Components of fiber impair iron absorption in the dog

Dietary fiber aids in the management of canine and feline gastrointestinal disease

Dietary fiber describes a diverse assortment of nondigestible carbohydrates that play a vital role in the health of animals and maintenance of gastrointestinal tract homeostasis. The main roles dietary fiber play in the gastrointestinal tract include physically altering the digesta, modulating appetite and satiety, regulating digestion, and acting as a microbial energy source through fermentation. These functions can have widespread systemic effects. Fiber is a vital component of nearly all commercial canine and feline diets. Key features of fiber types, such as fermentability, solubility, and viscosity, have been shown to have clinical implications as well as health benefits in dogs and cats. Practitioners should know how to evaluate a diet for fiber content and the current knowledge on fiber supplementation as it relates to common enteropathies including acute diarrhea, chronic diarrhea, constipation, and hairball management. Understanding the fundamentals of dietary fiber allows the practicing clinician to use fiber optimally as a management modality.

Chemical composition and in vitro fermentation characteristics of ancient grains using canine fecal inoculum

Human interest in ancient grains replacing traditional carbohydrate sources has reached the pet food market; however, chemical composition of these grains and their digestive properties in the canine model, specifically the fermentative characteristics, have not been established. Five ancient grain varieties were analyzed: amaranth (AM), white proso millet (WPM), oat groats (OG), quinoa (QU), and red millet (RM). Cellulose (CEL) was used as a negative control, and beet pulp (BP) was used as a positive control. Substrates were analyzed for macronutrient composition as well as free and hydrolyzed sugar profiles in addition to their in vitro fermentative characteristics. Substrates were allocated into 2 sets to allow for quantification of pH, short-chain fatty acids, and branched-chain fatty acids, as well as gas volume and composition. Samples were digested for 6 and 18 h with pepsin and pancreatin, respectively, prior to inoculation with fecal bacteria for 0, 3, 6, 9, or 12 h. Detectable levels of cereal β-glucans were observed solely in OG (3.5%), with all other substrate containing <0.35% cereal β-glucans. All test substrates had fairly similar macronutrient and starch profiles with the exception of RM that contained the highest resistant starch content (2.4%), with all other test substrates containing <0.5% resistant starch. However, the analyzed pseudocereals, AM and QU, had the highest concentrations of free glucose while the minor cereal grains, WPM, OG, and RM, contained the highest concentrations of hydrolyzed glucose. All test substrates had propionate production values similar or greater than BP after 3, 6, 9, and 12 h of fermentation, and similar or greater butyrate production values than BP after 6, 9, and 12 h. All substrates had greater (P < 0.05) changes in pH than CEL after 6, 9, and 12 h, with AM, WPM, OG, and RM having greater (P < 0.05) changes in pH than BP after 9 and 12 h. These data suggest select ancient grains have similar fermentation characteristics as BP, a moderately fermentable fiber considered the gold standard in terms of fiber sources in the pet food market today, and that OG and AM may be more fermentable during longer fermentation periods.

[Effect of quinoa extract consumption on iron deficiency-induced anemia in mice]

OBJECTIVES

To determine the effect of quinoa extract consumption on iron deficiency-induced anemia in mice.

MATERIALS AND METHODS

Thirty male M. musculus albino mice of the Balb/c strain, with an average weight of 24±32.7 g, were used. Three groups of ten mice each were formed: 1) a negative control group of iron-sufficient (IS) mice that received 40g/d of balanced feed for 7 weeks; 2) a positive control group of iron-deficient (ID) mice that received 40g/d of feed rich in iron for 7 weeks; and 3) an experimental group of ID mice that received 40 g/d of feed rich in iron for 7 weeks and 20 g/d of quinoa extract (QE) from week 5. Hemoglobin levels were measured.

RESULTS

At the end of the treatment, a significant difference was found in hemoglobin levels between the positive (ID mice: 8.9±1.1 g/dL) and experimental (ID+QU mice: 11.4±0.5 g/dL) groups (student's t, p<0.05). No significant difference was found in hemoglobin levels at the end of the induction period between the positive (IS mice: 9.1±1.1) and experimental (ID mice: 9.3±0.7) groups (student's t, p>0.05).

CONCLUSIONS

Under experimental conditions, quinoa has an antianemic effect based on the results of hemoglobin levels.

