Dietary lutein stimulates immune response in the canine

A Randomized Controlled Trial to Evaluate the Impact of a Novel Probiotic and Nutraceutical Supplement on Pruritic Dermatitis and the Gut Microbiota in Privately Owned Dogs

Pruritic dermatitis (PD) is a common presentation of canine allergic skin diseases, with diversity in severity and treatment response due to complex etiopathogenesis. Evidence suggests the gut microbiota (GM) may contribute to the development of canine allergies. A 10-week double-blind randomized controlled trial evaluated a novel probiotic and nutraceutical blend (PNB) on clinical signs of skin allergy, health measures, and the GM of privately owned self-reported pruritic dogs. A total of 105 dogs were enrolled, with 62 included in pruritus and health analysis and 50 in microbiome analysis. The PNB supported greater improvement of owner-assessed clinical signs of PD at week 2 than the placebo (PBO). More dogs that received the PNB shifted to normal pruritus (digital PVAS10-N: <2) by week 4, compared to week 7 for the PBO. While a placebo effect was identified, clinical differences were supported by changes in the GM. The PNB enriched three probiotic bacteria and reduced abundances of species associated with negative effects. The PBO group demonstrated increased abundances of pathogenic species and reduced abundances of several beneficial species. This trial supports the potential of the PNB as a supplemental intervention in the treatment of PD; however, further investigation is warranted, with stricter diagnostic criteria, disease biomarkers and direct veterinary examination.

Effects of a mildly cooked human-grade dog diet on gene expression, skin and coat health measures, and fecal microbiota of healthy adult dogs

Purported benefits of human-grade pet foods include reduced inflammation, enhanced coat quality, and improved gut health, but research is scarce. Therefore, we compared gene expression, skin and coat health measures, and the fecal microbiome of dogs consuming a mildly cooked human-grade or extruded kibble diet. Twenty beagles (BW = 10.25 ± 0.82 kg; age = 3.85 ± 1.84 yr) were used in a completely randomized design. Test diets included: 1) chicken and brown rice recipe [feed-grade; extruded; blue buffalo (BB)]; and 2) chicken and white rice [human-grade; mildly cooked; Just Food for Dogs (JFFD)]. The study consisted of a 4-week baseline when all dogs ate BB, and a 12-week treatment phase when dogs were randomized to either diet (n = 10/group). After the baseline and treatment phases, fresh fecal samples were scored and collected for pH, dry matter (DM), and microbiome analysis; blood samples were collected for gene expression analysis; hair samples were microscopically imaged; and skin was analyzed for delayed-type hypersensitivity (DTH), sebum concentration, hydration status, and transepidermal water loss (TEWL). Data were analyzed as a change from baseline (CFB) using the Mixed Models procedure of SAS (version 9.4). At baseline, fecal pH was higher (P < 0.05) and hair surface score, superoxide dismutase (SOD) expression, and tumor necrosis factor-α (TNF-α) expression was lower (P < 0.05) in dogs allotted to JFFD. The decrease in CFB fecal pH and DM was greater (P < 0.05) in dogs fed JFFD, but fecal scores were not different. The increase in CFB hair surface score was higher (P < 0.05) in dogs fed JFFD. The decrease in CFB TEWL (back region) was greater (P < 0.05) in dogs fed JFFD, but TEWL (inguinal and ear regions), hydration status, and sebum concentrations in all regions were not different. Hair cortex scores and DTH responses were not affected by diet. The increase in CFB gene expression of SOD, COX-2, and TNF-α was greater (P < 0.05) in dogs fed JFFD. PCoA plots based on Bray-Curtis distances of bacterial genera and species showed small shifts over time in dogs fed BB, but dramatic shifts in those fed JFFD. JFFD increased (adj. P < 0.05) relative abundances of 4 bacterial genera, 11 bacterial species, 68 KEGG pathways, and 167 MetaCyc pathways, and decreased (adj. P < 0.05) 16 genera, 25 species, 98 KEGG pathways, and 87 MetaCyc pathways. In conclusion, the JFFD diet dramatically shifted the fecal microbiome but had minor effects on skin and coat measures and gene expression.

Effects of a Saccharomyces cerevisiae fermentation product-supplemented diet on circulating immune cells and oxidative stress markers of dogs

Feeding Saccharomyces cerevisiae fermentation product (SCFP) has previously altered fecal microbiota, fecal metabolites, and immune function of adult dogs. The objective of this study was to investigate measures of skin and coat health, changes in circulating immune cell numbers and activity, antioxidant status, and oxidative stress marker concentrations of healthy adult dogs fed a SCFP-supplemented extruded diet. Sixteen adult English Pointer dogs (8 M, 8 F; mean age = 6.7 ± 2.1 yr; mean BW = 25.9 ± 4.5 kg) were used in a randomized crossover design study. All dogs were fed a control diet for 4 wk, then randomly assigned to either the control or SCFP-supplemented diet (0.13% of active SCFP) and fed to maintain BW for 10 wk. A 6-wk washout preceded the second 10-wk experimental period with dogs receiving opposite treatments. After baseline/washout and treatment phases, skin and coat were scored, and pre and postprandial blood samples were collected. Transepidermal water loss (TEWL), hydration status, and sebum concentrations were measured (back, inguinal, ear) using external probes. Oxidative stress and immune cell function were measured by ELISA, circulating immune cell percentages were analyzed by flow cytometry, and mRNA expression of oxidative stress genes was analyzed by RT-PCR. Change from baseline data was analyzed using the Mixed Models procedure of SAS 9.4. Sebum concentration changes tended to be higher (P < 0.10; inguinal, ear) in SCFP-fed dogs than in controls. TEWL change was lower (P < 0.05) on the back of controls, but lower (P = 0.054) on the ear of SCFP-fed dogs. Delayed-type hypersensitivity response was affected by diet and time post-inoculation. Other skin and coat measures and scores were not affected by diet. Changes in unstimulated lymphocytes and stimulated IFN-γ secreting T cells were lower (P < 0.05) in SCFP-fed dogs, while changes in stimulated T cells were lower (P < 0.05) in control-fed dogs. Upon stimulation, the percentage of cytotoxic T cells delta trended lower (P < 0.10) in SCFP-fed dogs. Change in serum superoxide dismutase concentrations was higher (P < 0.05) and change in catalase mRNA expression was lower (P < 0.05) in SCFP-fed dogs. All other measurements of immune cell populations, oxidative stress markers, and gene expression were unaffected by treatment. In conclusion, our data suggest that SCFP positively impacts indicators of skin and coat health of dogs, modulates immune responses, and enhances some antioxidant defense markers.

