units and production of short-chain fatty acids (SCFA; acetic acid: 7764.2, 6664.1, 6387.9 µmol/g...
Article
Objective: Simplification of diets, low in variety but high in energy, contributes to the loss in diversity observed in the obese gastrointestinal (GI) microbiome. A novel GI microbiome modulator (GIMM) as a dietary intervention was developed. Methods: Mice were fed either an obesogenic diet (ObD) or an ObD containing 15% activated soy pod fiber...
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Prebiotics resist digestion, providing fermentable substrates for select gastrointestinal bacteria associated with health and well-being. Agave inulin differs from other inulin type fibers in chemical structure and botanical origin. Preclinical animal research suggests these differences affect bacterial utilization and physiologic outcomes. Thus, r...
Article
INTRODUCTION Prebiotic fibers in pet foods are becoming increas­ ingly popular due to their favorable effects on gut function and health by increased production of short-chain fatty acids (SCFA) and changes in the intestinal microbiota (Propst et al., 2003). Most prebiotic fibers are rapidly fermentable and, if added at high concen­ trations to the...
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The objectives were to quantify gastrointestinal tolerance, total tract nutrient digestibility, and serum lipid profiles of dogs as affected by α-cyclodextrin (ACD) supplementation and to validate the accuracy of fat analyses techniques using novel ACD-fat complexes. The ACD was hydrolyzed and free sugars and hydrolyzed monosaccharides were quantif...
Article
Dietary fermentable fiber is known to benefit intestinal health of companion animals. Soluble corn fiber (SCF) was evaluated for its chemical composition, nitrogen-corrected true ME (TMEn) content, in vitro digestion and fermentation characteristics, and in vivo effects on nutrient digestibility, fecal fermentation end products, and modulation of t...
Article
The objectives were to quantify gastrointestinal tolerance, total tract nutrient digestibility, and serum lipid profiles of dogs as affected by α-cyclodextrin (ACD) supplementation and to validate the accuracy of fat analyses techniques using novel ACD-fat complexes. The ACD was hydrolyzed and free sugars and hydrolyzed monosaccharides were quantif...
Article
Full-text available
During the annual period of bamboo shoot growth in spring, free-ranging giant pandas feed almost exclusively on the shoots while ignoring the leaves and full- height culm. Little is known about the nutritional changes that occur during bamboo shoot growth, if nutritional changes differ among species, or how these changes might influence forage sele...
Article
The objective of this experiment was to determine the effects of in vitro fermentation of coconut endosperm fiber (CEF), chicory pulp (CHP), and selective blends of these substrates on SCFA production and changes in microbiota using canine fecal inocula. A total of 6 individual substrates, including short-chain fructooligosaccharide (scFOS; a welle...
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In our published randomized, double-blind, placebo-controlled, 3-period crossover trial, healthy adult men (n = 21) consumed bars containing no supplemental fiber (placebo; NFC), polydextrose (21 g/d), and soluble corn fiber (SCF; 21 g/d) for 21 d each. Fecal specimens were collected between days 16 and 21 for fermentative end-product analysis and...
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Inclusion of fermentable fibres in the diet can have an impact on the hindgut microbiome and provide numerous health benefits to the host. Potato fibre (PF), a co-product of potato starch isolation, has a favourable chemical composition of pectins, resistant and digestible starch, cellulose, and hemicelluloses. The objective of the present study wa...
Article
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Fructan supplementation of a commercially available canned cat food was evaluated using senior (≥ 9 yr) cats to assess nitrogen (N) partitioning in excreta and stool metabolite and microbiota concentrations. Oligofructose (OF) or SynergyC (OF+IN) were added to the diet individually at 1% (dry weight basis). Cats were acclimated to the control diet...
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Pet owners desire treats with adequate nutritional profiles, functional benefits, long-lasting properties and an interactive nature. Therefore, it is pivotal to understand the digestion characteristics of treats produced by different processing methods and having variable nutritional composition. The objective of the present study was to measure in...
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The objective of this research was to measure in vitro hydrolytic digestion, glycemic and insulinemic responses in dogs, and true ME (TMEn) content of select soluble corn fibers (SCF) in roosters. The first generation (G1) SCF included hydrochloric acid-treated corn syrup (G1-CS-HCl), an SCF with an increased total dietary fiber (TDF) content (G1-S...
Article
This study examined the following: effects of simulated firefighting (FF) activities under heat stress on sustained attention; whether incident rehabilitation (IR) influences performance; and relationships between performance, affect and personality. Firefighters performed ∼18 min of FF. Attention, physiological, perceptual and psychological assess...
