Effect of an extruded pea or rice diet on postprandial insulin and cardiovascular responses in dogs

Determining the effects of Candida utilis-fermented pea starch vs. unfermented pea starch, alone or in whole diets, on palatability and glycemic response in dogs and cats

Current research suggests yeast fermentation has the potential to improve palatability of pea-based diets for both cats and dogs. However, to be useful, fermentation should not compromise other healthy attributes of peas such as a low glycemic response. Fermentation of uncooked pea starch with Candida utilis (ATCC 9950) appeared to increase crude protein, crude fiber content, inorganic compounds (phosphorus and iron) and phenols. Whole diets were designed with fermented and unfermented pea starch to assess palatability, food intake, and glycemic responses in unacclimated, mixed sex Beagle dogs and mixed breed cats (n = 8 and n = 7, respectively). For palatability testing, a control diet was formulated with 30% corn starch as well as test diets with 30% inclusion of fermented or unfermented pea starch (all lab-made), then compared to a commercial diet containing pea starch (Legacy/Horizon). Fermentation had little effect on rapidly digestible starch either in uncooked starch form or when incorporated into whole diets, but did decrease resistant starch by 15% and increase slowly digestible starch by 20%. Palatability tests using either two choices or four choices at a time revealed a significant preference for the fermented pea starch diet (p < 0.01) in both species. For the glycemic responses, a total of four different pea products were included: unfermented pea starch, fermented pea starch, and 30% inclusion of unfermented and fermented pea starch in whole formulated diets. There were no significant changes in glycemic responses with the fermented pea diet compared to the unfermented diet, demonstrating that healthful low glycemic properties of pea starch were retained after C. utilis fermentation. Overall, C. utilis-fermentation technique was successfully adapted to pea starch where it resulted in increased palatability and food intake in dogs and cats, with potential to positively contribute to overall health benefits for both species.

Review: A species comparison of the kinetic homogeneous and heterogeneous organization of sodium-dependent glucose transport systems along the intestine

The targeted use of carbohydrates by feed and food industries to create balanced and cost-effective diets has generated a tremendous amount of research in carbohydrate digestion and absorption in different species. Specifically, this research has led us to a larger observation that identified different organizations of intestinal sodium-dependent glucose absorption across species, which has not been previously collated and reviewed. Thus, this review will compare the kinetic segregation of sodium-dependent glucose transport across the intestine of different species, which we have termed either homogeneous or heterogeneous systems. For instance, the pig follows a heterogeneous system of sodium-dependent glucose transport with a high-affinity, super-low-capacity (Ha/sLc) in the jejunum, and a high-affinity, super-high-capacity (Ha/sHc) in the ileum. This is achieved by multiple sodium-dependent glucose transporters contributing to each segment. In contrast, tilapia have a homogenous system characterized by high-affinity, high-capacity (Ha/Hc) throughout the intestine. Additionally, we are the first to report glucose transporter patterns across species presented from vertebrates to invertebrates. Finally, other kinetic transport systems are briefly covered to illustrate possible contributions/modulations to sodium-dependent glucose transporter organization. Overall, we present a new perspective on the organization of glucose absorption along the intestinal tract.

Brush border enzyme hydrolysis and glycaemic effects of isomaltulose compared to other saccharides in dogs