Carotenoids: Therapeutic Strategy in the Battle against Viral Emerging Diseases, COVID-19: An Overview

Carotenoids, a group of phytochemicals, are naturally found in the Plant kingdom, particularly in fruits, vegetables, and algae. There are more than 600 types of carotenoids, some of which are thought to prevent disease, mainly through their antioxidant properties. Carotenoids exhibit several biological and pharmaceutical benefits, such as anti-inflammatory, anti-cancer, and immunity booster properties, particularly as some carotenoids can be converted into vitamin A in the body. However, humans cannot synthesize carotenoids and need to obtain them from their diets or via supplementation. The emerging zoonotic virus severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), originated in bats, and was transmitted to humans. COVID-19 continues to cause devastating international health problems worldwide. Therefore, natural preventive therapeutic strategies from bioactive compounds, such as carotenoids, should be appraised for strengthening physiological functions against emerging viruses. This review summarizes the most important carotenoids for human health and enhancing immunity, and their potential role in COVID-19 and its related symptoms. In conclusion, promising roles of carotenoids as treatments against emerging disease and related symptoms are highlighted, most of which have been heavily premeditated in studies conducted on several viral infections, including COVID-19. Further in vitro and in vivo research is required before carotenoids can be considered as potent drugs against such emerging diseases.

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.

Heterogeneity of gut microbial responses in healthy household dogs transitioning from an extruded to a mildly cooked diet

Background

The gut microbiota (GM) is associated with canine health and can be impacted by diet. Dog owners in the U.S. have increasingly shown an interest in feeding their dogs a mildly cooked (MC) diet. However, its impact on canine GM and health remains largely unknown.

Methods

Healthy household dogs were tracked upon switching from various brands of extruded to MC diets for four weeks. A health assessment was completed and stool samples were collected by each owner before (day 0) and after the diet transition (day 28). Shotgun metagenomic sequencing was performed at both time points to characterize the GM.

Results

Dogs completed the study by either completing the health assessments (n = 31) or providing stool samples at both time points (n = 28). All owners reported either better or no change in overall health at the end of the study (61% and 39%, respectively), and none reported worse overall health. Defecation frequency was also reported to be lower (58%) or about the same (35%). Principal coordinate (PCo) analysis showed a significant shift (p = 0.004) in the β-diversity of the GM upon diet transition (34.2% and 10.3% explained by the first two axes). The abundances of 70 species increased after the diet change (adjusted p < 0.05), 67% and 24% of which belonged to the Lactobacillales and the Enterobacterales orders respectively. The abundances of 28 species decreased (adjusted p < 0.05), 46%, 18%, and 11% of which belonged to the Clostridiales, Bacillales, and Bacteroidales orders, respectively. Lower Lactobacillales and Enterobacterales, and higher Bacteroidales at baseline were associated with a greater shift along the PCo1 axis. Protein content of the baseline diet was correlated with the shift along the PCo1 axis (ρ = 0.67, p = 0.006).

Conclusion

Owners reported either improvement or no change in health in dogs transitioning from extruded kibble to MC diets for 4 weeks, but this report of health perception requires further exploration in a controlled trial. Diet change also led to a significant shift in the GM profile of healthy dogs. The magnitude of shift was associated with baseline GM and dietary protein, and warrants further examination of individualized responses and personalized nutrition in companion dogs. These results also support future investigation of the impact of a MC diet on health maintenance given its increasing popularity.

A review: nutrition and process attributes of corn in pet foods

Corn is one of the largest cereal crops worldwide and plays an important role in the U.S. economy. The pet food market is growing every year, and although corn is well utilized by dogs, some marketing claims have attributed a negative image to this cereal. Thus, the objective of this work was to review the literature regarding corn and its co-products, as well as describe the processing of these ingredients as they pertain to pet foods. Corn is well digested by both dogs and cats and provides nutrients. The processing of corn generates co-products such as corn gluten meal and distillers dried grains with solubles that retain quality protein, and fibrous components that dilute dietary energy. Further, corn has much functionality in extrusion processing. It may yield resistant starch under certain processing conditions, promoting colonic health. Carotenoids in corn may enhance immune support in companion animals if concentrated. Mycotoxin contamination in grains represent a health hazard but are well controlled by safety measures. Genetically modified (GM) corn is still controversial regarding its long-term potential for mutagenicity or carcinogenicity, thus more long-term studies are needed. In conclusion, the negative perception by some in the pet food market may not be warranted in pet foods using corn and its co-products.

Long non-coding RNA CASC9/microRNA-590-3p axis participates in lutein-mediated suppression of breast cancer cell proliferation

Previous studies have shown that lutein can inhibit the proliferation of breast cancer cells. However, the mechanism of lutein inhibiting the proliferation of breast cancer cells remains unclear. The present study aimed to determine whether the long non-coding RNA (lncRNA) Cancer Susceptibility 9 (CASC9)/microRNA (miR)-590-3p axis participates in the antiproliferative effects of lutein via lncRNA microarray hybridization, reverse transcription-quantitative PCR, dual-luciferase reporter and MTT assays. The results demonstrated that CASC9 was the most significantly downregulated lncRNA in MCF7 cells treated with lutein. miR-590-3p was identified as the target of CASC9. In addition, lutein downregulated CASC9 expression and upregulated miR-590-3p expression in dose- and time-dependent manners, respectively. CASC9 knockdown or overexpression of miR-590-3p inhibited the proliferation of breast cancer cells. Notably, simultaneous transfection with miR-590-3p mimics and CASC9 small interfering RNA increased the potency of lutein in inhibiting the proliferation of breast cancer cells. Taken together, these results suggest that the CASC9/miR-590-3p axis participates in the antiproliferative effects of lutein on breast cancer.