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Little clinical research exists on agave inulin as a fiber source. Due to differences in botanical origin and chemical structure compared to other inulin-type fibers, research is needed to assess gastrointestinal (GI) tolerance following consumption. This study aimed to evaluate GI tolerance and utilization of 5.0 and 7.5 g per day of agave inulin...
Article
Nontargeted metabolomics analyses were used (1) to compare fecal metabolite profiles of healthy breast-fed (BF) and formula-fed (FF) infants before and during in vitro fermentation in batch culture and (2) to evaluate fecal metabolomics in assessing infant diet. Samples from healthy BF (n = 4) or FF (n = 4) infants were individually incubated at 37...
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The impact of human milk oligosaccharides (HMO) on mucosal immunity, gut microbiota and response to rotavirus (RV) infection was investigated in the piglet model. Newborn piglets were fed with formula alone (FF) or formula supplemented with 4 g l(-1) HMO (HMO) or a prebiotic mixture of 9:1 short-chain galactooligosaccharides (3.6 g l(-1)) and long-...
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Sled dogs commonly suffer from diarrhea. Although multiple etiologies exist there are limited field studies using synbiotics as a supplement to prevent or treat diarrhea. The objective of this study was to examine alterations in fecal quality, short-chain fatty acids (SCFA), and the fecal microbiome in two groups of training sled dogs fed a synbiot...
Article
The objective of this study was to compare two in vivo methods using pigs and roosters and an in vitro method for determining the caloric value of four fiber sources [i.e., two resistant starches (RS 60 and RS 75), soluble corn fiber (SCF 70), and pullulan]. Metabolizable energy (ME) in pigs and true metabolizable energy (TMEn) in roosters were det...
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In October 2012, a group of scientists met at the 10th Meeting of the International Scientific Association of Probiotics and Prebiotics (ISAPP) in Cork, Ireland to discuss issues surrounding prebiotics and their development. This article summarises outputs from the meeting. Various prebiotic definitions were discussed and how the concept has evolv...
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Potato fiber (PF), a co-product of potato starch manufacture, was evaluated as a potential novel fiber source in dog food. Potato fiber contained 55% total dietary fiber, 29% starch, 4% crude protein, and 2% acid-hydrolyzed fat. The PF substrate was evaluated for chemical composition, in vitro digestion and fermentation characteristics, and in vivo...
Article
A primary function of the gastrointestinal tract is to provide the body with water, electrolytes and nutrients. It accomplishes this by ingestion, mechanical shearing, mixing and movement of the food through the gastrointestinal tract (motor events), secretion of digestive juices (≈ 6 liters per day) for degradation of complex nutrients into simple...
Article
Approximately 45-50% of all duty-related deaths among firefighters are due to sudden cardiovascular events and a disproportionate number of these fatalities occur following strenuous fire suppression activities. To evaluate the effect of strenuous firefighting activities on platelets, coagulation and fibrinolytic activity and to document the extent...
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The US has a pet population of approximately 70 million dogs and 74 million cats. Humans have developed a strong emotional bond with companion animals. As a consequence, pet owners seek ways to improve health, quality of life and longevity of their pets. Advances in canine and feline nutrition have contributed to improved longevity and well-being....
Article
The apparent total tract and ileal digestibility assays to measure AA absorption in commercial canine diets was compared in the present study. Five ileal cannulated dogs were fed 5 commercial dry canine foods selected to contain 19 to 30% CP in a 5 × 5 Latin square design. Ileal and total tract digestibility (apparent and standardized) of DM, OM, C...
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Studies of whole grain and chronic disease have often included bran-enriched foods and other ingredients that do not meet the current definition of whole grains. Therefore, we assessed the literature to test whether whole grains alone had benefits on these diseases. The objective was to assess the contribution of bran or cereal fiber on the impact...
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The objective of these experiments was to measure in vitro hydrolytic digestion and glycemic and insulinemic responses of select carbohydrate blends, all containing the novel carbohydrate, soluble corn fiber (SCF). Two SCF that varied in their method of production were used to formulate the carbohydrate blends. One set of blends contained a SCF tha...
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Colonization of the intestinal microbiota after birth plays an important role in development of the neonatal gastrointestinal and immune systems. Two key environmental factors that influence the colonization pattern are delivery mode and nutrition. In this study, the impact of delivery mode and nutrition on microbial colonization and metabolic acti...
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Dietary fibre has been a subject of study in companion animal nutrition for approximately 25 years, recently focusing on its benefits for dog and cat health and well-being. Pet animal diets contain significant amounts of carbohydrates, including dietary fibre. Depending on the properties of carbohydrates and their level in the diet, different physi...
Article
This study sought to determine fermentation potential of human milk oligosaccharides by mixed cultures of fecal microbiota from breast-fed (BF; n=4) and formula-fed (FF; n=4) infants. Infant fecal inocula were incubated with galactooligosaccharide (GOS), gum arabic (GA), HP inulin (HP), 2'-fucosyllactose (2'FL), 6'-sialyllactose (6'SL), and lacto-N...
