Effects Of Long-term Dietary Supplementation Research Articles

Effects of extended dietary supplementation with Santalum album essential oil on hemato-biochemical changes, innate immune response, antioxidant status, and expression of related gene in Nile tilapia (Oreochromis niloticus).

The effects of long-term dietary supplementation with sandalwood (Santalum album L.) essential oil (SEO) was investigated on hemato-biochemical biomarkers, immune status, antioxidant capacity, and resistance against Staphylococcus aureus in Nile tilapia (Oreochromis niloticus). Five groups (with four replicates) of O. niloticus (12.60 ± 0.20 g) were fed diets supplemented with SEO at doses of 0, 0.5, 1.0, 2.0, and 4.0 mL/kg diet for 60 days. Results indicated a substantial increase in blood protein levels and lower serum cholesterol, cortisol, glucose, urea, creatinine levels and, transaminase activities of fish fed a 2.0-mL SEO/kg diet. Serum lysozyme activity, nitric oxide, complement-3 levels, and phagocytic activity were significantly improved in O. niloticus after 60 days of feeding SEO-supplemented diets. Dietary SEO at level of 2.0-mL SEO/kg diet increased the activities of SOD, CAT, and GPx, and decreased MDA levels in liver homogenate. In addition, dietary 2.0-mL SEO/kg diet significantly upregulated antioxidant genes expression (CAT, SOD, GPx, GST, and GSR) with downregulation of apoptotic genes (HSP70, TLR2, caspase-3, and PCNA) in the liver. Furthermore, SEO-enriched diets significantly down-regulated pro-inflammatory (TNF-α, IL-1β, and IL-8) and up-regulated anti-inflammatory cytokine genes (TFG-β and IL-10) in the spleen. Moreover, SEO fortification increased the relative percentage of survival against S. aureus challenge and regulated immune-antioxidant genes in the spleen after the challenge. Overall, the results revealed that long-term using SEO might strengthen the physiological performance, hepatic oxidant/antioxidant balance, innate immune response, and resistance of O. niloticus against bacterial infections.

Preventive effects of a nutraceutical mixture of berberine, citrus and apple extracts on metabolic disturbances in Zucker fatty rats.

The prevention of obesity represents a major health and socio-economic challenge. Nutraceuticals are regularly highlighted for their beneficial effects in preventing the metabolic disturbances associated with obesity. However, few studies have described the combined action of nutraceutical mixtures combining polyphenols with alkaloids. The aim of this study was to evaluate the effects of long-term dietary supplementation with a mixture of Berberine, Citrus and Apple extracts (BCA) in the primary prevention of obesity and its metabolic and vascular complications in the obese Zucker rat, a spontaneous model of genetic obesity and insulin resistance. Sixteen 8-week-old obese Zucker male rats were randomly divided into two groups: all rats received oral gavage daily either with water, untreated obese (U-ObZ) or BCA (BCA-ObZ) mixture for thirteen weeks. Morphological and metabolic parameters were measured along the study. Cumulative concentration-response curves to insulin, acetylcholine and phenylephrine were determined on isolated thoracic aorta. Colon permeability measurements were performed using the Ussing chamber technique. Fecal samples collected at the beginning and the end of the protocol were used as a template for amplification of the V3-V4 region of the 16S rDNA genes. BCA supplementation reduced weight gain (p<0.05) and food intake (p<0.05) in the BCA-ObZ group rats compared to the U-ObZ group rats. It also improved glucose tolerance (p<0.001) and decreased fasting insulin and Homeostasis model assessment index (p<0.05). Through ex vivo experiments, the BCA mixture enhanced significantly aortic insulin relaxation (p<0.01), reduced α1-adrenoceptor-mediated vasoconstriction (p<0.01), and decreased distal colon permeability. Moreover, short-chain fatty acid producers such as Bacteroides, Blautia, and Akkermansia were found to be increased by the BCA mixture supplementation. The results showed that a 13-week-supplementation with BCA mixture prevented weight gain and improved glucose metabolism in obese Zucker rats. We also demonstrated that BCA supplementation improved vascular function, colonic barrier permeability and gut microbiota profile.