Efecto del consumo del extracto de alfalfa (medicago sativa) en anemia ferropénica inducida, en ratones (mus musculus)

Objetivos Determinar el efecto del consumo del extracto de alfalfa en anemia ferropénica inducida, en ratones.Materiales y Métodos Se utilizaron treinta ratones albinos M. musculus de la cepa Balb/c, machos de peso promedio 23±33,7 g. Se formaron tres grupos de diez ratones cada uno: a) grupo control negativo hierro suficiente (HS), recibió 40g/d de alimento balanceado durante siete semanas; b) grupo control positivo hierro deficiente (HD), recibió 40g/d de dieta ferropénica durante siete semanas y; c) grupo experimental hierro deficiente (HD), recibió 40g/d de dieta ferropénica durante siete semanas y a partir de la semana cinco se agregó 20g/d de extracto de alfalfa (EA).Resultados Al finalizar el tratamiento se observó diferencia significativa en los niveles de hemoglobina entre los grupos control positivo (8.41±3.9 g/dL) y experimental (13.4±3.3 g/dL) (t student, p<0,05). No se encontró diferencia significativa en los niveles de hemoglobina, al término del periodo de inducción entre los grupos control positivo (8.76±3.9 g/dL) y experimental (8.59± 3.1 g/dL) (t student, p>0,05).Conclusiones En condiciones experimentales, la alfalfa presenta efecto antianémico, sustentado en los resultados de los niveles de hemoglobina.

Mineral absorption of diets containing natural carob fiber compared to cellulose, pectin and various combinations of these fibers Absorción de minerales de dietas que contienen fibra natural de algarrobas comparada con celulosa, pectina y varias combinaciones de estas fibras

The influence of the consumption of natural carob fiber (NCF), an insoluble hypocholesterolemic fiber, as the unique dietary fiber or combined with cellulose (CEL) or pectin (PEC), on mineral bioavailability was studied. Six groups of rats were fed for 10 days diets containing 10% CEL, NCF, PEC or CEL+NCF, CEL+PEC and NCF+PEC mixtures at 50%. Food intake was lower with PEC than NCF and CEL+NCF, but final body weight was unaffected. Fecal weight showed significant differ ences in the following order: CEL, NCF, CEL+NCF > CEL+PEC, NCF+PEC > PEC. Percentage of calcium absorption was higher with CEL+PEC and NCF+PEC compared with the rest of fibers. Mag nesium absorption was also significantly enhanced in these two groups compared to NCF (p < 0.0004). Iron absorption did not show variations. Zinc apparent absorption was reduced by PEC, but the NCF+PEC mixture counterbalanced this effect. Liver iron was significantly lower with NCF+PEC than CEL, and liver iron concentration was significantly lower with NCF+PEC compared to CEL+PEC. Liver zinc was significantly higher with CEL+NCF than PEC while liver zinc concentrations were slightly higher with the former (p = 0.05 compared to NCF). The results indicate that NCF, compared to CEL and PEC, did not decrease the efficiency of calcium, magnesium and iron absorption in rats, while compared to PEC it increased zinc apparent absorption. Moreover, by combining NCF with PEC calcium and magnesium, absorptions enhanced in comparison with NCF alone, which was prob ably a result of the combination of soluble and insoluble fibers.

Effect of phytic acid, tannic acid and pectin on fasting iron bioavailability both in the presence and absence of calcium

OBJECTIVE

To determine the effect of phytic acid, tannic acid and pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.

RESEARCH METHODS

Twenty-eight apparently healthy adult females participated in two iron absorption studies using radioactive iron isotopes ((59)Fe and (55)Fe). One group received 5mg of iron (as FeSO4) alone (control), together with 10mg of phytic acid, 100mg of tannic acid and 250mg of pectin (study A), on different days. The second group received the same iron doses and compounds as the other group, plus 800mg of calcium (CaCl2) (study B). The compounds were administered after an overnight fast, and no food or beverages were consumed for the following 3h. Iron status and circulating radioactivity were measured in venous blood samples.

