Differences in the regulation of biosynthesis of 20- versus 22-carbon polyunsaturated fatty acids

Poultry Meat and Eggs as an Alternative Source of n-3 Long-Chain Polyunsaturated Fatty Acids for Human Nutrition

The beneficial effects of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) on human health are widely known. Humans are rather inefficient in synthesizing n-3 LC-PUFA; thus, these compounds should be supplemented in the diet. However, most Western human diets have unbalanced n-6/n-3 ratios resulting from eating habits and the fact that fish sources (rich in n-3 LC-PUFA) are not sufficient (worldwide deficit ~347,956 t/y) to meet the world requirements. In this context, it is necessary to find new and sustainable sources of n-3 LC-PUFA. Poultry products can provide humans n-3 LC-PUFA due to physiological characteristics and the wide consumption of meat and eggs. The present work aims to provide a general overview of the main strategies that should be adopted during rearing and postproduction to enrich and preserve n-3 LC-PUFA in poultry products. The strategies include dietary supplementation of α-Linolenic acid (ALA) or n-3 LC-PUFA, or enhancing n-3 LC-PUFA by improving the LA (Linoleic acid)/ALA ratio and antioxidant concentrations. Moreover, factors such as genotype, rearing system, transport, and cooking processes can impact the n-3 LC-PUFA in poultry products. The use of a multifactorial view in the entire production chain allows the relevant enrichment and preservation of n-3 LC-PUFA in poultry products.

Omega-3 fatty acids decrease CRYAB, production of oncogenic prostaglandin E2 and suppress tumor growth in medulloblastoma

AIMS

Medulloblastoma (MB) is one of the most common malignant central nervous system tumors of childhood. Despite intensive treatments that often leads to severe neurological sequelae, the risk for resistant relapses remains significant. In this study we have evaluated the effects of the ω3-long chain polyunsaturated fatty acids (ω3-LCPUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on MB cell lines and in a MB xenograft model.

MAIN METHODS

Effects of ω3-LCPUFA treatment of MB cells were assessed using the following: WST-1 assay, cell death probes, clonogenic assay, ELISA and western blot. MB cells were implanted into nude mice and the mice were randomized to DHA, or a combination of DHA and EPA treatment, or to control group. Treatment effects in tumor tissues were evaluated with: LC-MS/MS, RNA-sequencing and immunohistochemistry, and tumors, erythrocytes and brain tissues were analyzed with gas chromatography.

KEY FINDINGS

ω3-LCPUFA decreased prostaglandin E2 (PGE₂) secretion from MB cells, and impaired MB cell viability and colony forming ability and increased apoptosis in a dose-dependent manner. DHA reduced tumor growth in vivo, and both PGE₂ and prostacyclin were significantly decreased in tumor tissue from treated mice compared to control animals. All ω3-LCPUFA and dihomo-γ-linolenic acid increased in tumors from treated mice. RNA-sequencing revealed 10 downregulated genes in common among ω3-LCPUFA treated tumors. CRYAB was the most significantly altered gene and the downregulation was confirmed by immunohistochemistry.

SIGNIFICANCE

Our findings suggest that addition of DHA and EPA to the standard MB treatment regimen might be a novel approach to target inflammation in the tumor microenvironment.

Body surface area-based omega-3 fatty acids supplementation strongly correlates to blood concentrations in children

Omega-3 fatty acids have been suggested as a complement in cancer treatment, but doses are not established. We performed a dose-finding study in 33 children in remission from cancer. Participants were allocated to a body surface area (BSA) adjusted dose (mg/m²) of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (40:60), ranging 233-3448 mg/m² daily for 90 days. Fatty acid concentration in plasma phospholipids and red blood cells were determined by GC. Supplementation was well tolerated and correlated strongly with blood ω3-fatty acid concentrations and EPA showed the highest increase. Using the ω3-index disregards docosapentaenoic acid (DPA), which increased 30-43% in our study motivating an EDD-index (∑EPA,DPA,DHA). The ratio between arachidonic acid and EPA or DHA showed negative exponential trends. Dose per BSA enabled an individualized omega-3 supplementation decreasing the variation referred to interindividual differences. Based on our results, we suggest a dose of 1500 mg/m² BSA for further studies.