Effect of long-term dietary supplementation with lavender, Lavandula angustifolia, oil on European seabass growth performance, innate immunity, antioxidant status, and organ histomorphometry

Effect of long-term dietary supplementation with lavender, Lavandula angustifolia, oil on European seabass growth performance, innate immunity, antioxidant status, and organ histomorphometry

Effects of long-term dietary supplementation of fermented wheat bran on immune performance and inflammatory response in laying hens

ABSTRACT This study was conducted to investigate the effects of solid-state fermented wheat bran on immune performance and inflammatory response in laying hens. A total of 225 18-week-old Hy-Line brown-egg laying hens were randomly divided into 3 groups with 5 replicates per group and 15 hens per replicate. Laying hens were fed a basal diet (corn-soybean meal diet) supplemented with 0 (control group), 10% wheat bran and 10% fermented wheat bran, respectively. The results showed: (1) Compared to wheat bran group, the contents of crude protein, trichloroacetic acid-soluble protein, dietary fibre (DF), mannan and total polyphenols in wheat bran were increased by solid state fermentation. (2) Compared to the control group, fermented wheat bran increased the levels of serum biochemical parameters, reproductive hormones, immunoglobulins and anti-inflammatory factors. Therefore, long-term dietary supplementation of 10% fermented wheat bran plays an important role in improving the immune performance of laying hens.

Effects of paternal diet and antioxidant addition to the semen extender on bovine semen characteristics and on the phenotype of the resulting embryo

The aim of this study was to examine the effects of long-term dietary supplementation of young Nellore bulls with rumen-protected polyunsaturated fatty acids (PUFAs) and of the inclusion of catalase in the semen extender on semen quality, in vitro sperm fertilizing ability, and intracytoplasmic lipid content in the resulting embryos. Twelve Nellore bulls were supplemented with rumen-protected PUFAs or with a basal diet from 14 to 24 months of age. The semen was collected at the end of supplementation. For cryopreservation, the ejaculate was divided into two equal volumes and catalase was added to the extender in one of the fractions. Thus, the experimental design consisted of a 2 × 2 factorial scheme with two diets (control and PUFA) and two extenders (Cat+ and Cat-). Total motility and the percentage of rapid cells in fresh semen were negatively affected by dietary supplementation with PUFAs (P < 0.05), but these effects did not persist after freezing. The frozen/thawed semen of animals fed PUFAs exhibited an increase in the percentages of damaged plasma and acrosomal membranes, as well as an increase in the proportion of lipids ions at m/z 578 and m/z 757 detected by MALDI-MS. Nevertheless, there was no effect of the treatments on in vitro embryo development. However, embryos derived from bulls supplemented with PUFAs exhibited higher lipid accumulation compared to control (P < 0.05). In conclusion, PUFA supplementation promoted worsening of semen quality without affecting the in vitro sperm fertilizing ability; however, the paternal diet affected the intracytoplasmic lipid content in the resulting embryos.

Long-Term Effects of Dietary Supplementation with Olive Oil and Hydrogenated Vegetable Oil on the Rumen Microbiome of Dairy Cows

Dietary lipids increase energy density in dairy cow diets and in some cases can increase beneficial fatty acids (FA) in milk and dairy products. However, the degree of FA saturation may affect the rumen microbiome. The objective of this study was to determine the long-term effects of feeding saturated (hydrogenated vegetable oil; HVO) or unsaturated (olive oil; OO) fatty acid (FA) sources on the rumen microbiome of dairy cows. For 63 days, 15 mid-lactating cows were fed with either a basal diet (no fat supplement), or the basal diet supplemented with 3% dry matter (DM), either HVO or OO. Rumen contents were collected on days 21, 42 and 63 for 16S rRNA gene sequencing using the Illumina MiSeq platform. The results reveal dominance of the phyla Firmicutes (71.5%) and Bacteroidetes (26.2%), and their respective prevalent genera Succiniclasticum (19.4%) and Prevotella (16.6%). Succiniclasticum increased with both treatments at all time points. Prevotella was reduced on day 42 in both diets. Bacterial diversity alpha or beta were not affected by diets. Predicted bacterial functions by CowPI showed changes in energy and protein metabolism. Overall, 3% DM of lipid supplementation over 63 days can be used in dairy cow diets without major impacts on global bacterial community structure.

