Conjugated linoleic acids alleviate the immunosuppression of peripheral blood T lymphocytes in broiler chickens exposed to cyclosporin A

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Immunomodulatory effect of γ-irradiated Astragalus polysaccharides on immunosuppressed broilers

In this study, we irradiated Astragalus polysaccharides (APS) using 25 kGy ⁶⁰ Co γ ray to obtain γ-irradiated Astragalus polysaccharides (IAPS) and then investigated the effects of IAPS on growth performance and immune function of cyclophosphamide (CPM)-treated broilers. The physicochemical properties of APS and IAPS (molecular weight, water solubility, viscosity, morphological and structural properties) were evaluated. Then, 384 one-day-old Arbor Acres broiler chicks with similar initial weight were randomly assigned into 6 groups: the non-treated group (control), and CPM-treated groups were fed either a basal diet or the diets containing 900 mg/kg APS, or 900, 600, 300 mg/kg IAPS, respectively. On days 16, 18, and 20, all broilers except for the control group were intramuscularly injected with 0.5 ml CPM (40 mg/kg·BW). Broilers in the control group were intramuscularly injected with 0.5 ml sterilized saline (0.75%, wt/vol). This trial lasted for 21 days. The physicochemical treatment showed that γ irradiation could decrease the molecular weight and viscosity, and increase the water solubility of APS (p < 0.05), whereas the structural properties of APS was not affected. In the animal trial, 900 mg/kg APS or 900, 600 mg/kg IAPS relieved the decreased growth performance, thymus index, T lymphocytes proliferation, serum IgG concentration, NOS activity and the increased blood heterophil:lymphocyte ratio in CPM-treated broilers (p < 0.05). CPM-induced decreases in B lymphocytes proliferation and serum IgM concentration were only increased by IAPS at 900 mg/kg (p < 0.05). Overall, both APS and IAPS alleviated CPM-induced immunosuppression. Especially, IAPS possessed better immunomodulatory effect than APS, indicating that γ irradiation could be used as an effective method to enhance the immunomodulatory activity of APS.

Conjugated linoleic acid: A potent fatty acid linked to animal and human health

Conjugated linoleic acid (CLA) is a mixture of isomers of linoleic acid (C18:2 n-6), which is mostly found in the ruminant meat and dairy products. The CLA is known to have many potential health benefits, and considered a potent powerful fatty acid, which is linked to animal and human health. The present work aims to discuss the source and production, mechanism of action, and effects of CLA on humans, poultry, and ruminants by reviewing the recent studies carried out on CLA. Despite most of the recent studies indicating beneficial effects of CLA on improving body weight control parameters, its effects on reducing risk factors of cardiovascular diseases (CVD), inflammation, blood glucose, and insulin are still controversial, and need to be further studied in different hosts.

Effects of dietary conjugated linoleic acid on cytotoxicity of peripheral blood lymphocytes in piglets

The aim of this study was to investigate the effects of dietary conjugated linoleic acid (CLA) on the cytotoxicity of peripheral blood lymphocytes in piglets. A total of forty 21-d-old Duroc × Large White × Landrace weaned piglets were randomly allocated into two treatment groups and fed with control diet or 2% CLA diet for 6 weeks. Dietary CLA significantly increased the number of peripheral blood CD8+ T lymphocytes (P < 0.05). Compared with the control group, cytotoxicity, perforin, and granzyme B mRNA expression of peripheral blood lymphocytes in piglets from the CLA-supplementation group increased by 29.98% (P < 0.01), 32.87% (P < 0.01), and 43.36% (P < 0.05), respectively. The piglets on the CLA diet had higher mRNA expression of Lck and Fyn in peripheral blood lymphocytes (P < 0.05). The content of C16:0 significantly increased in piglets from the dietary CLA-supplementation group (P < 0.05), whereas the content of C18:1 significantly decreased (P < 0.05). The CLA content of peripheral blood lymphocytes in piglets in the CLA diet group ranged up to 0.24% (P < 0.01). These results suggest that dietary CLA enhanced cytotoxicity of peripheral blood lymphocytes perhaps through changing its fatty acid composition.

Effect of vitamin E on milk composition of grazing dairy cows supplemented with microencapsulated conjugated linoleic acid

The objective of this study was to evaluate the effect of vitamin E on the fat content and fatty acid profile of grazing dairy cows supplemented with microencapsulated conjugated linoleic acid. Eight New Zealand Holstein cows in a rotational grazing system were used, in a crossover design, randomly assigned to four treatments: control (base diet with microencapsulated conjugated linoleic acid) and three levels of vitamin E (control with 4,000; 8,000; and 12,000 IU/cow per day). All the cows received a supplement apportioning 5 g of cis-9, trans-11, and 5 g of trans-10, cis-12 of conjugated linoleic acid. Moreover, they each received 4-kg dry matter (DM) concentrate and 3.2-kg DM corn silage every day. There were no differences in dry matter intake, milk production, milk composition (fat, protein, and lactose), or fatty acid profile as an effect of vitamin E, and fat content remained under 3 % in all treatments. Therefore, under the conditions that this experiment was carried out, high concentrations of vitamin E in the diet of grazing dairy cows do not inhibit milk fat depression associated with conjugated linoleic acid. It also has no effect on the fatty acid profile of the milk.