Plasma carotenoids and immunity in a despotic avian scavenger

Carotenoids are pigmented compounds acquired through diet that have important functions as antioxidants and immune modulators. We studied the association between immunity and circulating carotenoids in Andean condors (Vultur gryphus). We evaluated the relationship between α-, β-, and γ-globulin blood concentrations and different circulating carotenoids in two groups of Andean condors that differ in their mean health status, rehabilitating (suffering different pathologies), and wild individuals (trapped when displaying their physiological behavior). In rehabilitating individuals, α-, β-, and γ-globulin concentrations were higher than in wild individuals. This shows that rehabilitating individuals were developing an immune response associated with the pathologies that they were suffering at the time of sampling. In addition, circulating carotenoids were lower in rehabilitating than in wild individuals. We found negative correlations between α-, β-, and γ-globulins and different circulating carotenoids in rehabilitating individuals, but not in wild condors. Xanthophylls were strongly related to α-, β-, and γ-globulin blood concentrations in rehabilitating, but not in wild condors. Our results suggest that there is a potential relationship between circulating carotenoids and immunity in the Andean condor. Given that this species may display a carotenoid-based pigmentation, our results could suggest that a trade-off between the immune system and external coloration could operate in this species, which may have implications in their access to food resources and mate selection and, thus, in their conservation.

Active fractions of mannoproteins derived from yeast cell wall stimulate innate and acquired immunity of adult and elderly dogs

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Aging can promote changes in the immune system in dogs.

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Nutritional intervention in older dogs aims to increase lifespan.

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The yeast cell wall comprises β-(1,3)-D-glucan, β-(1,6)-D-glucan and mannoproteins.

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Elderly dogs when compared to adult dogs had lower absolute T and B lymphocyte counts.

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Mannoproteins stimulated acquired and innate immune responses in adult and elderly dogs.

Nutritional intervention in older dogs aims to increase lifespan and improve life quality as well as delay the development of diseases related to ageing. It is believed that active fractions of mannoproteins (AFMs) obtained through extraction and fractionation of yeast cell walls (Saccharomyces cerevisiae) may beneficially modulate the immune system. However, studies that have evaluated this component and the effects of ageing on the immune system of dogs are scarce. This study aimed to evaluate the immunological effects of AFMs in adult and elderly dogs. Three extruded iso-nutrient experimental diets were formulated: without addition of AFM (T0); with AFM at 400 mg/kg (T400); and with AFM at 800 mg/kg (T800). Thirty-six beagle dogs were used, and six experimental treatments, resulting in combinations of age (adult and elderly) and diet (T0, T400, and T800), were evaluated. On days zero, 14, and 28, blood samples were obtained for leucocyte phenotyping and phagocytosis assays. On days zero and 28, a lymphoproliferation test, quantification of reactive oxygen (H₂O₂) and nitrogen (NO) intermediate production, evaluation of faecal immunoglobulin A (IgA) content, and a delayed cutaneous hypersensitivity test (DCHT) were performed. Statistical analyses were performed with SAS software. Repeated measure variance analyses were performed, and means were compared by the Tukey test. Values of P ≤ 0.05 were considered significant, and values of P ≤ 0.10 were considered tendencies. Dogs fed T400 tended to have higher neutrophilic phagocytic activity than dogs fed T800 (P = 0.073). Regarding reactive oxygen intermediates, bacterial lipopolysaccharide (LPS)-stimulated neutrophils from animals that were fed T400 had a tendency to produce more H₂O₂ than those from animals fed the control diet (P = 0.093). Elderly dogs, when compared to adult dogs, had lower absolute T and B lymphocyte counts, lower auxiliary T lymphocyte counts, and higher cytotoxic T lymphocyte counts (P < 0.05). A significant effect of diet, age, and time with saline inoculation was noted for the DCHT. There was no effect of diet or age on faecal IgA content in dogs. This study suggests beneficial effects of mannoproteins on the specific and nonspecific immune responses in adult and elderly dogs.

Xanthophyll: Health benefits and therapeutic insights

Xanthophylls constitute a major part of carotenoids in nature. They are an oxidized version of carotenoid. Xanthophyll has widely drawn scientists' attentions in terms of its functionality, bioavailability and diversity. An assortment of xanthophyll varieties includes lutein, zeaxanthin, β-cryptoxanthin, capsanthin, astaxanthin, and fucoxanthin. Chemically, lutein and zeaxanthin are dipolar carotenoids with hydroxyl groups at both ends of their molecules that bestow hydrophilic properties to them. Hydrophilic affinity in lutein and zeaxanthin makes better bioavailability in reaction with singlet oxygen in water phase, whereas non-polar carotenoids have shown to have less efficiency in scavenging free radicals. Xanthophylls have been studied for their effects in a wide variety of diseases including neurologic, ophthalmologic, oral, allergic and immune diseases. This review highlights pharmaco-pharmaceutical applications of xanthophylls as well asits drug interactions with beta-carotene. Different types of xanthophylls have been shown to have neuroprotective effects. Fucoxanthin demonstrated potent antiplasmodial activity. Lutein and zeaxanthin prevent the progression of age related macular degeneration. They have also demonstrated promising effects on uveitis, retinitis pigmentosa, scleritis, cataracts, glaucoma, retinal ischemia and choroideremia. Astaxanthin showed to have skin protecting effects against ultraviolet light injury. Astaxanthin have anti-allergic activity against the contact dermatitis especially to treat the patients having adverse reactions induced by steroids. Astaxanthin has been reported to exert beneficial effects in preventing oral lichen planus and early stage cancers. β-cryptoxanthin has been considered a good candidate for prevention of bone loss via osteoblastic bone formation and inhibiting osteoclastic bone resorption. There is also some concern that higher dose of xanthophylls may be linked to increased risk of skin cancer and gastric adenocarcinoma. However this increased risk was not statistically significant when adjusted for confounding factors. Further researches including clinical studies are needed to better evaluate the efficacy and safety of xanthophylls in prevention and treatment of different diseases.

Probiotic Potential of a Lactobacillus Bacterium of Canine Faecal-Origin and Its Impact on Select Gut Health Indices and Immune Response of Dogs

The objective of the present study was to develop a probiotic of canine-origin for its potential application in pet nutrition. Accordingly, 32 lactic acid bacteria (LAB) strains were isolated from faeces of dogs, out of which 9 strains were short-listed for further in vitro testing based on the aggregation time and cell surface hydrophobicity. The results of acid-, bile- and phenol-tolerance tests indicated that out of the nine, isolate cPRO23 was having better resistance to these adverse conditions likely to be encountered in the gastrointestinal tract. The isolate also showed optimal enzymatic activities for amylase, lipase and protease. Further assessments also indicated its superiority in terms of co-aggregation and antagonistic activity against pathogenic strains of Salmonella typhimurium and Salmonella enteritidis. Subsequently, the isolate was identified through 16S rRNA sequencing and sequence homology, and designated as Lactobacillus johnsonii CPN23. The candidate probiotic was then evaluated in vivo using 15 adult Labrador dogs, divided into 3 groups, viz. CON (with no probiotics), dPRO (with Lactobacillus acidophilus NCDC 15 as a conventional dairy-origin probiotic) and cPRO (with L. johnsonii CPN23 as a canine-origin probiotic). Results of the 9-week study indicated that supplementation of cPRO improved (P < 0.05) the faecal concentration of acetate and butyrate with a concomitant reduction (P < 0.05) in faecal ammonia. The cell-mediated immune response, assessed as delayed-type hypersensitivity reaction to phytohaemagglutinin-P, was better (P < 0.05) in dogs fed cPRO as compared to the CON dogs. There were, however, no variations evident in the antibody response to sheep-erythrocytes among the three groups. It is concluded that the canine-origin L. johnsonii CPN23, in addition to possessing all the in vitro functional attributes of a candidate probiotic, also has the potential to be used as a probiotic in pet nutrition programs.

