Does Oil Rich in Alpha-Linolenic Fatty Acid Cause the Same Immune Modulation as Fish Oil in Walker 256 Tumor-Bearing Rats?

Current Insights into the Effects of Dietary α-Linolenic Acid Focusing on Alterations of Polyunsaturated Fatty Acid Profiles in Metabolic Syndrome

The plant-derived α-linolenic acid (ALA) is an essential n-3 acid highly susceptible to oxidation, present in oils of flaxseeds, walnuts, canola, perilla, soy, and chia. After ingestion, it can be incorporated in to body lipid pools (particularly triglycerides and phospholipid membranes), and then endogenously metabolized through desaturation, elongation, and peroxisome oxidation to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with a very limited efficiency (particularly for DHA), beta-oxidized as an energy source, or directly metabolized to C18-oxilipins. At this moment, data in the literature about the effects of ALA supplementation on metabolic syndrome (MetS) in humans are inconsistent, indicating no effects or some positive effects on all MetS components (abdominal obesity, dyslipidemia, impaired insulin sensitivity and glucoregulation, blood pressure, and liver steatosis). The major effects of ALA on MetS seem to be through its conversion to more potent EPA and DHA, the impact on the n-3/n-6 ratio, and the consecutive effects on the formation of oxylipins and endocannabinoids, inflammation, insulin sensitivity, and insulin secretion, as well as adipocyte and hepatocytes function. It is important to distinguish the direct effects of ALA from the effects of EPA and DHA metabolites. This review summarizes the most recent findings on this topic and discusses the possible mechanisms.

The potential effects of polyunsaturated ω-3 fatty acids on spinal cord injury: A systematic review & meta-analysis of preclinical evidence

Polyunsaturated fatty acids (PUFAs) have received attention for their anti-inflammatory and antioxidant properties. Preclinical studies have investigated the efficacy of PUFAs in animal models of spinal cord injury (SCI) to determine if these properties can translate to neuroprotection and locomotor recovery. Findings from such studies have been promising, suggesting PUFAs as potential treatments against the neurological dysfunction induced by SCI. This systematic review and meta-analysis sought to investigate the efficacy of PUFAs for promoting locomotor recovery in animal models of SCI. PubMed, Web of Science and Embase (Ovid) were searched for relevant papers and those that examined the restorative effects of PUFAs on locomotor recovery in preclinical SCI models were included in our analysis. A random effects meta-analysis (restricted maximum likelihood estimator) was employed. A total of 28 studies were included and the results showed the claim that PUFAs have a beneficial therapeutic effect for promoting locomotor recovery (SMD = 1.037, 95% CI = 0.809-1.2644, p = <0.001) and cell survival (SMD = 1.101, 95% CI = 0.889-1.313, p = <0.001) in animal models of SCI. No significant differences for the secondary outcomes of neuropathic pain and lesion volume. Moderate asymmetry was observed in the funnel plots for locomotor recovery, cell survival and neuropathic pain measures, suggesting publication bias. Trim-and-fill analysis estimated 13, 3, 0 and 4 missing studies for locomotor recovery, cell survival, neuropathic pain, and lesion volume, respectively. A modified CAMARADES checklist was also used to assess risk of bias, showing that the median score for all included papers was 4 out of a possible 7.

The Role of α-Linolenic Acid and Its Oxylipins in Human Cardiovascular Diseases

α-linolenic acid (ALA) is an essential C-18 n-3 polyunsaturated fatty acid (PUFA), which can be elongated to longer n-3 PUFAs, such as eicosapentaenoic acid (EPA). These long-chain n-3 PUFAs have anti-inflammatory and pro-resolution effects either directly or through their oxylipin metabolites. However, there is evidence that the conversion of ALA to the long-chain PUFAs is limited. On the other hand, there is evidence in humans that supplementation of ALA in the diet is associated with an improved lipid profile, a reduction in the inflammatory biomarker C-reactive protein (CRP) and a reduction in cardiovascular diseases (CVDs) and all-cause mortality. Studies investigating the cellular mechanism for these beneficial effects showed that ALA is metabolized to oxylipins through the Lipoxygenase (LOX), the Cyclooxygenase (COX) and the Cytochrome P450 (CYP450) pathways, leading to hydroperoxy-, epoxy-, mono- and dihydroxylated oxylipins. In several mouse and cell models, it has been shown that ALA and some of its oxylipins, including 9- and 13-hydroxy-octadecatrienoic acids (9-HOTrE and 13-HOTrE), have immunomodulating effects. Taken together, the current literature suggests a beneficial role for diets rich in ALA in human CVDs, however, it is not always clear whether the described effects are attributable to ALA, its oxylipins or other substances present in the supplemented diets.