Digestible carbohydrates differ in glycaemic response, therewith having the potential to influence metabolic conditions such as insulin resistance and diabetes mellitus. Isomaltulose has been proven to lower the glycaemic response in humans, which to date has not been studied in dogs. Therefore, the aim of the present study was to characterise the digestibility, as well as the physiological effects of isomaltulose in dogs, in comparison to other saccharides. To this end, three studies were performed. Study 1 was an in vitro study, evaluating the small intestinal hydrolysis of isomaltulose compared to other relevant carbohydrate sources. Three of these saccharides, having close and low-moderate degrees of hydrolysis by brush border enzymes, were also evaluated in vivo for their glycaemic effects by measuring plasma levels of glucose, insulin and glucagon-like peptide 1 (GLP-1) 0-180 min after administration of a single dosage after an overnight fast (i.e., isomaltulose, sucrose and maltodextrin in a 3 × 3 Latin-square design, in 9 dogs, Study 2). To understand if digestive enzymes, underlying glycaemic responses for isomaltulose and sucrose can be upregulated, we exposed dogs to these saccharides for 2 weeks and repeated the measurements after an overnight fast in 18 dogs (Study 3). Isomaltulose was hydrolysed by intestinal enzyme preparation from all three dogs, but the degrading activity was low (e.g., 3.95 ± 1.03 times lower vs. sucrose), indicating a slower rate of hydrolysis. Isomaltulose had a low glycaemic response, in line with in vitro data. In vitro hydrolysis of sucrose was comparable or even higher than maltodextrin in contrast to the more pronounced glycaemic response to maltodextrin observed in vivo. The numerically higher blood glucose response to sucrose after continuous consumption, might indicate an adaptive response. In conclusion, the current work provides valuable insights into the digestion physiology of various saccharides in dogs. Further investigations on related benefits are thus warranted.

Effect of diet on postprandial glycemic and insulin responses in healthy dogs

Introduction

Dog owners have gradually changed their approach, paying more attention to the nutrition and health of their animals. Various pet foods with different ingredients and nutritional characteristics are available on the market. The present study aimed to evaluate the administration of three diets, namely, two grain-free (GF1 and GF2) and one grain-based (CB), with different sources of carbohydrates that can influence the glycemic and insulin postprandial responses in healthy dogs.

Materials

Fifteen healthy dogs were dived in three groups and alternatively fed each diet for 50 days. Blood samples were collected at beginning of each feeding period. Glycemia and insulin were measured before and after 120, 240 and 360 minutes diet administration to evaluate postprandial responses.

Results

GF2 diet showed the highest level of albumin and mean insulin concentration (p < 0.001). Furthermore, the GF1 diet caused the smallest (p < 0.001) glucose and insulin area under the curve (AUC) and the lowest (p < 0.05) glucose nadir. Otherwise, GF1 showed the highest (p < 0.01) insulin time to peak. The GF2 diet showed the highest level of albumin while reporting the lowest amount of fructosamine (p < 0.05). The diet GF2 registered the highest (p < 0.001) level of insulin zenith. The cereal-based (CB) diet reported the highest amount of fructosamine (p < 0.05). The CB diet had the highest levels of glucose and the highest (p < 0.001) glucose and insulin mean concentrations. Diet CB reported the lowest (p < 0.001) insulin nadir.

Discussion

Diets with different carbohydrate sources and chemical compositions could modulate the glycemic response in healthy dogs. Bearing in mind that glycemic/insulin postprandial responses influence energy availability and that different dogs have specific lifestyles, it may be preferable to also consider these aspects when choosing a maintenance diet for animals.

Nutritional Management of Cats and Dogs with Diabetes Mellitus

This article reviews the nutritional assessment and management of diabetic dogs and cats. It discusses how to determine appropriate nutritional goals for individual patients, including comorbid patients with diabetes. Considerations for macronutrient and micronutrient modifications will be reviewed.

Roles of plant-based ingredients and phytonutrients in canine nutrition and health

Dogs possess the ability to obtain essential nutrients, established by the Association of American Feed Control Officials (AAFCO), from both animal‐ and plant‐based ingredients. There has been a recent increase in the popularity of diets that limit or completely exclude certain plant‐based ingredients. Examples of these diets include ‘ancestral’ or ‘evolutionary’ diets, raw meat‐based diets and grain‐free diets. As compared to animal sources, plant‐derived ingredients (including vegetables, fruits, grains, legumes, nuts and seeds) provide many non‐essential phytonutrients with some data suggesting they confer health benefits. This review aims to assess the strength of current evidence on the relationship between the consumption of plant‐based foods and phytonutrients (such as plant‐derived carotenoids, polyphenols and phytosterols) and biomarkers of health and diseases (such as body weight/condition, gastrointestinal health, immune health, cardiovascular health, visual function and cognitive function) from clinical trials and epidemiological studies. This review highlights the potential nutritional and health benefits of including plant‐based ingredients as a part of balanced canine diets. We also highlight current research gaps in existing studies and provide future research directions to inform the impact of incorporating plant‐based ingredients in commercial or home‐prepared diets.