Biomarkers of Docosahexaenoic Acid but Not Arachidonic Acid Reflect Dietary Intakes in Toddlers at Ages 1 and 2 Years Who Are Not Meeting Dietary Recommendations

BACKGROUND

Long-chain n-6 and n-3 PUFAs are important for growth and development. However, little is known about requirements and current dietary intakes of these fatty acids in toddlers.

OBJECTIVES

This study assessed dietary intakes of n-6 and n-3 PUFAs and determined the relation to circulating PUFAs in toddlers at ages 1 and 2 y.

METHODS

This is a secondary analysis of data from toddlers enrolled in a double-blind randomized controlled trial of arachidonic acid (ARA) and DHA supplementation between ages 1 and 2 y. Dietary intakes of fatty acids were estimated by 3-d food records, and fatty acid composition in plasma total phospholipids, red blood cell phosphatidylethanolamine (PE), and phosphatidylcholine (PC) were assessed by GC at baseline in all subjects (n = 110; mean age 1.12 y; 64% male) and in the control subjects at 2 y (n = 43).

RESULTS

The dietary intakes of ARA, EPA, and DHA at age 1 y (baseline) were [mean (median)] 36.8 (30.0), 16.0 (0.00), and 31.1 (10.0) mg/d, respectively. Dietary intakes increased to 52.7 (45.0), 35.8 (0.00), and 64.8 (20.0) mg/d, respectively, at age 2 y (P < 0.05). The predominant dietary source of EPA and DHA was fish/seafood; eggs were an important source of ARA and DHA. Dietary DHA intakes were positively associated with plasma PE and PC DHA (P < 0.05). No relations between dietary ARA intakes and plasma PE and PC ARA (P > 0.05) were observed.

CONCLUSIONS

These findings suggest that most toddlers are not meeting the recommendation for dietary PUFA intakes and that higher dietary DHA intakes are reflected in plasma PE and PC DHA composition. Further work is required to investigate a biomarker for dietary ARA intake. This trial is registered at clinicaltrials.gov as NCT01263912.

Redefining essential fatty acids in the era of novel intravenous lipid emulsions

The essentiality of fatty acids was determined by the Burrs in the 1920s. It is commonly accepted that provision of linoleic (LA) and alpha-linolenic acids (ALA) prevents and reverses essential fatty acid deficiency (EFAD). Development of alternative injectable lipid emulsions (ILE) low in LA and ALA has raised concern about their ability to prevent EFAD. This review provides biochemical evidence coupled with observations from animal and human studies that aim to characterize which fatty acids are truly essential to prevent EFAD. Retroconversion pathways and mobilization from body stores suggest that arachidonic and docosahexaenoic acids (ARA and DHA - the main derivatives of LA and ALA, respectively) also prevent EFAD. Our group first proposed the essentiality of ARA and DHA by feeding mice exclusively these fatty acids and proving that they prevent EFAD. Survival for 5 generations on this diet provides additional evidence that growth and reproductive capabilities are maintained. Moreover, the use of fish oil-based ILE, with minimal LA and ALA and abundant DHA and ARA, for treatment of intestinal failure-associated liver disease, does not result in EFAD. These findings challenge the essentiality of LA and ALA in the presence of ARA and DHA. Evidence discussed in this review supports the idea that ARA and DHA can independently fulfill dietary essential fatty acid requirements. The imminent introduction of new ILE rich in ARA and DHA in the United States highlights the importance of understanding their essentiality, especially when provision of ALA and LA is below the established daily minimum requirement.

In vivo protective role against water contamination with cerium via chronic administration of omega 3

In the present study, adult, healthy male Wistar rats (120 ± 10 g) were pre-treated by intragastric administration of cerium chloride (CeCl₃) 10 mg/kg (BW) each day during 60 days. Control animal were treated with omega 3, a polyunsaturated fatty acid (ω-3), by an intragastric administration at 10 mg/kg of BW for 60 days. Our results showed that CeCl₃-induced alterations in all tested oxidative stress markers. In fact, CeCl₃-induced the increase the level of both the creatinine concentration and the expression of lactate dehydrogenase, alkaline phosphatase, and transaminase activities in serum. On the other hand, CeCl₃ significantly increased the levels of lipid peroxidation in the renal and hepatic tissues. The capacity of CeCl₃ to generate reactive oxygen species (ROS) could explain his ability to induce morphological alterations, such as centrilobular hemorrhage, hepatic necrosis, and vacuolization of the cytoplasm in hepatic tissues, and the atrophy of the glomerulus and dilatation of urinary space in renal tissues. However, omega 3, after gastric administration, reduced significantly the toxic effect caused by CeCl₃ according to his high ability to scavenge ROS. The present study indicates that omega 3 is a significant compound with protective activity against intoxication with heavy metal, the cerium, and thus may be useful for chemoprevention.