Dietary Betaine Interacts with Very Long Chain n-3 Polyunsaturated Fatty Acids to Influence Fat Metabolism and Circulating Single Carbon Status in the Cat

Simple Summary

The domestic cat can metabolize and thrive on a range of intakes of different dietary polyunsaturated fatty acids (PUFA). However, changes in the intake of PUFA have relatively unknown effects on concentrations of other fatty acids and metabolites. Similarly, the effect of increasing dietary betaine (which is a single carbon donor) on circulating concentrations of metabolites and fatty acids is relatively unreported. As might be expected, increasing intake of specific dietary fatty acids resulted in an increased concentration of that fatty acid and moieties containing that fatty acid. Dietary betaine increased concentration of many compounds associated with single carbon metabolism (e.g., dimethyl glycine, sarcosine, methionine) and many PUFA such as the n-6 PUFA linoleic acid (LA) and arachidonic acid (ARA) and the n-3 fatty acids α-linolenic acid (αLA), and docosahexaenoic acid (DHA). Dietary betaine interacted with the addition of dietary fish oil to dampen diet-induced increase of ARA while potentiating the increase of circulating DHA occurring with increased DHA dietary intake. Dietary betaine and fish oil also combined to reduce the circulating concentration of the renal toxin 3-indoxyl sulfate, suggesting a positive effect on the gut microbiota. These data suggest a positive effect of a daily betaine intake which exceeds 60 mg per kg body weight. The data also support an added benefit of a combined EPA+DHA daily intake of greater than 26 mg/kg body weight as well as a daily intake of 75 mg/kg body weight of alpha linolenic acid.

Abstract

Six foods were used to evaluate the interaction of dietary betaine and n-3 PUFA in the cat. There was no ingredient added to the control food to specifically increase betaine or n-3 fatty acids. The experimental design was a 3 × 2 factorial (fatty acids were varied from the control food which had no added source of n-3 fatty acids, flax was included as a source of 18 carbon n-3, or menhaden fish oil as a source of EPA and DHA). Foods were then formulated using these three foods as a base with added betaine or without added betaine. Forty eight cats were used in this study. Equal numbers of cats were allotted by age and gender to each of the six dietary treatments. The cats were offered food amounts to maintain weight and consumed the food to which they were assigned for the length of the study (60 days). Metabolomics, selected circulating analytes and fatty acids were analyzed at the beginning and end of the feeding period. There was an increase in single carbon metabolites (betaine, dimethyl glycine, and methionine) with the consumption of dietary betaine. Betaine also increased the concentration of specific PUFA (ARA, αLA, DHA, and the sum of all circulating PUFA). The combination of dietary betaine and fish oil resulted in a reduction of circulating 3-indoxyl sulfate which suggests a renal benefit from their combined dietary presence.

Dietary Betaine and Fatty Acids Change Circulating Single-Carbon Metabolites and Fatty Acids in the Dog