NrF2/ARE and NF-κB pathway regulation may be the mechanism for lutein inhibition of human breast cancer cell

Aim: Though lutein can inhibit cancer cell proliferation via alleviating oxidative injury, the molecular mechanisms of lutein involvement in the NrF2/antioxidant response element (ARE) and NF-κB pathways remain poorly understood. Materials & methods: MTT, flow cytometry, quantitative real-time PCR (qRT-PCR) and western blot assays were performed. Results: After treatment with lutein, breast cancer cell proliferation was significantly decreased in a dose-dependent manner. Lutein induced nuclear translocation and protein expression of NrF2, improved the expression of cellular antioxidant enzymes and attenuated reactive oxygen species levels. Moreover, lutein treatment decreased NF-κB signaling pathway related NF-κB p65 protein expression. Conclusion: The effect of lutein antiproliferation was mediated by activation of the NrF2/ARE pathway, and blocking of the NF-κB signaling pathway.

Comparative assessment of canine-origin Lactobacillus johnsonii CPN23 and dairy-origin Lactobacillus acidophillus NCDC 15 for nutrient digestibility, faecal fermentative metabolites and selected gut health indices in dogs

The present experiment was undertaken to validate a probiotic of canine origin for its potential use in dogs. A total of fifteen adult female Labrador dogs were allocated to three equal groups and fed a basal diet without probiotic (control) or with probiotic of either canine (Lactobacillus johnsonii CPN23; cPRO) or dairy (L. acidophilus NCDC 15; dPRO) origin for 9 weeks. The digestibility of most macronutrients remained similar among the groups; however, fibre digestibility was improved (P = 0·034) in dogs receiving cPRO. The faecal fermentative metabolites ammonia (P < 0·05) and lactate (P = 0·094) were altered favourably, indicating a positive influence of both probiotics. Faecal concentrations of acetate, propionate and butyrate were increased (P < 0·01) in both probiotic groups. However, improvements were higher in cPRO v. dPRO. The delayed-type hypersensitivity reaction to intradermal inoculation of phytohaemagglutinin-P was higher (P = 0·053) in cPRO as compared with control. The antibody response to sheep erythrocytes was, however, similar across the three groups. Overall, in dogs, the canine-origin probiotic was superior when compared with the dairy-origin probiotic.

Carotenoids: biochemistry, pharmacology and treatment

Carotenoids and retinoids have several similar biological activities such as antioxidant properties, the inhibition of malignant tumour growth and the induction of apoptosis. Supplementation with carotenoids can affect cell growth and modulate gene expression and immune responses. Epidemiological studies have shown a correlation between a high carotenoid intake in the diet with a reduced risk of breast, cervical, ovarian, colorectal cancers, and cardiovascular and eye diseases. Cancer chemoprevention by dietary carotenoids involves several mechanisms, including effects on gap junctional intercellular communication, growth factor signalling, cell cycle progression, differentiation-related proteins, retinoid-like receptors, antioxidant response element, nuclear receptors, AP-1 transcriptional complex, the Wnt/β-catenin pathway and inflammatory cytokines. Moreover, carotenoids can stimulate the proliferation of B- and T-lymphocytes, the activity of macrophages and cytotoxic T-cells, effector T-cell function and the production of cytokines. Recently, the beneficial effects of carotenoid-rich vegetables and fruits in health and in decreasing the risk of certain diseases has been attributed to the major carotenoids, β-carotene, lycopene, lutein, zeaxanthin, crocin (/crocetin) and curcumin, due to their antioxidant effects. It is thought that carotenoids act in a time- and dose-dependent manner. In this review, we briefly describe the biological and immunological activities of the main carotenoids used for the treatment of various diseases and their possible mechanisms of action.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Effect of dietary mannanoligosaccharide supplementation on nutrient digestibility, hindgut fermentation, immune response and antioxidant indices in dogs

BACKGROUND

Use of prebiotics in companion animal nutrition is often considered advantageous over probiotics because of the ease of handling, ability to withstand processing and storage etc. While most of the studies on prebiotic use in dogs have been done with processed food as basal diet, the response in relation to homemade diet feeding is not very well explored.

METHODS

The study was conducted to evaluate the effects of dietary mannanoligosaccharide (MOS) supplementation on nutrient digestibility, hindgut fermentation, immune response and antioxidant indices in dogs. Ten Spitz pups were divided into two groups: control (CON) with no supplementation, and experimental (MOS) wherein the basal diet was supplemented with MOS at 15 g/kg diet. All dogs were fed on a home-prepared diet for a period of 150 days. The study protocol included a digestion trial, periodic blood collection and analysis for lipid profile and erythrocytic antioxidants. Immune response of the animals was assessed towards the end of the feeding period.

RESULTS

Results revealed no significant (P > 0.05) variations in palatability score, intake and apparent digestibility of nutrients between the groups. Faecal score, faeces voided, faecal pH, concentrations of ammonia, lactate and short-chain fatty acids were comparable (P > 0.05) between the two groups. Cell-mediated immune response, assessed as delayed-type of hypersensitivity response, was significantly higher (P < 0.05) in the MOS group. The percent of lymphocyte sub-populations CD4+ and ratio of CD4+:CD8+ were also significantly (P < 0.05) higher in MOS group. The serum IgG levels were similar (P > 0.05) in both the groups. Supplementation of MOS lowered (P < 0.05) serum total- and LDL- cholesterol levels, when compared with the control group. The erythrocytic antioxidant indices were similar (P > 0.05) between the two groups.