Long-Term Effects of Dietary Supplementation with Olive Oil and Hydrogenated Vegetable Oil on the Rumen Microbiome of Dairy Cows

Long-Term Effects of Dietary Supplementation with Olive Oil and Hydrogenated Vegetable Oil on the Rumen Microbiome of Dairy Cows

Long-Term Effects of Dietary Supplementation with Olive Oil and Hydrogenated Vegetable Oil on the Rumen Microbiome of Dairy Cows

Long-Term Effects of Dietary Supplementation with Olive Oil and Hydrogenated Vegetable Oil on the Rumen Microbiome of Dairy Cows

Short- and long-term probiotic effects of Enterococcus hirae isolated from fermented vegetable wastes on the growth, immune responses, and disease resistance of hybrid catfish (Clarias gariepinus × Clarias macrocephalus)

This study evaluated the short- and long-term effects of dietary supplementation with Enterococcus hirae strain UPM02 on the growth performance, immunity, and disease resistance of hybrid catfish (Clarias gariepinus × Clarias macrocephalus) against Aeromonas hydrophila infection. In the long-term trial, fingerling fish were fed diets containing 0 (control), 2 × 105, or 2 × 107 CFU/g E. hirae UPM02 for 120 days. Administration of E. hirae UPM02 had significant effects on the specific growth rate (SGR), feed utilization efficiency, body indices (P < 0.05), and gut villus physiology of the catfish. E. hirae UPM02 application also significantly increased the complete blood cell counts, phagocytic activity, respiratory burst, lysozyme activity, and alternative complement pathway hemolytic (ACH50) activity in tested catfish throughout the experimental periods (P < 0.05). Dietary E. hirae UPM02 at both concentrations significantly increased the expression levels of the alpha-2-macroglobulin (α2M), CC chemokines, CXC chemokines, lysozyme c (LYZC), myeloperoxidase (MYE), NF-kappa-B1 p105 subunit (NF–K), and bactericidal permeability-increasing protein (BPIP) genes in the head kidney, liver, and spleen (P < 0.05) at days 80, 100 and 120 after application. However, heat shock protein 70 (HSP70) gene expression was slightly downregulated in these organs. Interestingly, fish fed the diets containing 2 × 105 and 2 × 107 CFU/g E. hirae UPM02 exhibited a significantly lower (P < 0.05) postchallenge mortality rates (32% and 30%, respectively) after 14 days of A. hydrophila challenge than the control fish (58%). In short-term (28 days) application to juvenile catfish, the two concentrations of E. hirae did not affect all growth parameters. Nevertheless, these concentrations markedly elevated all tested immune parameters, similarly to long-term application. Immune-related gene expression was significantly upregulated at day 28 in the head kidney, at day 14 in the liver, and at day 7 in the spleen in fish treated with the two concentrations of the probiotics (P < 0.05). Mortality at 14 days after challenge with A. hydrophila in the groups receiving the two concentrations of the probiotic was significantly lower than that in the control group, at 28, 24, and 48%, respectively (P < 0.05). These results collectively suggest that dietary supplementation with E. hirae UPM02 at 2 × 105 and 2 × 107 CFU/g effectively influenced immune responses, enhanced disease protection, and stimulated immunity-related gene expression in hybrid catfish under both short- and long-term application. However, growth enhancement was significantly evidenced with long-term application only.

Chemopreventive effects of nanoparticle curcumin in a mouse model of Pten-deficient prostate cancer.