The Effects of 7 Days of Feeding Pulse-Based Diets on Digestibility, Glycemic Response and Taurine Levels in Domestic Dogs

Grain-based carbohydrate sources such as rice comprise 30–50% of commercial pet foods. Some pet foods however have removed the use of grains and have instead incorporated pulses, such as peas and lentils, resulting in grain-free diets. The hypothesis was dog diets with higher levels of dietary fiber will produce a low glycemic response due to decreased rates of digestion and lowered bioavailability of all macronutrients and increased fecal bile salt excretion. This in turn was hypothesized to produce lower plasma concentrations of cysteine, methionine and taurine after 7 days of feeding each test diet in dogs. Six diets were formulated at an inclusion level of 20% available carbohydrate, using white rice flour (grain) or whole pulse flours from smooth pea, fava bean, red lentil or 2 different wrinkled pea varieties (CDC 4,140–4 or Amigold) and fed to beagles in a randomized, cross-over, blinded design. After 7 days feeding each diet, fasting blood glucose was the lowest in the lentil (3.5 ± 0.1 mmol/L) and wrinkled pea (4,140–4; 3.6 ± 0.1 mmol/L) diet periods, while peak glucose levels was lowest after feeding the lentil diet (4.4 ± 0.1 mmol/L) compared to the rice diet. Total tract apparent digestibility of all macronutrients as well as taurine differed among diets yet plasma taurine was not outside normal range. Decreased macronutrient and amino acid digestibility was associated with increasing amylose and dietary fiber content but the specific causative agent could not be determined from this study. Surprisingly, digestibility decreases were not due to increased bile salt loss in the feces since increasing dietary fiber content led to decreased fecal bile salt levels. In conclusion, although pulse-based canine diets have beneficial low glycemic properties, after only 7 days, these pulse-based diets decrease macronutrient and amino acid digestibility. This is likely related at least in part to the lower animal protein content, but on a long-term basis could put domestic dogs at risk for low taurine and dilated cardiomyopathy.

Glycemic, insulinemic and methylglyoxal postprandial responses to starches alone or in whole diets in dogs versus cats: Relating the concept of glycemic index to metabolic responses and gene expression

Species differences between domestic cats (Felis catus) and dogs (Canis familiaris) has led to differences in their ability to digest, absorb and metabolize carbohydrates through poorly characterized mechanisms. The current study aimed to first examine biopsied small intestine, pancreas, liver and skeletal muscle from laboratory beagles and domestic cats for mRNA expression of key enzymes involved in starch digestion (amylase), glucose transport (sodium-dependent SGLTs and -independent glucose transporters, GLUT) and glucose metabolism (hexokinase and glucokinase). Cats had lower mRNA expression of most genes examined in almost all tissues compared to dogs (p < 0.05). Next, postprandial glucose, insulin, methylglyoxal (a toxic glucose metabolite) and d-lactate (metabolite of methylglyoxal) after single feedings of different starch sources were tested in fasted dogs and cats. After feeding pure glucose, peak postprandial blood glucose and methylglyoxal were surprisingly similar between dogs and cats, except cats had a longer time to peak and a greater area under the curve consistent with lower glycolytic enzyme expression. After feeding starches or whole diets to dogs, postprandial glycemic response, glycemic index, insulin, methylglyoxal and d-lactate followed reported glycemic index trends in humans. In contrast, cats showed very low to negligible postprandial glycemic responses and low insulin after feeding different starch sources, but not whole diets, with no relationship to methylglyoxal or d-lactate. Thus, the concept of glycemic index appears valid in dogs, but not cats. Differences in amylase, glucose transporters, and glycolytic enzymes are consistent with species differences in starch and glucose handling between cats and dogs.