CONCLUSIONS

The results indicated that supplementation of MOS at the rate of 15 g/kg in the diet of dog augmented the cell-mediated immune response and serum lipid profile without any influences on digestibility of nutrients, hindgut fermentation and antioxidants indices.

Anti-inflammatory and immunomodulatory properties of Carica papaya

Chronic inflammation is linked with the generation and progression of various diseases such as cancer, diabetes and atherosclerosis, and anti-inflammatory drugs therefore have the potential to assist in the treatment of these conditions. Carica papaya is a tropical plant that is traditionally used in the treatment of various ailments including inflammatory conditions. A literature search was conducted by using the keywords "papaya", "anti-inflammatory and inflammation" and "immunomodulation and immune" along with cross-referencing. Both in vitro and in vivo investigation studies were included. This is a review of all studies published since 2000 on the anti-inflammatory activity of papaya extracts and their effects on various immune-inflammatory mediators. Studies on the anti-inflammatory activities of recognized phytochemicals present in papaya are also included. Although in vitro and in vivo studies have shown that papaya extracts and papaya-associated phytochemicals possess anti-inflammatory and immunomodulatory properties, clinical studies are lacking.

Potential Anti-Atherosclerotic Properties of Astaxanthin

Astaxanthin is a naturally occurring red carotenoid pigment classified as a xanthophyll, found in microalgae and seafood such as salmon, trout, and shrimp. This review focuses on astaxanthin as a bioactive compound and outlines the evidence associated with its potential role in the prevention of atherosclerosis. Astaxanthin has a unique molecular structure that is responsible for its powerful antioxidant activities by quenching singlet oxygen and scavenging free radicals. Astaxanthin has been reported to inhibit low-density lipoprotein (LDL) oxidation and to increase high-density lipoprotein (HDL)-cholesterol and adiponectin levels in clinical studies. Accumulating evidence suggests that astaxanthin could exert preventive actions against atherosclerotic cardiovascular disease (CVD) via its potential to improve oxidative stress, inflammation, lipid metabolism, and glucose metabolism. In addition to identifying mechanisms of astaxanthin bioactivity by basic research, much more epidemiological and clinical evidence linking reduced CVD risk with dietary astaxanthin intake is needed.

The effects of lutein on cardiometabolic health across the life course: a systematic review and meta-analysis

BACKGROUND

The antioxidant lutein is suggested as being beneficial to cardiometabolic health because of its protective effect against oxidative stress, but evidence has not systematically been evaluated.

OBJECTIVE

We aimed to evaluate systematically the effects of lutein (intake or concentrations) on cardiometabolic outcomes in different life stages.

DESIGN

This is a systematic review with meta-analysis of literature published in MEDLINE, Embase, Cochrane Central, Web of Science, PubMed, and Google Scholar up to August 2014. Included were trials and cohort, case-control, and cross-sectional studies in which the association between lutein concentrations, dietary intake, or supplements and cardiometabolic outcomes was reported. Two independent investigators reviewed the articles.

RESULTS

Seventy-one relevant articles were identified that included a total of 387,569 participants. Only 1 article investigated the effects of lutein during pregnancy, and 3 studied lutein in children. Furthermore, 31 longitudinal, 33 cross-sectional, and 3 intervention studies were conducted in adults. Meta-analysis showed a lower risk of coronary heart disease (pooled RR: 0.88; 95% CI: 0.80, 0.98) and stroke (pooled RR: 0.82; 95% CI: 0.72, 0.93) for the highest compared with the lowest tertile of lutein blood concentration or intake. There was no significant association with type 2 diabetes mellitus (pooled RR: 0.97; 95% CI: 0.77, 1.22), but higher lutein was associated with a lower risk of metabolic syndrome (pooled RR: 0.75; 95% CI: 0.60, 0.92) for the highest compared with the lowest tertile. The literature on risk factors for cardiometabolic diseases showed that lutein might be beneficial for atherosclerosis and inflammatory markers, but there were inconsistent associations with blood pressure, adiposity, insulin resistance, and blood lipids.

CONCLUSIONS

Our findings suggest that higher dietary intake and higher blood concentrations of lutein are generally associated with better cardiometabolic health. However, evidence mainly comes from observational studies in adults, whereas large-scale intervention studies and studies of lutein during pregnancy and childhood are scarce.

Isolation and Analysis of the Cppsy Gene and Promoter from Chlorella protothecoides CS-41

Phytoene synthase (PSY) catalyzes the condensation of two molecules of geranylgeranyl pyrophosphate to form phytoene, the first colorless carotene in the carotenoid biosynthesis pathway. So it is regarded as the crucial enzyme for carotenoid production, and has unsurprisingly been involved in genetic engineering studies of carotenoid production. In this study, the psy gene from Chlorella protothecoides CS-41, designated Cppsy, was cloned using rapid amplification of cDNA ends. The full-length DNA was 2488 bp, and the corresponding cDNA was 1143 bp, which encoded 380 amino acids. Computational analysis suggested that this protein belongs to the Isoprenoid_Biosyn_C1 superfamily. It contained the consensus sequence, including three predicted substrate-Mg²⁺ binding sites. The Cppsy gene promoter was also cloned and characterized. Analysis revealed several candidate motifs for the promoter, which exhibited light- and methyl jasmonate (MeJA)-responsive characteristics, as well as some typical domains universally discovered in promoter sequences, such as the TATA-box and CAAT-box. Light- and MeJA treatment showed that the Cppsy expression level was significantly enhanced by light and MeJA. These results provide a basis for genetically modifying the carotenoid biosynthesis pathway in C. protothecoides.

Nutrition of aging dogs

Aging is a normal process characterized by a variety of physiologic changes. Geriatric dogs are also more likely to be afflicted with certain disease conditions. Both normal and abnormal physiologic changes associated with aging in the dog may be amenable to nutritional intervention. Specific alterations in nutrients or in dietary characteristics can be beneficial; however, these are best done in the context of an individualized nutritional assessment and monitoring paradigm.

Immune enhancement activities of silk lutein extract from Bombyx mori cocoons

Background

Declining immune function poses an important clinical challenge worldwide and supplementation with natural products that possessing immune enhancing properties is a promising approach for preventing or delaying immune function decline. Cocoons from yellow silkworms are a significant source of lutein, and this unexplored silk extract could be a viable alternative source for dietary lutein. This study assessed immunomodulatory activities of the silk lutein extract. Female BALB/c mice orally received lutein, either as silk or marigold extracts (10 or 20 mg/kg daily), or vehicle only (1% tween 80 in PBS pH 7.4) for 4 weeks. Natural killer (NK) cell activity, specific antibody production, lymphocyte subpopulations, mitogen-induced lymphocyte proliferation, and cytokine production were examined.