Dietary alpha-linolenic acid enhances omega-3 long chain polyunsaturated fatty acid levels in chicken tissues

The effects of enriching broiler chicken diets with a vegetable source of n-3 fat in the form of alpha-linolenic acid (ALA, 18:3n-3) on the accumulation of n-3 long chain polyunsaturated fatty acids (LCPUFA) in chicken meat were investigated. Sixty unsexed one-day-old broiler chickens (Cobb 500) were randomly allocated to one of six diets (n=10 birds/diet) for 4 weeks. The ALA levels varied from 1 to 8% energy (%en) while the level of the n-6 fatty acid linoleic acid (LA, 18:2n-6) was held to less than 5%en in all diets. At harvest (day 28) the levels of n-3 LCPUFA including eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) in breast and thigh meat increased in a curvilinear manner as dietary ALA increased, reaching 4- to 9-fold above the levels seen in control birds. In contrast, arachidonic acid (AA) was reduced in response to increasing dietary ALA.

Hyperlipidemia and reproductive failure in captive-reared alligators: vitamin E, vitamin A, plasma lipids, fatty acids, and steroid hormones

Blood samples were collected from 26 captive-reared alligators (25 females; one male) and 12 (seven females and five males) wild "nuisance" alligators collected by wildlife personnel in south Louisiana in May 1995. The captive alligators, hatched from artificially incubated eggs in 1972-1973, had received vitamin E supplements during the 3 weeks before the blood sample was collected. Each sample was analyzed for vitamin E (alpha-tocopherol), vitamin A (retinol), total lipid, triacylglycerol, phospholipid, cholesterol, cholesteryl ester, free fatty acids, steroid hormones and a standard clinical blood panel. The fatty acid composition of the plasma lipid fraction was also analyzed. Results indicated that 18 of the captive females and three of the seven wild females were undergoing vitellogenesis, i.e. had elevated plasma estradiol and elevated plasma calcium. Vitellogenic females had higher vitamin E than non-vitellogenic females (77.4 microg/ml vs. 28.6 microg/ml in captive females; 24.0 microg/ml vs. 21 microg/ml in wild females). Plasma retinol was similar in all groups, ranging from 0.5 to 1.4 microg/ml and close to values reported in birds. All lipid fractions, with the exception of cholesteryl ester, were higher in captive alligators than in wild alligators. There were also significant differences in the fatty acid composition of wild and captive alligators. Plasma eicosapentaenoic and docasahexaenoic acid were higher in wild than in captive alligators, whereas linoleic was higher in captive than in wild.

The Delta8-desaturase of Euglena gracilis: an alternate pathway for synthesis of 20-carbon polyunsaturated fatty acids

Desaturation of fatty acids is an important metabolic process. In mammals, 20-carbon and longer polyunsaturated fatty acids are not only incorporated into cellular membranes in a tissue-specific manner, but also serve as the precursors to synthesis of eicosanoid metabolic regulators. The processes of desaturation and elongation in human liver are well characterized, but an alternate Delta8 desaturation pathway that may be important in certain tissues or in cancer cells is less well examined. The Delta8-desaturase enzyme introduces a double bond at the 8-position in 20-carbon fatty acids that have an existing Delta11 unsaturation. We have isolated the first fatty acid Delta8-desaturase, from the protist Euglena gracilis, in order to explore this alternate pathway. A full-length cDNA was obtained after reverse transcription of mRNA purified from heterotrophically grown Euglena, followed by PCR amplification with primers degenerate to conserved histidine-rich regions of microsomal desaturases. The protein predicted from the cDNA sequence is highly homologous to Delta5 and Delta6 desaturases of Caenhorabditis elegans. When the cDNA was expressed in Saccharomyces cerevisiae, the yeast cultures readily desaturated appropriate 20-carbon fatty acids by inserting an additional double bond at the Delta8-position. The enzyme demonstrated a preference for substrates of metabolic significance, 20:3 Delta11,14,17 and 20:2 Delta11,14. Cloning of a Delta8 fatty acid desaturase offers the opportunity to examine an alternate pathway of long chain fatty acid biosynthesis.