RESULTS

The geometric means of iron bioavailability (range±1SD) for iron alone, iron with phytic acid, iron with tannic acid, and iron with citrus pectin were 25.0% (11.9-52.0); 18.9% (9.9-35.8); 16.8% (8.7-32.3); and 21.1% (10.2-43.9), respectively (repeated-measures ANOVA, p<0.02 (Dunnett's post hoc: control vs tannic acid p<0.05). When 800mg of calcium was added (study B), iron bioavailability was 16.7% (10.1-27.5); 13.2% (7.1-24.6); 14.8% (8.8-25.1); and 12.6% (5.5-28.8), respectively (repeated-measures ANOVA, NS).

CONCLUSIONS

Tannic acid decreases the fasting bioavailability of non-heme iron, however this effect did not exist in the presence of calcium. No effect was observed by phytic acid or citrus pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.

Nutrient and mineral composition during shoot growth in seven species of Phyllostachys and Pseudosasa bamboo consumed by giant panda

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 selection. Our objective was to examine the nutrient and mineral composition during three phases of shoot growth (<60, 90-150 and >180 cm) for seven species of bamboo (Phyllostachys (P.) aurea, P. aureosulcata, P. bissetii, P. glauca, P. nuda, P. rubromarginata, Pseudosasa japonica) fed to captive giant pandas at the Memphis Zoo. Total dietary fiber content of bamboo shoots increased (p < 0.0001) from an overall species average of 61% dry matter (DM) at < 60 cm to 75% DM at shoot heights > 180 cm, while crude protein, fat and ash exhibited significant declines (p < 0.05). Phyllostachys nuda had the overall greatest (p = 0.007) crude protein (21% DM) and fat (4% DM) content, and lowest overall total fibre (61% DM) content compared to the other species examined. In contrast, Pseudosasa japonica had the overall lowest crude protein and fat, and relatively higher fibre content (9%, 3% and 74% respectively). Concentrations of Zn and Fe were highest in shoots <60 cm (10-50 μg/g DM) and decreased (p < 0.05) during growth in all species examined. Concentrations of Ca, Cu, Mn, Na and K varied among species and were largely unaffected by growth stage. Due to their higher concentrations of nutrients and lower fibre content in comparison to culm and leaf, bamboo shoots should be a major component of captive giant panda diets when available.

Study of Ligmed-A, an antidiarrheal drug based on lignin, on rat small intestine enzyme activity and morphometry

This study aimed to determine the potential toxic effect of 4-day oral treatment with a lignin-based formulation on the enzymatic activity and morphology of the small intestine of rat. Ligmed-A is collected from sugarcane and is used to treat diarrhea in weaning pigs. The compound is about 90% lignin, an insoluble polyphenolic constituent of plants and a component of dietary fiber. The duodenal, jejunal and ileal mucosa of control rats and those receiving 2 g/kg Ligmed-A showed similar protein contents of about 100 mg/g. The sucrase and alkaline phosphatase activities of the three intestinal segments were unaltered after administration of the compound. Nonhistological alterations were observed after treatment. Our results, together with those of previous studies which found no toxicological effects, indicate that Ligmed-A could provide a potent antidiarrheal treatment in the veterinary area. However, further studies are required to examine its use in humans.

Iron bioavailability from diets containing isolated or intact sources of lignin

Experiments were conducted to determine effects of isolated lignin and intact lignin in foods on bioavailability of intrinsic iron in lignin-containing foods and of supplemental iron (FeSO4.H20). Standard curve and slope ratio methodology were employed to determine iron bioavailability to chicks. In one experiment, lignin content of foods ranged from 2 to 25% and iron bioavailability ranged from -20 to 140%, but no association between lignin content and bioavailability existed. In other experiments, increasing dietary lignin concentration from some natural sources reduced total iron availability, whereas increasing isolated lignin concentration had no effect. These results suggest that lignin structure or other unidentified factors determine intrinsic iron availability. No lignin source significantly decreased supplemental iron bioavailability.