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The objective of this study was to evaluate health outcomes resulting from dietary supplementation of novel, low-digestible carbohydrates in the cecum and colon of Sprague-Dawley rats randomly assigned to one of four treatment groups for 21 days: 5% cellulose (Control), Pectin, soluble fiber dextrin (SFD), or soluble corn fiber (SCF). Rats fed Pect...
Article
Guar gum and partially hydrolyzed guar gum (PHGG) are food ingredients that have been available for many years. PHGG is the partially hydrolyzed product produced from guar gum obtained from the Indian cluster bean (Cyanopsis tetragonolopus). The gum (CAS RN 9000-30-0) is composed of galactomannan, a gel-forming polysaccharide with a molecular weigh...
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Fermentable oligosaccharides, particularly those found in soybean meal (SBM), may modulate fermentation in the ceca, thus affecting intestinal immune responses to intestinal pathogens. We hypothesized that fermentable oligosaccharides found in SBM would positively affect cecal fermentation and intestinal immune status in chicks challenged with an a...
Chapter
Probiotics are marketed in the human food sector as being beneficial to gut health. As is often the case, this led to similar trends in the pet food and supplement markets. Although it is difficult to incorporate probiotics into pet diets because of processing problems, supplements and diets containing probiotics are now available. There is limited...
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Purpose: This review focuses on the health benefits of viscous versus nonvis-cous soluble fibers, why symptoms can occur with increased fiber consumption , and how to avoid symptoms to improve adherence with a high-fiber diet.
Article
Four healthy adult cats were used in a crossover design to determine phylogeny and metabolic functional capacity of the cat's gastrointestinal microbiota using a metagenomic approach. Healthy adult cats (1.7 y old) were fed diets containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d, at which time fresh fecal samples were collec...
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Chews are an important part of the pet product industry, with many having potential benefits to decrease plaques or calculus formation. However, their digestion characteristics and gut transit time are virtually unknown. Two experiments were conducted to determine in vitro DM digestibility of expanded pork skin chews and rawhide chews, and apparent...
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Fermentable carbohydrates may enhance the ability of the gastrointestinal tract to defend against a pathogenic infection. We hypothesized that a galactoglucomannan oligosaccharide-arabinoxylan (GGMO-AX) complex would positively affect immune status and prevent colonization and shedding in Salmonella typhimurium-infected chicks. Using a completely r...
Article
This review focuses on the health benefits of viscous versus nonviscous soluble fibers, why symptoms can occur with increased fiber consumption, and how to avoid symptoms to improve adherence with a high-fiber diet. Review of scientific literature as well as evidence-based guidelines and resources. While it is generally known that "fiber is good fo...
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The relative contribution of novel fibers such as polydextrose and soluble corn fiber (SCF) to the human gut microbiome and its association with host physiology has not been well studied. This study was conducted to test the impact of polydextrose and SCF on the composition of the human gut microbiota using 454 pyrosequencing and to identify associ...
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Fermentable carbohydrates may enhance the ability of the gastrointestinal tract to defend against pathogenic infection. We hypothesized that a mannose-rich, galactoglucomannan oligosaccharide-arabinoxylan (GGMO-AX) complex would positively impact immune status and prevent weight loss resulting from acute coccidiosis (Eimeria acervulina) infection o...
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The microbial composition and in vitro fermentation characteristics of human milk oligosaccharides (HMO), lacto-N-neotetraose (LNnT), a 2:1 mixture of polydextrose (PDX) and galactooligosaccharides (GOS), and short-chain fructooligosaccharides (scFOS) by pooled ascending colonic microbiota from 9- and 17-d-old formula-fed (FF) and sow-reared (SR) p...
Chapter
The food industry is constantly shifting focus based on what is most important to the consumer. Products are marketed currently that are believed to provide health benefits to the consumer such as beneficial effects on health or as disease preventatives. Much of the focus is on oligosaccharides as health-promoting substrates. Many oligosaccharides...
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Fish proteins have been reported to be more satiating than meat proteins. The objective was to determine the effect of different animal protein pre-meals on satiety. A total of ten intact female hounds were fed pork loin, beef loin, chicken breast, salmon fillet or pollock fillet. Each pre-meal was fed to contain 100 g protein. Blood was collected...
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The objective of the present study was to evaluate digestive physiological outcomes elicited by functional fibres fed to healthy adult men. A total of twenty-one healthy adult men were utilised in a cross-over design. Each subject received polydextrose (PDX) or soluble maize fibre (SCF) (21 g/d) or no supplemental fibre (no fibre control; NFC) in a...