Influence of type of starch and feeding management on glycaemic control in diabetic dogs

The present study evaluated the effects of two diets with different starch sources and two feeding methods on the glycaemic control in dogs with diabetes mellitus. The diets had similar nutrient contents (40% starch and 16% dietary fibre), one formulated with 46% of broken rice and the other with 42% sorghum and 10% lentils (as-fed). Ten client-owned diabetic dogs were fed with each diet for 2 months, in a crossover design. Five dogs received NPH human insulin and food every 12 h (feeding method 1), and the other five received insulin every 12 h but were fed three times a day (feeding method 2). In feeding method 2, morning insulin was higher than the evening dose and dogs received the second meal after 4 to 5 h of the morning insulin and meal. Parameters evaluated included insulin dosage, 12- and 8-h glycaemic curves, complete blood count, biochemical profile and urinalysis. Glycaemic curves were analysed by ANOVA with repeated measures. Glycaemic control parameters (fasting, mean, minimum and maximum glycaemia and serum fructosamine) and glucose area under the curve (AUC) were calculated and analysed by paired t test (p < 0.05). In feeding method 1, dogs fed the sorghum-based diet presented lower mean (p = 0.04) and minimum blood glucose concentrations (p = 0.03), and a tendency to lower maximum blood glucose (p = 0.06) and glucose AUC (p = 0.08) than when fed the rice-based diet. When food was provided twice a day, the ingestion of the rice-based diet resulted in higher post-prandial glucose response than the diet with sorghum and lentil. In feeding method 2, there was no effect of diet on the assessed parameters (p > 0.05). No differences in insulin dosage were observed between groups or feeding methods (p > 0.05). Providing two meals a day followed by insulin administration associated with the sorghum- and lentil-based diet improved glycaemic control in diabetic dogs.

A current review of structure, functional properties, and industrial applications of pulse starches for value-added utilization

Pulse crops have received growing attention from the agri-food sector because they can provide advantageous health benefits and offer a promising source of starch and protein. Pea, lentil, and faba bean are the three leading pulse crops utilized for extracting protein concentrate/isolate in food industry, which simultaneously generates a rising volume of pulse starch as a co-product. Pulse starch can be fractionated from seeds using dry and wet methods. Compared with most commercial starches, pea, lentil, and faba bean starches have relatively high amylose contents, longer amylopectin branch chains, and characteristic C-type polymorphic arrangement in the granules. The described molecular and granular structures of the pulse starches impart unique functional attributes, including high final viscosity during pasting, strong gelling property, and relatively low digestibility in a granular form. Starch isolated from wrinkled pea-a high-amylose mutant of this pulse crop-possesses an even higher amylose content and longer branch chains of amylopectin than smooth pea, lentil, and faba bean starches, which make the physicochemical properties and digestibility of the former distinctively different from those of common pulse starches. The special functional properties of pulse starches promote their applications in food, feed, bioplastic and other industrial products, which can be further expanded by modifying them through chemical, physical and/or enzymatic approaches. Future research directions to increase the fractionation efficiency, improve the physicochemical properties, and enhance the industrial utilization of pulse starches have also been proposed. The comprehensive information covered in this review will be beneficial for the pulse industry to develop effective strategies to generate value from pulse starch.

Glycemic response in nonracing sled dogs fed single starch ingredients and commercial extruded dog foods with different carbohydrate sources