Hemicellulose does not affect iron bioavailability in chicks

Two iron repletion experiments using hemoglobin as a response criterion were conducted to assess effects of hemicelluloses on iron bioavailability to chicks. In Experiment 1, iron bioavailability from intact fiber sources was determined by adding tomato pomace (14.6% hemicelluloses), soybean hulls (20.6% hemicelluloses), beet pulp (21.5% hemicelluloses), orchard grass (24.1% hemicelluloses) and corn fiber (55.2% hemicelluloses) to a casein dextrose basal diet providing 0.4-4.1% hemicelluloses to the diet. Test foods were analyzed for iron, total dietary fiber, neutral detergent residue, neutral detergent fiber, acid detergent fiber, acid detergent lignin, pectins and uronic acids. Hemicelluloses were determined by the difference of neutral detergent residue minus acid detergent fiber. Iron bioavailability was determined by the standard curve method to be (percent relative to ferrous sulfate using hemoglobin as the response criterion) as follows: tomato pomace, 82.0; soybean hulls, 94.0; beet pulp, 26.5; orchard grass, 68.9; corn fiber, 69.4. Iron bioavailability was not related to hemicellulose content of test foods or diets. In Experiment 2, the effect of psyllium husk (a fiber source that contains predominantly hemicelluloses) on iron bioavailability from ferrous sulfate was assessed. Bioavailability was determined by the slope ratio method where treatments consisted of graded levels of ferrous sulfate in the presence and absence of 5% dietary psyllium. Although iron intrinsic to psyllium was unavailable, bioavailability of ferrous sulfate iron was not affected (P > 0.05) by the presence of psyllium. Thus, there was no clear effect of hemicelluloses on iron bioavailability. However, some feeds that contained high levels of hemicelluloses had low intrinsic iron bioavailabilities, suggesting that other dietary factors are primarily responsible for determining iron bioavailability from these feed components.

Influence of intact and partially hydrolysed guar gum on iron utilization in rats fed on iron-deficient diets

Effects of partially hydrolysed guar gum (PHGG) or intact guar gum (GG) on iron utilization in rats fed on several iron-deficient diets were examined. Hemoglobin, serum iron and iron storage in liver of rats fed on iron-deficient diets as a control group (without PHGG and GG) significantly decreased, while those of the test group fed together with PHGG or GG were unchanged. In an iron balance test for 3 days, administration of PHGG or GG caused an increase in iron absorption. The results suggested that PHGG or its metabolites increase the bioavailability of dietary iron in deficiency.

Influence of type of diet and incubation time on in sacco release of Cu, Fe, Mn and Zn from Italian ryegrass, untreated and ammonia treated wheat straw

Artificially dried ryegrass, untreated and ammonia-treated wheat straw were ground and incubated in nylon bags in the rumen of three sheep each fed with diets based on roughage or concentrate. Dry matter degradability, the concentration and the release of the trace elements Cu, Fe, Mn and Zn from the incubated feeds were measured after 0 (washing loss), 6, 12, 24, 48 and 72 h rumen incubation time. Dry matter degradability, trace element concentration and their release were significantly influenced by the kind of incubated feeds, incubation time and feeding of sheep. Cu- (1.8-6.9 mg kg-1 DM) and Zn concentrations (36-103 mg kg-1 DM) of straw residues in the bags were much higher than those of original straw (1.2-1.6 and 8.1-9.9 mg kg-1 DM resp.). The inflow of Cu and Zn in the bags containing straw residues was higher than their release. The Cu-, Fe- and Mn-release from ryegrass was similar to the dry matter degradability, but the Zn-release was much lower.

Non-everted oxygenated rat intestinal segments as a measure of neutral detergent fiber effects on iron absorption

Iron absorption in the presence of varying amounts and sizes of dietary fiber was measured. A method using non-everted rat intestinal segments perfused in oxygen was refined. Neutral detergent fiber (NDF), a component of dietary fiber, was extracted from cooked pinto bean (Phaseolus vulgaris). The NDF did not affect iron absorption in intestinal segments from iron replete rats. However, 4 and 6 mg of NDF/ml significantly decreased iron absorption in the intestinal segments from anemic rats. NDF with a smaller particle size of 0.125 mm increased iron absorption relative to that absorbed with 0.180 mm particles. Histological examination validated using non-everted intestinal segments perfused with oxygen as a method for studying dietary effects on iron absorption. Segments which are not everted are less prone to damage. Perfusion with oxygen maintained metabolic activity in the tissue during the experiment.