The present study investigated the antitumor activity and chemopreventive effects of a nanoparticle formulation of curcumin in preclinical models of mousePten-deficientprostate cancer. The antitumor activity of the nanoparticle curcumin was evaluated in mouse castration-naïve (7113-D3) and castration-resistant prostate cancer (2945-E10) derived cell lines in vitro. Cell viability was reduced in both cell lines in a dose and time-dependent manner. The effects of long-term dietary supplementation with the nanoparticle curcumin formulation were evaluated in a conditional Pten-deficient mouse model. Prostate tissues from Pten-deficient prostate cancers were obtained after sixteen weeks of dietary supplementation of 76mg/kg/day or 380mg/kg/day nanoparticle curcumin. Daily supplementation of nanoparticle curcumin did not affect mouse bodyweights or spleen size but did result in enlargement of the liver. Dietary supplementation did not influence tumor burden, however, mice fed high-dose curcumin had lower cancer cell proliferation rates at 12 and 16weeks of age. Together, these results show that daily supplementation of a nanoparticle formulation of curcumin is tolerable and suggest that curcumin could have chemopreventive activity in early-stage prostate cancer.

Long term dietary supplementation with microalgae increases plasma docosahexaenoic acid in milk and plasma but does not affect plasma 13,14-dihydro-15-keto PGF2α concentration in dairy cows.

The aims of the study were to determine the long-term effects of dietary supplementation with microalgae (SCIM) on milk and blood fatty acid (FA) composition and reproductive hormones in early lactation dairy cows. Sixty Holstein-Friesian dairy cows (30 per treatment) were unsupplemented (Control) or supplemented with 100 g of SCIM (Schizochytrium limacinum sp.) per cow per day from 25 ± 0.5 d post-partum for 98 d. Intake and milk yield were recorded daily, with milk samples collected at weeks 0, 1, 2, 4, 8 and 14, and blood samples collected from 12 representative pairs per treatment at weeks 0, 2, 4, 8, and 14 for subsequent analysis of FA, β-hydroxybutyrate, non-esterified fatty acids and glucose. At 33 ± 0.9 d postpartum the oestrus cycle of 24 cows (12 per treatment) were synchronized and plasma 13,14-dihydro-15-keto PGF2α (PGFM) concentrations determined following an oxytocin challenge. Data were analysed by repeated measures analysis of variance. There was no effect of treatment on dry matter intake, milk yield or milk fat content, with mean values across treatments of 22.1 and 40.6, and 37.2 g/kg respectively. Milk fat concentration of C22:6 n-3 increased rapidly in cows receiving SCIM, reaching a maximum of 0.38 g/100 g FA by week 14. Similarly, blood concentration of C22:6 n-3 increased to 1.6 g/100 g FA by week 14 in cows fed SCIM. There was no effect of treatment on plasma metabolites, but plasma glucose was lower in cows fed SCIM compared to the Control at week 2, and higher in week 8. There was no effect of treatment on peak plasma PGFM concentration or area under the curve. It is concluded that feeding SCIM rapidly increases blood and milk concentrations of C22:6 n-3 which are maintained over time, but does not improve plasma PGFM in dairy cows.

Effects of long-term supplementation with amino acid-complexed manganese on performance, egg quality, blood biochemistry and organ histopathology in laying hens

The current study was conducted to evaluate the effects of long-term dietary supplementation of amino acid-complexed manganese (Mn) on production performance, egg quality, blood biochemistry and organ histopathology in laying hens. A total of 756 Hy-Line Brown layers were randomly assigned into 7 dietary groups with 6 replicates. Each replicate contained 18 birds. Layers were fed a basal diet (Mn, 21.95 mg/kg) or the basal diet supplemented with 20, 40, 80, 120, 400 or 800 mg/kg Mn in amino acid-complexed form, respectively. The feeding trial lasted for 24 wks. Compared with the basal diet (control), dietary supplementation with 80 mg/kg Mn increased egg production and decreased feed conversion ratio (FCR) during 1–12 and 1–24 wk (P < 0.05). Manganese supplementation at 40 mg/kg increased egg production (1–12, 13–24 and 1–24 wk), egg mass (13–24 and 1–24 wk), and decreased FCR (13–24 and 1–24 wk, P < 0.05). Higher values of eggshell breaking strength were observed in dietary Mn addition ≥20 mg/kg treatments (P < 0.05) at different sampling time points, and they occurred in 40 mg/kg more frequently than any other Mn supplementation level. Dietary supplementation of 40 or 80 mg/kg Mn increased total superoxide dismutase (T-SOD) activity in serum (P < 0.05), but this benefit diminished when the inclusion exceeded 120 mg/kg. Besides, higher values of white blood cell (WBC), platelet and creatinine occurred in 400 and 800 mg/kg Mn addition groups (P < 0.05), accompanied with local inflammation of kidney tissues. In conclusion, dietary supplementation with Mn can improve productive performance, eggshell breaking strength and redox status, at a level of 40 mg/kg from Mn-amino acid complexes, and overdose of Mn supplementation (≥ 400 mg/kg) would cause detrimental effects to Hy-Line Brown laying hens.