This study adapted the established glycemic index (GI) methodology used in human research to perform two studies in sled dogs in order to assess the blood glucose-raising potential of pulse-based dog foods. The first was a pilot study (n = 6 dogs) to determine the GI of single starch sources (white bread, cooked white rice, and cooked green lentils) using a glucose solution as control. Next, the effect on glycemic and insulinemic meal responses and GI of commercial extruded dog foods containing different categories of starch sources (traditional grain, whole grain, grain-free, and vegan) were investigated on 11 dogs using a glucose control. Results were compared using repeated measures analysis of variance (ANOVA). Consumption of 10 g of available carbohydrate (Av CHO) was insufficient to elicit a measurable response in blood glucose for GI determination, and as such, the amount was increased to 25 g for the second study. The GI (±SE) of the single starch sources and dog foods was: white bread: 47 ± 11, cooked white rice: 71 ± 14, cooked green lentils: 60 ± 20 (P = 0.569), traditional grain: 83 ± 17, whole grain: 56 ± 8, grain-free: 41 ± 6, and vegan: 65 ± 15 (P = 0.154). No statistical differences in glycemic response over time were observed between the single starch sources or the extruded diets tested (P = 0.1412; P = 0.2651). The insulinemic response elicited by the extruded diets was also not different (P = 0.079); however, the traditional grain diet did have the slowest time to peak for insulin (P = 0.0078). Among single starch sources and extruded dog foods, there were no differences in the glycemic indices measured in this study. The GI methodology has not been validated for use in canine species, and it is likely that our results were due to higher interindividual variation or inadequate study power. Regardless, this study will serve to better define future studies to investigate the potential physiological benefits of low GI foods for dogs.

Compartmental fat distribution in the abdomen of dogs relative to overall body fat composition

Background

Adipose tissue may have different metabolic and endocrine functions depending on the region of the body in which it is located. While visceral or intra-abdominal fat has been found to contribute to leptin concentrations, insulin resistance and obesity-related diseases, there are only a few imaging studies documenting the preferential distribution of body fat to either the intra-abdominal or subcutaneous compartments in dogs. This study aimed to determine if CT-measured abdominal fat distributed preferentially to the visceral space (V) relative to the subcutaneous space (SQ), with increasing DXA-determined total body fat percentage; and if ultrasound measurements of the ventral midline subcutaneous (SAT) and visceral adipose thickness (VAT) can be used to estimate the distribution of fat to the subcutaneous and visceral abdominal spaces, in a sample of 22 dogs with variable body condition.

Results

Multivariate analysis showed no statistically significant correlation between visceral to subcutaneous fat ratio (V/SQ) and increasing total body fat percentage (β = − 0.07, p = 0.733), but strong correlation with age (β = 0.71 p = 0.002). A substantial amount of variation for the ultrasound visceral adipose thickness to subcutaneous fat thickness (VAT/SAT) could be explained by both CT V/SQ and sex (R²_Adjusted = 0.477, p = 0.001), with female dogs having significant lower VAT/SAT ratios compared to the male dogs (p = 0.047). The ultrasound fat measurements appeared moderately reliable, but a larger sample number is required to confirm this.

Conclusions

The findings suggest that dogs with a relatively healthy to slightly overweight body condition score, distribute fat relatively similarly between their peritoneal (visceral) and subcutaneous abdominal compartments with increasing total body fat percentage. However, there was increased fat distribution to the peritoneal space relative to the subcutaneous space with increasing age. Further, abdominal ultrasound may be useful in estimating the ratio of fat distribution to both the abdominal visceral and subcutaneous spaces.

Influence of macronutrient composition of commercial diets on circulating leptin and adiponectin concentrations in overweight dogs

Leptin and adiponectin play important roles in obesity‐related inflammation and comorbidities. Previous research suggests that alterations in dietary macronutrient composition can modify circulating leptin and adiponectin concentrations in people, but limited research on this subject has been performed in dogs. This study investigated the effects of commercial high protein (HP), high fat (HF) and high carbohydrate medium protein (HCMP) diets on baseline (T₋₁) concentrations, post‐prandial peak concentrations and total release in a ten‐hour time span of leptin and adiponectin in dogs, when compared to a maintenance high carbohydrate low protein (HCLP) diet. Thirty‐six overweight dogs were fed the HCLP diet in a one‐week control period, after which the animals were assigned to one of three groups. In three four‐week periods, each group was fed all test diets in a different sequence. At the last day of each period, blood was sampled at one hour before feeding (T₋₁) and at three (T₃), six (T₆) and nine (T₉) hours after feeding. Feeding caused peak leptin concentrations at T₆ and T₉ (p < .001). No significant post‐prandial change in adiponectin concentrations was found (p = .056). The HP diet resulted in lower leptin peak concentrations (p = .004) and AUC_T−1–T9 (p = .01), but none of the diets influenced baseline leptin concentrations (p = .273). Baseline adiponectin concentrations were lower for the HF diet (p = .018) and HCMP (p < .001), and the HP, HF and HCMP AUC_T−1–T9 (p < .001) were lower compared with the HCLP diet. Female dogs had lower adiponectin baseline concentrations (p = .041) and AUC_T−1–T9 (p = .023) than male dogs. In conclusion, the HP diet was associated with the lowest post‐prandial peak leptin concentration and the least decrease in adiponectin release, suggesting that a HP diet may improve immune‐metabolic health and post‐prandial satiety in overweight dogs.