Mineral retention in young men consuming soy-fiber-augmented liquid-formula diets

The effect of a nutritionally complete liquid-formula diet without soy polysaccharide or with the fiber source at 20, 30, or 40 g/d on mineral retention in young men was examined. Addition of 20 g soy polysaccharide to the liquid formula significantly (p less than 0.05) improved the retentions of copper, iron, zinc, and magnesium over the diet without added fiber. The highest level of soy polysaccharide (40 g/d) resulted in significantly (p less than 0.05) lower Cu, Zn, Fe, and Mg retentions than did the 20-g diet and the 30-g diet had an intermediate effect. Except for slightly negative Cu (-0.1 +/- 0.4 mg) and Fe (-0.6 +/- 3.7 mg) retentions on the 40-g diet, retentions of all minerals remained positive throughout this study. The liquid-formula diet supplemented with 40 g soy polysaccharide could have a deleterious effect on mineral retentions in persons consuming the diet as their sole nutritional source.

In vitro estimation of iron availability from a range of plant foods: influence of phytate, ascorbate and citrate

Plant foods were digested in vitro and the proportion of iron which diffused across a semi-permeable membrane was used as an index of Fe availability. The mean (with SEM) Fe diffusibility from a group of eighteen cereals, legumes and nuts was very low, 2.1 (0.25)%, whereas from a group of sixteen fruits and vegetables it was high, 31.7 (1.09)%. The difference between the two food groups was highly significant (P less than 0.001). The results for Fe diffusibility correlated well with literature values for the in vivo absorption of Fe from similar foods (r0.84, P less than 0.01). When phytate, citrate and ascorbate were added to selected foods in amounts corresponding to endogenous levels, only phytate and citrate gave the expected effects on Fe diffusibility. Ascorbate only enhanced Fe diffusibility to the expected extent when it was added in much larger amounts, not normally found in foods. When added to cereal foods, orange juice was found to enhance greatly Fe diffusibility even when its content of ascorbate was completely destroyed by boiling followed by prolonged storage. When citrate and ascorbate were added to cereal foods in amounts equivalent to those found in fresh orange juice, both enhanced Fe diffusibility but citrate was far more effective. It is concluded that phytate is a major inhibitor of Fe diffusibility in cereals, legumes and nuts. However, citrate rather than ascorbate would appear to be the major enhancer of Fe diffusibility from many fruits and vegetables. The implications of the present results are discussed in relation to the relative influence of phytate, citrate and ascorbate on dietary Fe availability.

Dietary fibre and mineral metabolism

Current dietary recommendations urge, inter alia, an increased consumption of fibre-containing foods. Some experimental studies made on various animals and man indicate that the associated increases in intakes of fibre and phytic acid may prejudice mineral status respecting calcium, magnesium, iron and zinc. An examination has been made of the experimental evidence, also of the epidemiological evidence on numerous types of populations, past and present, developing and developed. It has been concluded that diets high in fibre, characteristically do not have meaningful ill effects on well-being or unequivocally enhance morbidity. In particular populations in certain regions where deleterious effects have been reported it is judged that local factors, not wholly understood, are in operation. In assessing the extent of the benefit to be derived from the dietary changes urged, results must be viewed holistically and not in isolation. It is believed that the beneficial effects respecting reduced pronenesses to various degenerative diseases are likely to far outweigh the possible adverse effects of reduced bioavailability of mineral nutrients.

Dietary fibers and supplementary iron in a milk replacer for veal calves

Thirty 1-wk-old male Holstein calves were allotted randomly to six groups into a 3 X 2 factorial design. The control diet was skim milk, whey, tallow, vitamins, and minerals. Either Alpha-Floc or pectin was added at 5% dry matter. Supplementary iron was added at 30 and 50 ppm (dry basis). The six diets were fed for 14 wk. Calves without supplementary iron were mildly anemic at 6 wk and severely at 14 wk (7 and 5 g/dl hemoglobin). At 14 wk, both fibers had decreased blood hemoglobin in calves given supplementary iron. Feed refusal began at 8 wk with the appearance of anemia for calves unsupplemented with iron, but both Alpha-Floc and pectin decreased feed refusal. Supplementary iron practically eliminated feed refusal. Supplementary iron improved average daily gain and feed conversion, but dietary fibers had no effect. Adding Alpha-Floc and pectin to the diets reduced frequency of diarrheic feces. Mean carcass weight of calves fed supplementary iron was 11.6% higher than that of unsupplemented calves. Supplementary iron decreased liver lipids and increased glutamic oxaloacetic transaminase activity in blood plasma.