Dietary supplementation with evodiamine prevents obesity and improves insulin resistance in ageing mice

Evodiamine is a major alkaloid extracted from the fruit of Evodia fructus, which reduces diet-induced obesity in young animals. We investigated the effects of long-term dietary supplementation with evodiamine on obesity, insulin resistance and longevity in normal ageing mice. Twelve-month-old C57BL/6J male mice were fed with standard chow with or without 1 or 10 mg evodiamine per kg food and maintained until death. Supplementation with low dose evodiamine prevented body weight gain and improved glucose tolerance in the mice, in which increased AMPK phosphorylation and down-regulation of mTOR signalling responsible for regulating energy metabolism were detected in white adipose tissue. However, evodiamine supplementation did not increase lifespan, and the high dose evodiamine caused excessive reduction in body weight, which could have side effects in aged animals. Thus, evodiamine at a low dose (1 mg/kg food) prevents obesity and insulin resistance even when ingestion begins in middle age.

Effect of dietary supplementation of rutin on lactation performance, ruminal fermentation and metabolism in dairy cows.

The effect of long-term dietary supplementation with rutin on the lactation performance, ruminal fermentation and metabolism of dairy cows were investigated in this study. Twenty multiparous Chinese Holstein cows were randomly divided into four groups, and each was offered a basal diet supplemented with 0, 1.5, 3.0 or 4.5 mg rutin/kg of diet. The milk yield of the cows receiving 3.0 and 4.5 mg rutin/kg was higher than that of the control group, and the milk yield was increased by 10.06% and 3.37% (p < 0.05). On the basis of that finding, the cows supplemented with 0 or 3.0 mg rutin/kg of diet were used to investigate the effect of rutin supplementation on blood metabolites and hormone levels. Compared with the control group, the serum blood urea nitrogen (BUN) concentration of the 3.0 mg rutin/kg group is significantly decreased (p < 0.05). In another trial, four adult cows with permanent rumen fistula and duodenal cannulae were attributed in a self-control design to investigate the peak occurrence of rutin and quercetin in different parts of the gastrointestinal tract, ruminal fermentation and microbial population in dairy cows. The cows supplemented with 3.0 mg rutin/kg in the diet differed from the control period. Samples of rumen fluid, duodenal fluid and blood were collected at 1, 2, 3, 4, 5, 6, 7 and 8 h after morning feeding. Compared to the control group, the pH, ammonia nitrogen concentration, number and protein content of rumen protozoa and blood urea nitrogen were lower, but the concentration of total volatile fatty acid (TVFA), microbial crude protein (MCP) and serum lysozyme content were higher for the cows fed the rutin diets. The addition of 3.0 mg rutin/kg to diets for a long term tended to increase the milk yield and improve the metabolism and digestibility of the dairy cows.

Effects of long-term dietary supplementation with conjugated linoleic acid on bovine oocyte lipid profile.