Effects of pea with barley and less-processed maize on glycaemic control in diabetic dogs

The source of starch may interfere with glycaemic control in dogs, but few studies have evaluated these aspects in diabetic dogs. This study compared the effects of two isonutrient diets with different starch sources, peas and barley (PB) v. maize (Mi), on diabetic dogs. The Mi diet was processed in order to generate a lower starch gelatinisation index. In all, fifteen adult diabetic dogs without other conditions were included. The animals were fed two dry extruded rations with moderate levels of fat and starch and high levels of protein and fibre using a random, double-blind cross-over design. Glycaemic curves over 48 h were developed via continuous glucose monitoring after 60 d on each diet and with the same neutral protamine Hagedorn (NPH) insulin dosage. The following were compared: fasting, mean, maximum and minimum blood glucose, maximum and minimum glycaemia difference, glycaemic increment, area under the glycaemic curve, area under the glycaemic increment curve and serum fructosamine concentration. Paired t tests or Wilcoxon signed-rank tests were used to compare the amount of food and nutrients ingested and the dietary effects on glycaemic variables between the diets. Dogs fed the PB diet presented a lower average mean interstitial glucose (P=0·01), longer mean hypoglycaemic time (P<0·01), shorter mean hyperglycaemic time (P<0·01) and smaller difference between maximum and minimum blood glucose levels (P=0·03). Thus, the processing applied to the Mi diet was not sufficient to achieve the same effects of PB on glycaemic control in diabetic dogs.

Recovery of insulin sensitivity and optimal body composition after rapid weight loss in obese dogs fed a high-protein medium-carbohydrate diet

This study investigated the effects of an experimental high-protein medium-carbohydrate diet (protein level, 46% metabolizable energy, ME). First, postprandial plasma glucose and insulin kinetics were determined in steady-state overweight/obese Beagle dogs (28%-41% excess body weight) for an experimental high-protein medium-carbohydrate diet (protein level, 46% ME) and a commercial high-carbohydrate medium-protein diet (protein level, 24%ME) in obese dogs. Secondly, all the dogs were included in a weight loss programme. They were fed the high-protein medium-carbohydrate diet, and the energy allocation was gradually reduced until they reached their optimal body weight. Insulin sensitivity and body composition were evaluated before and after weight loss using a euglycaemic-hyperinsulinaemic clamp and the deuterium oxide dilution technique respectively. For statistical analysis, linear mixed effect models were used with a significance level of 5%. Postprandial plasma glucose and insulin concentrations were substantially lower with the high-protein medium-carbohydrate diet than the high-carbohydrate medium-protein diet. These differences can be explained mainly by the difference in carbohydrate content between the two diets. Energy restriction (35% lower energy intake than in the obese state) resulted in a 2.23 ± 0.05% loss in body weight/week, and the dogs reached their optimal body weight in 12-16 weeks. Weight loss was associated with a significant increase in insulin sensitivity. The high-protein medium-carbohydrate diet allowed fat-free mass preservation despite a relatively high rate of weekly weight loss. The increase in insulin sensitivity indicated improved control of carbohydrate metabolism, possible due to weight loss and to the nature of the diet. Thus, a high-protein medium-carbohydrate diet is a good nutritional solution for managing the weight of overweight dogs. This diet may improve glycaemic control, which could be beneficial for preventing or managing impaired glucose tolerance in obese dogs and for safe and successful weight loss while preserving lean body mass.