Results

Silk lutein extract increased NK cell activity, and the effect was dose-related whereas marigold lutein extract was ineffective. Silk lutein extract dose-dependently enhanced antibody production in pre-immunized mice but marigold lutein extract had no effect. Feeding with silk lutein extract increased the populations of CD3+ and CD4 + CD3 + cells. Silk lutein extract also stimulated concanavalin A- and lipopolysaccharide-induced proliferations of T and B lymphocytes, respectively. Moreover, silk lutein extract increased IL-2 and IFN-γ production while the effect of marigold lutein extract was undetectable.

Conclusions

Together, silk lutein extract enhanced both innate and adaptive immune functions. This preparation may prove to be an effective supplement for strengthened immunity.

Lutein: more than just a filter for blue light

Lutein is concentrated in the primate retina, where together with zeaxanthin it forms the macular pigment. Traditionally lutein is characterized by its blue light filtering and anti-oxidant properties. Eliminating lutein from the diet of experimental animals results in early degenerative signs in the retina while patients with an acquired condition of macular pigment loss (Macular Telangiectasia) show serious visual handicap indicating the importance of macular pigment. Whether lutein intake reduces the risk of age related macular degeneration (AMD) or cataract formation is currently a strong matter of debate and abundant research is carried out to unravel the biological properties of the lutein molecule. SR-B1 has recently been identified as a lutein binding protein in the retina and this same receptor plays a role in the selective uptake in the gut. In the blood lutein is transported via high-density lipoproteins (HDL). Genes controlling SR-B1 and HDL levels predispose to AMD which supports the involvement of cholesterol/lutein transport pathways. Apart from beneficial effects of lutein intake on various visual function tests, recent findings show that lutein can affect immune responses and inflammation. Lutein diminishes the expression of various ocular inflammation models including endotoxin induced uveitis, laser induced choroidal neovascularization, streptozotocin induced diabetes and experimental retinal ischemia and reperfusion. In vitro studies show that lutein suppresses NF kappa-B activation as well as the expression of iNOS and COX-2. Since AMD has features of a chronic low-grade systemic inflammatory response, attention to the exact role of lutein in this disease has shifted from a local effect in the eye towards a possible systemic anti-inflammatory function.

A naturally occurring carotenoid, lutein, reduces PDGF and H₂O₂ signaling and compromised migration in cultured vascular smooth muscle cells

Background

Platelet-derived growth factor (PDGF) is a potent stimulator of growth and motility of vascular smooth muscle cells (VSMCs). Abnormalities of PDGF/PDGF receptor (PDGFR) are thought to contribute to vascular diseases and malignancy. We previously showed that a carotenoid, lycopene, can directly bind to PDGF and affect its related functions in VSMCs. In this study we examined the effect of the other naturally occurring carotenoid, lutein, on PDGF signaling and migration in VSMCs.

Methods

Western blotting was performed to examine PDGF and H₂O₂ signaling. Flowcytometry was used to determine PDGF binding to VSMCs. Fluorescence microscopy was performed to examine intracellular ROS production. Modified Boyden chamber system (Transwell apparatus) was used for migration assay.

Results

Lutein reduced PDGF signaling, including phosphorylation of PDGFR-β and its downstream protein kinases/enzymes such as phospholipase C-γ, Akt, and mitogen-activated protein kinases (MAPKs). Although lutein possesses a similar structure to lycopene, it was striking that lutein inhibited PDGF signaling through a different way from lycopene in VSMCs. Unlike lycopene, lutein not only interacted with (bound to) PDGF but also interfered with cellular components. This was evidenced that preincubation of PDGF with lutein and treatment of VSMCs with lutein followed by removing of lutein compromised PDGF-induced signaling. Lutein reduced PDGF-induced intracellular reactive oxygen species (ROS) production and attenuated ROS- (H₂O₂-) induced ERK1/2 and p38 MAPK activation. A further analysis indicated lutein could inhibit a higher concentration of H₂O₂-induced PDGFR signaling, which is known to act through an oxidative inhibition of protein tyrosine phosphatase. Finally, we showed that lutein functionally inhibited PDGF-induced VSMC migration, whereas its stereo-isomer zeaxanthin did not, revealing a special action of lutein on VSMCs.

Conclusions

Our study reveals a differential action mechanism of lutein from other reported caroteinoids and suggests a possible beneficial effect of lutein but not zeaxanthin on prevention of vascular diseases.

Supplementation of xanthophylls decreased proinflammatory and increased anti-inflammatory cytokines in hens and chicks

The present study investigated the effects of xanthophylls (containing 40 % of lutein and 60 % of zeaxanthin) on proinflammatory cytokine (IL-1β, IL-6, interferon (IFN)-γ and lipopolysaccharide-induced TNF-α factor (LITAF)) and anti-inflammatory cytokine (IL-4 and IL-10) expression of breeding hens and chicks. In Expt 1, a total of 432 hens were fed diets supplemented with 0 (as the control group), 20 or 40 mg/kg xanthophylls (six replicates per treatment). The liver, duodenum, jejunum and ileum were sampled at 35 d of the trial. The results showed that both levels of xanthophyll addition decreased IL-1β mRNA in the liver and jejunum, IL-6 mRNA in the liver, IFN-γ mRNA in the jejunum and LITAF mRNA in the liver compared to the control group. Expt 2 was a 2 × 2 factorial design. Male chicks hatched from 0 or 40 mg/kg xanthophyll diet of hens were fed a diet containing either 0 or 40 mg/kg xanthophylls. The liver, duodenum, jejunum and ileum were collected at 0, 7, 14 and 21 d after hatching. The results showed that in ovo xanthophylls decreased proinflammatory cytokine expression (IL-1β, IL-6, IFN-γ and LITAF) in the liver, duodenum, jejunum and ileum and increased anti-inflammatory cytokine expression (IL-4 and IL-10) in the liver, jejunum and ileum mainly at 0-7 d after hatching. In ovo effects gradually vanished and dietary effects began to work during 1-2 weeks after hatching. Dietary xanthophylls modulated proinflammatory cytokines (IL-1β, IL-6 and IFN-γ) in the liver, duodenum, jejunum and ileum and anti-inflammatory cytokine (IL-10) in the liver and jejunum mainly from 2 weeks onwards. In conclusion, xanthophylls could regulate proinflammatory and anti-inflammatory cytokine expression in different tissues of hens and chicks.