In order to evaluate the interaction of betaine and n-3 PUFA in foods consumed by the dog, six extruded dry foods were formulated. The control food had no specific source of added betaine or n-3 fatty acids, while the test foods were supplemented with betaine, flax or fish oil in a 2 × 3 factorial design (no added n-3 source, added flax, added menhaden fish oil, and all with or without added betaine). Forty eight adult dogs were used in this study. All dogs were assigned to one of the six dietary treatments and consumed that food for the length of the 60-day study. Blood was analyzed for metabolomics (plasma), fatty acids and selected health-related analytes (serum) at the beginning and the end of the study. Added dietary betaine increased single-carbon metabolites (betaine, dimethyl glycine, methionine and N-methylalanine), decreased xenobiotics (stachydrine, N-acetyl-S-allyl-L-cysteine, 4-vinylguaiacol sulfate, pyrraline, 3-indoleglyoxylic acid, N-methylpipecolate and ectoine) and enhanced the production of eicosapentaenoic acid (EPA). Dietary betaine also decreased the concentration of circulating carnitine and a number of carnitine-containing moieties. The addition of the n-3 fatty acids alpha-linolenic, EPA and docosahexaenoic acid (DHA) increased their respective circulating concentrations as well as those of many subsequent moieties containing these fatty acids. The addition of alpha-linolenic acid increased the concentration of EPA when expressed as a ratio of EPA consumed.

Beneficial effect of long-chain n-3 polyunsaturated fatty acid supplementation on tuberculosis in mice

Intakes of the omega-3 essential fatty acids (n-3 EFAs) are low in the general adult population, with high n-6/n-3 polyunsaturated fatty acid (PUFA) ratios and the accompanying suboptimal n-3 PUFA status. Eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) have antibacterial and inflammation-resolving effects in tuberculosis (TB). However, whether switching to a diet with optimum n-3 EFA intake after the infection has comparable benefits has not been investigated. We aimed to compare the effects of a diet with sufficient n-3 EFA content in an acceptable n-6/n-3 PUFA ratio for rodents ((n-3)eFAS group) with those on the same diet supplemented with EPA and DHA (EPA/DHA group) in Mycobacterium tuberculosis (Mtb)-infected C3HeB/FeJ mice with a low n-3 PUFA status. Mice were conditioned on an n-3 PUFA-deficient diet with a high n-6/n-3 PUFA ratio for 6 weeks before Mtb infection and randomized to either (n-3)eFAS or EPA/DHA diets 1 week post-infection for 3 weeks. At endpoint, EPA and DHA compositions were higher and arachidonic acid, osbond acid, and total n-6 LCPUFAs lower in all lipid pools measured in the EPA/DHA group (all P < 0.001). Percentage body weight gain was higher (P = 0.017) and lung bacterial load lower (P < 0.001) in the EPA/DHA group. Additionally, the EPA/DHA group had a more pro-resolving lung lipid mediator profile and lower lung in IL-1α and IL-1β concentrations (P = 0.023, P = 0.049). Inverse correlations were found between the lung and peripheral blood mononuclear cell EPA and DHA and selected pro-inflammatory cytokines. These are the first findings that indicate that EPA/DHA supplementation provides benefits superior to a diet with sufficient n-3 EFAs concerning bacterial killing, weight gain and lung inflammation resolution in Mtb-infected mice with a low n-3 PUFA status. Therefore, EPA and DHA may be worth considering as adjunct TB treatment.

Modulatory Effect of Dietary Polyunsaturated Fatty Acids on Immunity, Represented by Phagocytic Activity

Lately, dietary polyunsaturated fatty acids (PUFAs) have shown substantial importance in human and animal nutrition, especially those of the n-3 group. Development and optimal functioning of the immune system are directed affected by diet. These dietary fatty acids have an important impact on the health and immune competence of various species including human beings. They are essential for the modulation of immune responses in health and disease. Fatty acid composition of immune cells can be modulated by the action of dietary fats and the outcomes in the composition can produce functional effects on reactivity and functioning of immune cells in a short period. There are several mechanisms involved in impacting dietary fatty acids on immune function; however, lipid mediator synthesis from PUFAs is of great importance in terms of inflammation. The objectives of this article are reviewing studies on the impact of PUFA in the diet on phagocytosis of chickens, murine, rats, ruminants, and humans. It also sheds light on the possible mechanism by which this immunomodulation occurs.