Nutritional and environmental conditions around conception and during early embryonic development may have significant effects on health and well-being in adult life. Here, a bovine heifer model was used to investigate the effects of rumen-protected fat supplementation on oocyte quality and embryo development. Holstein-Friesian heifers (n=84) received a dietary supplement consisting of rumen-protected conjugated linoleic acid (CLA) or stearic acid (SA), each on top of an isocaloric basic diet. Oocytes were collected via ultrasound-guided follicular aspiration and subjected to in vitro maturation followed by either desorption electrospray ionisation mass spectrometry (DESI-MS) for lipid profiling of individual oocytes or in vitro fertilisation and embryo culture. The type of supplement significantly affected lipid profiles of in vitro-matured oocytes. Palmitic acid and plasmalogen species were more abundant in the mass spectra of in vitro-matured oocytes after rumen-protected SA supplementation when compared with those collected from animals supplemented with CLA. Lipid concentrations in blood and follicular fluid were significantly affected by both supplements. Results show that rumen-protected fatty-acid supplementation affects oocyte lipid content and may pave the way for the establishment of a large-animal model for studies towards a better understanding of reproductive disorders associated with nutritional impairments.

Long-term effects of dietary supplementation with an essential oil mixture on the growth and laying performance of two layer strains

One thousand two hundred 1-day-old Lohmann LSL white and Lohmann Brown layer chickens were fed diets supplemented with either an antibiotic growth promoter (AGP) or an herbal essential oil mixture (EOM) till 58 wk of age to reveal the long-term effects of those additives on growth, performance and wholesome egg quality parameters. The study was arranged in a 2×3 factorial design with two layer strains and three feed additive regimens. Thus, the layer birds of both strains were randomly assigned to the three dietary treatments, i.e., standard basal diet (control), control with AGP (specifically, avilamycin, 10 mg/kg diet) and control with EOM (24 mg/kg diet). The data regarding egg production were recorded between 22 to 58 weeks of age. Neither the dietary treatments nor the bird strain influenced the body weight and mortality of the birds in both the growing and laying period. AGP or EOM supplementation to the laying hen diet significantly increased the egg production rate and egg weight as compared to the control diet alone, but egg mass output, feed consumption, and feed conversion ratio were not affected by the dietary treatments. Neither dietary treatment created any statistically significantly differences in egg quality parameters. The research findings have confirmed the beneficial effects of supplementation with feed-grade EOM on the laying rate and egg weight of both white and brown layers. Indeed, EOM, being a novel feed additive natural origin, proved to be as efficacious as AGP in promoting egg yield.

Fish oil diets alter the phospholipid balance, fatty acid composition, and steroid hormone concentrations in testes of adult pigs

The objective was to determine the effect of long-term dietary supplementation of two types of fish oil on lipid composition and steroidogenesis in adult pig testis. Twenty-four Duroc boars, aged 204.5 ± 9.4 d (body weight 128.1 ± 16.7 kg) received daily 2.5 kg of an iso-caloric basal diet supplemented with: 1) 62 g of hydrogenated animal fat (AF); 2) 60 g of menhaden oil (MO) containing 16% of eicosapentaenoic acid (EPA) and 18% of docosahexaenoic acid (DHA); or 3) 60 g of tuna oil (TO) containing 7% of EPA and 33% of DHA. After these diets were consumed for 7 mo, testicular hormones, phospholipid content, and fatty acid composition of individual phospholipids in testis were determined. Body and reproductive organ weights were not significantly affected by dietary treatments. Testicular tissue from boars fed a TO diet, followed by those receiving MO and AF diets, had the lowest level of phosphatidylethanolamine (TO < MO < AF; P < 0.01) but the highest sphingomyelin (TO > MO > AF; P < 0.01). For each phospholipid, boars fed either the MO or TO diet had increased total omega-3 fatty acids, particularly DHA (P < 0.01), by reciprocal replacement of total omega-6 fatty acids (20:4n-6, 22:5n-6). The MO diet increased EPA more than the other diets. Testicular concentrations of testosterone and estradiol were lower in boars fed a TO diet than a MO diet (P < 0.02). In conclusion, long-term dietary supplementation of fish oil, regardless of the EPA/DHA ratio, modified the fatty acid compositions in testis and affected steroid production of healthy adult boars, which may represent a promising models for future studies on fertility.