Effect of Thuja occidentalis and its polysaccharide on cell-mediated immune responses and cytokine levels of metastatic tumor-bearing animals

CONTEXT

Tumor microenvironment induces an active immune tolerance and escapes immune surveillance. In order to achieve an effective antitumor immune response, appropriately activated immune cells should maintain their antitumor activity to overcome the immune suppressive tumor microenvironment.

OBJECTIVES

This study focuses on the effect of Thuja occidentalis L. (Cupressaceae) extract and its polysaccharide (TPS) on cell-mediated immune response (CMI) in metastasis bearing mice.

MATERIALS AND METHODS

Metastasis was induced by injecting B16F-10 melanoma cells in mice through the tail vein and effector mechanisms of CMI was studied by analyzing cytotoxic T-lymphocyte (CTL) activity, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent complement-mediated cytotoxicity (ACC). The effect of T. occidentalis and TPS on pro-inflammatory cytokines and tissue inhibitor matrix metalloproteinases (TIMP) levels were also analyzed.

RESULTS AND DISCUSSION

Administration of T. occidentalis and TPS enhanced the NK cell activity, ADCC and ACC much earlier than the control tumor-bearing animals. T. occidentalis and TPS were also found to decrease the elevated level of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, GM-CSF and tumor necrosis factor (TNF)-α in the serum of metastatic tumor-bearing animals. The level of antitumor factors such as IL-2 and TIMP was elevated by the treatment with T. occidentalis and TPS in the serum, which was lowered in the untreated tumor-bearing animals.

CONCLUSION

This study clearly suggests that T. occidentalis and TPS effectively stimulate cell-mediated immune system and decrease pro-inflammatory cytokines, thereby inhibiting metastasis of tumor cells.

Enhancement of lutein production in Chlorella sorokiniana (Chorophyta) by improvement of culture conditions and random mutagenesis

Chlorella sorokiniana has been selected for lutein production, after a screening of thirteen species of microalgae, since it showed both a high content in this carotenoid and a high growth rate. The effects of several nutritional and environmental factors on cell growth and lutein accumulation have been studied. Maximal specific growth rate and lutein content were attained at 690 μmol photons m⁻² s⁻¹, 28 °C, 2 mM NaCl, 40 mM nitrate and under mixotrophic conditions. In general, optimal conditions for the growth of this strain also lead to maximal lutein productivity. High lutein yielding mutants of C. sorokiniana have been obtained by random mutagenesis, using N-methyl-N′-nitro-nitrosoguanidine (MNNG) as a mutagen and selecting mutants by their resistance to the inhibitors of the carotenogenic pathway nicotine and norflurazon. Among the mutants resistant to the herbicides, those exhibiting both high content in lutein and high growth rate were chosen. Several mutants exhibited higher contents in this carotenoid than the wild type, showing, in addition, either a similar or higher growth rate than the latter strain. The mutant MR-16 exhibited a 2.0-fold higher volumetric lutein content than that of the wild type, attaining values of 42.0 mg L⁻¹ and mutants DMR-5 and DMR-8 attained a lutein cellular content of 7.0 mg g⁻¹ dry weight. The high lutein yield exhibited by C. sorokiniana makes this microalga an excellent candidate for the production of this commercially interesting pigment.

Astaxanthin stimulates cell-mediated and humoral immune responses in cats

Astaxanthin is a potent antioxidant carotenoid and may play a role in modulating immune response in cats. Blood was taken from female domestic shorthair cats (8-9 mo old; 3.2 ± 0.04 kg body weight) fed 0, 1, 5 or 10mg astaxanthin daily for 12 wk to assess peripheral blood mononuclear cell (PBMC) proliferation response, leukocyte subpopulations, natural killer (NK) cell cytotoxic activity, and plasma IgG and IgM concentration. Cutaneous delayed-type hypersensitivity (DTH) response against concanavalin A and an attenuated polyvalent vaccine was assessed on wk 8 (prior to vaccination) and 12 (post-vaccination). There was a dose-related increase in plasma astaxanthin concentrations, with maximum concentrations observed on wk 12. Dietary astaxanthin enhanced DTH response to both the specific (vaccine) and nonspecific (concanavalin A) antigens. In addition, cats fed astaxanthin had heightened PBMC proliferation and NK cell cytotoxic activity. The population of CD3(+) total T and CD4(+) T helper cells were also higher in astaxanthin-fed cats; however, no treatment difference was found with the CD8(+) T cytotoxic and MHC II(+) activated lymphocyte cell populations. Dietary astaxanthin increased concentrations of plasma IgG and IgM. Therefore, dietary astaxanthin heightened cell-mediated and humoral immune responses in cats.

Augmentation of cellular immune response by Ipomoea obscura and Ipobscurine alkaloid attenuates tumor growth in mice

The immune status of the host plays a crucial role in controling the process of carcinogenesis. General or selective activation of various immunocompetent cells and their secretory function to maintain a healthy immune status may help in cancer prophylaxis, as well as therapy. The present study focused on the effect of Ipomoea obscura and Ipobscurine on cell-mediated immune response. In this study we evaluated the effect of I. obscura and an indole alkaloid fraction from I. obscura on effector mechanisms of cell-mediated immune response by analyzing cytotoxic T lymphocyte (CTL) activity, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and antibody-dependent complement-mediated cytotoxicity (ACC). The effect of I. obscura and Ipobscurine on interleukin-2 (IL-2) and interferon-γ (IFN-γ) levels was also analyzed. In the in vitro and in vivo systems, I. obscura and Ipobscurine treatment augmented cell-mediated immune response by enhancing the killing activity of CTL and NK cells from splenocytes in normal as well as tumor-bearing mice. ADCC and ACC were also enhanced significantly in both normal and tumor-bearing animals after drug administration, compared with untreated control. Administration of I. obscura and Ipobscurine significantly enhanced the production of IL-2 and IFN-γ in normal as well as tumor-bearing animals. This study reveals that both I. obscura and Ipobscurine have the potential to augment immune response through the enhanced secretion of IL-2 and IFN-γ by T cells and thereby inhibit tumor growth and as an alternative medicine for cancer treatment.