Diet Supplemented with Chia Flour did not Modified the Inflammatory Process and Tumor Development in Wistar Rats Inoculated with Walker 256 Cells

Chia seed (Salvia hispanica L.) contains high amounts of n-3 α-linolenic acid (ALA) and has been associated with many health benefits. The aim of the present study was to evaluate the AIN-93 diet supplemented by chia flour on cancer-cachexia development and tissues inflammatory response. Wistar rats at 30 days old were treated with control diet or diet supplemented with chia flour for eight weeks. After this period, half of the animals in each diet group were inoculated with Walker 256 tumor cells. On the 14th day after tumor inoculation, the animals were euthanized and white adipose tissue depots, liver, gastrocnemius muscle, and tumor were removed. The tumor weight was higher and IL-10 content was lower in chia flour group. The tumor bearing did not modify the cytokines content in gastrocnemius muscle, retroperitoneal and epididymal adipose tissue, however, it decreased IL-1β and TNF-α content in liver, and IL6R and IL-10R protein content in mesenteric adipose tissue. In conclusion, our results demonstrated that supplementation with chia flour did not prevent the tumor bearing effects in Walker 256 model.

Barriers to cancer nutrition therapy: excess catabolism of muscle and adipose tissues induced by tumour products and chemotherapy

Cancer-associated malnutrition is driven by reduced dietary intake and by underlying metabolic changes (such as inflammation, anabolic resistance, proteolysis, lipolysis and futile cycling) induced by the tumour and activated immune cells. Cytotoxic and targeted chemotherapies also elicit proteolysis and lipolysis at the tissue level. In this review, we summarise specific mediators and chemotherapy effects that provoke excess proteolysis in muscle and excess lipolysis in adipose tissue. A nutritionally relevant question is whether and to what degree these catabolic changes can be reversed by nutritional therapy. In skeletal muscle, tumour factors and chemotherapy drugs activate intracellular signals that result in the suppression of protein synthesis and activation of a transcriptional programme leading to autophagy and degradation of myofibrillar proteins. Cancer nutrition therapy is intended to ensure adequate provision of energy fuels and a complete repertoire of biosynthetic building blocks. There is some promising evidence that cancer- and chemotherapy-associated metabolic alterations may also be corrected by certain individual nutrients. The amino acids leucine and arginine provided in the diet at least partially reverse anabolic suppression in muscle, while n-3 PUFA inhibit the transcriptional activation of muscle catabolism. Optimal conditions for exploiting these anabolic and anti-catabolic effects are currently under study, with the overall aim of net improvements in muscle mass, functionality, performance status and treatment tolerance.

Dietary supplementation of α-linolenic acid induced conversion of n-3 LCPUFAs and reduced prostate cancer growth in a mouse model

Background

α-linolenic acid (ALA) is an n-3 polyunsaturated fatty acid (PUFA) and the substrate for long-chain n-3 PUFAs. The beneficial effects of ALA on chronic diseases are still in dispute, unlike those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Methods

The primary objective of this investigation was to evaluate the efficiency of ALA uptake from a vegetable oil source and its subsequent conversion to n-3 long-chain PUFAs (LCPUFAs) in the tissues of growing mice, and to investigate its protective role in a prostate cancer animal model. We carried out the investigation in prostate-specific Pten-knockout mice with specified low-ALA (L-ALA, 2.5%) and high-ALA (H-ALA, 7.5%) diets. Total fatty acids in blood, liver, epididymal fat pad, prostate were detected and prostate weight were adjusted for body weight (mg/25 g).

Results

We found that dietary ALA triggered significant increases in ALA, EPA, docosapentaenoic acid (DPA) and DHA levels and a significant decrease in arachidonic acid levels during the mice’s growth stage. A dose-dependent effect was observed for ALA, EPA and DPA, but not DHA. Furthermore, the average prostate weights in the L-ALA and H-ALA groups were lower than those in the control and n-6 groups, and similar to those in the EPA and n-3 groups.

Conclusions

Our data suggest that dietary supplementation with ALA is an efficient means of improving n-3 LCPUFAs in vivo, and it has a biologically effective role to play in prostate cancer, similar to that of fish oils.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0529-z) contains supplementary material, which is available to authorized users.