Natural Antioxidants and Oxidative Stress Markers in Hemodialysis Patients

Renal failure is accompanied by oxidative stress. An optimum intake of antioxidants is thought to be important to protect against oxidative damage. This study looked at the effects of dietary supplementation on antioxidant status and lipid peroxidation in hemodialysis patients. During the study period, 34 patients who were undergoing regular hemodialysis consumed a fruit and vegetable diet. The effect of dietary supplementation was assessed by measurement of blood enzymatic and non-enzymatic antioxidant status and malondialdehyde (MDA) levels, before and after intervention. A significant increase in the levels of vitamins A and C, and superoxide dismutase activity was observed after 8 weeks of supplementation ( p < 0.001), whereas no significant variation was found in the levels of vitamin E and MDA ( p > 0.05). The findings indicate that low intake of antioxidant vitamins in the short term improves the levels of vitamins A and C as well as superoxide dismutase activity, but MDA level as a marker of lipid peroxidation does not change significantly. The effects of long-term dietary supplementation on oxidant/antioxidant levels in hemodialysis patients remain to be clarified.

The α-glucosidase inhibitor miglitol delays the development of diabetes and dysfunctional insulin secretion in pancreatic β-cells in OLETF rats

The Otsuka Long–Evans Tokushima Fatty (OLETF) rat, an animal model of type 2 diabetes, exhibits obesity, hyperglycemia and hyperlipidemia, with late onset of chronic and slowly progressive hyperinsulinemia. In this study, we examined effects of long-term dietary supplementation with the α-glucosidase inhibitor miglitol on the development of diabetes and the reduction of β-cells in the pancreas of OLETF rats. The OLETF rats were fed a control diet or a diet containing 800 ppm miglitol (miglitol diet) for 65 weeks from pre-onset stage (5 weeks old). The non-fasting blood glucose concentrations gradually increased in OLETF rats fed the control diet and, at week 64, were significantly higher than those in OLETF rats fed the miglitol diet and age-matched Long–Evans Tokushima Otsuka (LETO) rats, which are control, non-diabetic, non-obese rats of the same strain. Oral glucose tolerance tests revealed that OLETF rats fed the control diet showed pronounced impaired glucose tolerance, but those fed the miglitol diet did not. Furthermore, insulin concentrations after glucose-loading were significantly lower in OLETF rats fed the control diet than in those fed the miglitol diet. The islets of 65-week-old OLETF rats fed the control diet showed significant fibrosis and loss of β-cells, while those of age-matched control LETO rats had a normal appearance. Feeding OLETF rats a miglitol diet reduced fibrosis and the loss of β-cells. Our results suggest that dietary supplementation with miglitol from pre-onset stage in OLETF rats delays the onset and development of diabetes and preserves the insulin secretory function of pancreatic islets.

Fish oil diets do not improve insulin sensitivity and secretion in healthy adult male pigs

The effects of long-term dietary supplementation of fish oil (n-3 PUFA-rich) in adult male pigs on body condition as well as insulin sensitivity and secretion were examined. Fifteen Duroc boars aged 204.5 (sd 9.4) d (body weight 145.8 (sd 16.8) kg) received daily 2.5 kg basal diet with a supplement of: (1) 62 g hydrogenated animal fat (n 5); (2) 60 g menhaden oil containing 10.8 g DHA and 9.0 g EPA (n 6); (3) 60 g tuna oil containing 19.8 g DHA and 3.9 g EPA (n 4). Rations were balanced to be isoenergetic. After 7 months of treatments, oral glucose and meal tolerance tests were conducted after insertion of a catheter into the jugular vein. Dietary supplementation with n-3 PUFA altered the blood plasma profile: DHA and EPA increased whereas arachidonic acid decreased (P < 0.01). Plasma glucose, insulin and C-peptide responses to oral glucose and the test meal were not affected by treatments (P>0.34). For all animals, total body fat estimated from body weight and back fat thickness was correlated with both beta-cell function (by homeostasis model assessment (HOMA); r+0.63) and insulin sensitivity (index of whole-body insulin sensitivity and by HOMA; r - 0.63 and r+0.66, respectively). In conclusion, long-term supplementation with dietary n-3 PUFA did not affect insulin metabolism in healthy adult male pigs. The relationship between body fat and insulin sensitivity, well documented in human subjects, suggests that the adult male pig could be a promising animal model for studies on insulin metabolism.