Astaxanthin decreased oxidative stress and inflammation and enhanced immune response in humans

Background

Astaxanthin modulates immune response, inhibits cancer cell growth, reduces bacterial load and gastric inflammation, and protects against UVA-induced oxidative stress in in vitro and rodent models. Similar clinical studies in humans are unavailable. Our objective is to study the action of dietary astaxanthin in modulating immune response, oxidative status and inflammation in young healthy adult female human subjects.

Methods

Participants (averaged 21.5 yr) received 0, 2, or 8 mg astaxanthin (n = 14/diet) daily for 8 wk in a randomized double-blind, placebo-controlled study. Immune response was assessed on wk 0, 4 and 8, and tuberculin test performed on wk 8.

Results

Plasma astaxanthin increased (P < 0.01) dose-dependently after 4 or 8 wk of supplementation. Astaxanthin decreased a DNA damage biomarker after 4 wk but did not affect lipid peroxidation. Plasma C-reactive protein concentration was lower (P < 0.05) on wk 8 in subjects given 2 mg astaxanthin. Dietary astaxanthin stimulated mitogen-induced lymphoproliferation, increased natural killer cell cytotoxic activity, and increased total T and B cell subpopulations, but did not influence populations of T_helper, T_cytotoxic or natural killer cells. A higher percentage of leukocytes expressed the LFA-1 marker in subjects given 2 mg astaxanthin on wk 8. Subjects fed 2 mg astaxanthin had a higher tuberculin response than unsupplemented subjects. There was no difference in TNF and IL-2 concentrations, but plasma IFN-γ and IL-6 increased on wk 8 in subjects given 8 mg astaxanthin.

Conclusion

Therefore, dietary astaxanthin decreases a DNA damage biomarker and acute phase protein, and enhances immune response in young healthy females.

Do carotenoids serve as transmembrane radical channels?

Carotenoids are a diverse group of terpenoid pigments that originated in prokaryotes over 3 billion years ago. Their primary function in plants is to serve as photomodulators of the oxidizing side of Photosystem II. In animals, which must acquire carotenoids from their diets, carotenoids serve a host of functions and are viewed primarily as efficient scavengers of singlet oxygen and radicals within the domain of membranes where they reside. Recently it has been demonstrated that carotenoids react cooperatively and synergistically with vitamin C and E, serving to regenerate a pro-oxidant radical carotenoid after the antioxidant reduction of a radical species. The exact location and behavior of carotenoids within biological membrane systems remain largely unknown. A hypothesis is proposed suggesting that carotenoids may serve as transmembrane radical channels. In this capacity carotenoids may reduce radicals in one biological compartment, while simultaneously being reduced in another. The benefit of rapid radical quenching across membrane compartments by transmembrane-spanning carotenoids such as zeaxanthin and lutein may be especially advantageous to intra- and extracellular redox control.

Effects of bovine lactoferrin on the immune system and the intestinal microflora of adult dogs

Eighteen Beagle dogs were used to evaluate the effects of bovine lactoferrin (bLF) on immune function and faecal microbial populations. The study comprised three feeding periods, each lasting four weeks. After an initial control Period 1, six dogs per group were supplemented with 0, 120 and 1800 mg bLF/kg dry diet, respectively (Period 2). In Period 3 dogs received again control diets. Peripheral blood mononuclear cell subsets, lymphocyte proliferative response to concanavalin A, phytohaemagglutinin and pokeweed mitogen and plasma IgA and IgG concentrations were analysed. The faecal concentrations of aerobic and anaerobic bacteria, Escherichia coli, Clostridium perfringens, Lactobacillus spp. and Bifidobacterium spp. were determined by cultural methods. Supplementation of bLF increased the number of monocytes, T cells and cytotoxic T cells in the blood and the proliferative response of peripheral blood mononuclear cells. The leukocyte counts were not affected, except monocytes that increased after the supplementation with bLF. Plasma immunoglobulin concentrations were unchanged by treatment. Dogs supplemented with bLF tended to have lower faecal concentrations of E. coli and Clostridium perfringens. In conclusion, bLF seems to alter indices of the cellular immune response and faecal microbial populations of healthy adult dogs.

Carotenoid trade-off between parasitic resistance and sexual display: an experimental study in the blackbird (Turdus merula)

Many parasites depress the expression of the carotenoid-based colour displays of their hosts, and it has been hypothesized that animals face a trade-off in carotenoid allocation between immune functions and 'degree of ornamentation'. While numerous correlative studies suggest that parasite infection decreases the intensity of carotenoid-based colour displays, the existence of this trade-off has never been demonstrated experimentally in a host-parasite model. In this study, we used the blackbird (Turdus merula) and Isospora (an intestinal parasite) to assess whether this trade-off does indeed exist. Blackbirds were supplemented with carotenoids while simultaneously being exposed to parasites. Supplemented males circulated more carotenoids in the blood and developed more brightly coloured bills than unsupplemented males. In addition, supplementation slowed down the replication rate of parasites. Supplementation with carotenoids enabled infected birds to maintain their bill coloration, whereas birds that were infected but not supplemented showed reduced bill coloration. At the same time, infection slowed carotenoid assimilation in the blood. Overall, we demonstrated that bill colour reflects a bird's health, and that only males with a carotenoid-rich diet are capable of coping with costs associated with parasitic infection. Carotenoids are thus traded off between host physiological response to parasites and secondary sexual traits. Further investigations are required to determine the physiological mechanisms that govern this trade-off.

Nutrition-based health in animal production

Events such as BSE, foot and mouth disease and avian influenza illustrate the importance of animal health on a global basis. The only practical solution to deal with such problems has usually been mass culling of millions of animals at great effort and expense. Serious consideration needs to be given to nutrition as a practical solution for health maintenance and disease avoidance of animals raised for food. Health or disease derives from a triad of interacting factors; diet–disease agent, diet–host and disease agent–host. Various nutrients and other bioactive feed ingredients, nutricines, directly influence health by inhibiting growth of pathogens or by modulating pathogen virulence. It is possible to transform plant-based feed ingredients to produce vaccines against important diseases and these could be fed directly to animals. Nutrients and nutricines contribute to three major factors important in the diet–host interaction; maintenance of gastrointestinal integrity, support of the immune system and the modulation of oxidative stress. Nutrition-based health is the next challenge in modern animal production and will be important to maintain economic viability and also to satisfy consumer demands in terms of food quality, safety and price. This must be accomplished largely through nutritional strategies making optimum use of both nutrients and nutricines.