DHA Diets Research Articles

Blood and tissue docosahexaenoic acid (DHA, 22:6n-3) turnover rates from Ahiflower® oil are not different than from DHA ethyl ester oil in a diet switch mouse model

Ahiflower® oil is high in α-linolenic and stearidonic acids, however, tissue/blood docosahexaenoic acid (DHA, 22:6n-3) turnover from dietary Ahiflower oil has not been investigated. In this study, we use compound-specific isotope analysis to determine tissue DHA synthesis/turnover from Ahiflower, flaxseed and DHA oils. Pregnant BALB/c mice (13–17 days) were placed on a 2 % algal DHA oil diet of high carbon-13 content (δ13C) and pups (n = 132) were maintained on the diet until 9 weeks old. Mice were then randomly allocated to a low δ13C-n-3 PUFA diet of either: 1) 4 % Ahiflower oil, 2) 4.35 % flaxseed oil or 3) 1 % fish DHA ethyl ester oil for 1, 3, 7, 14, 30, 60 or 120 days (n = 6). Serum, liver, adipose and brains were collected and DHA levels and δ13C were determined. DHA concentrations were highest (p < 0.05) in the liver and adipose of DHA-fed animals with no diet differences in serum or brain (p > 0.05). Based on the presence or absence of overlapping 95 % C.I.'s, DHA half-lives and synthesis/turnover rates were not different between Ahiflower and DHA diets in the liver, adipose or brain. DHA half-lives and synthesis/turnover rates from flaxseed oil were significantly slower than from the DHA diet in all serum/tissues. These findings suggest that the distinct Ahiflower oil n-3 PUFA composition could support tissue DHA needs at a similar rate to dietary DHA, making it a unique plant-based dietary option for maintaining DHA turnover comparably to dietary DHA.

Effects of dietary ARA, DHA, and carbohydrates levels on gilthead sea bream liver and intestine oxidative stress, tissue histomorphology, and gut microbiota

The present study aims evaluate the oxidative status, histomorphology of liver and intestine, and intestinal microbiota modulation of gilthead sea bream juveniles (initial body weight = 47.5 g) fed four isoproteic and isolipidic diets (47% protein; 18% lipids) with high or low gelatinized starch levels (20% or 5%; diets HS or LS, respectively) and different dietary ARA or DHA content (2.3/0.3 or 0/2.6, diets ARA or DHA, respectively).ARA-rich diets reduced liver and intestine lipid peroxidation (LPO) circa 12 and 66%, respectively. Dietary ARA also increased liver glutathione redox status (total, reduced (GSH) and oxidized glutathione (GSSG)) circa of 35% but only in the HS diets. Independently of dietary starch level, dietary ARA also reduced GSSG content (80 and 63 nmol g−1 tissue) and oxidative stress index (OSI) (8.7 and 7%) in the intestine. Fish fed DHA diets had increased hepatic superoxide dismutase (SOD) (749.1 and 489.1 U mg protein−1) and glutathione reductase (GR) (3.7 to 1.9 mU mg protein−1) activities. In the intestine, dietary ARA or DHA did not induce alterations in the activity of the antioxidant enzymes. Dietary starch improved liver OSI (1.5%), increased intestinal GSSG (80 and 128 nmol g−1 tissue), and decreased intestinal LPO values (104 nmol MDA g−1 tissue) in fish fed the DHA diets. Fish fed the HS diets had increased hepatic glucose-6-phosphate dehydrogenase (G6PDH) (171.4 and 166 mU mg protein−1), GR (2 and 3.71 mU mg protein−1), and glutathione peroxidase (GPX, only in DHA diets) (63.8 mU mg protein−1) activities, but decreased GR (27.2 and 27.6 mU mg protein−1) and SOD (2089.7 and 2158.8 U mg protein−1) activities in the intestine.Diet composition did not induce major histomorphological alterations in the distal intestine. Nevertheless, the HS diets, especially when combined with DHA, promoted hepatocyte hypertrophy and alterations in nuclei position.Compared to the DHA diets, in fish fed the ARA diets, mucosa bacterial profile had a reduced number of operational taxonomic units (10.3 and 12.0), richness (0.6 and 0.7), and diversity (2.2 and 2.3), and higher similarity between bacterial communities (85.0 and 80.4%).In conclusion, fish fed high dietary ARA presented lower hepatic and intestinal LPO and fewer hepatocyte morphological alterations than fish fed high DHA diets. Furthermore, interactive effects between dietary starch and DHA on liver and intestine GSH metabolism, antioxidant enzymes, LPO susceptibility, and liver histomorphology may be attenuated by a balanced ARA/DHA dietary ratio.

Synbiotic Combination of Djulis (Chenopodium formosanum) and Lactobacillus acidophilus Inhibits Colon Carcinogenesis in Rats.

Djulis is a functional grain containing prebiotic dietary fiber, which has an anti-cancer potential. This study examined the preventive effect of djulis alone or in combination with Lactobacillus acidophilus on colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS). Rats were divided into five groups and fed B (AIN-93G, blank), C (AIN-93G, control), D (10% djulis), DLA (10% djulis plus 5 × 106 cfu L. acidophilus/g), and DHA (10% djulis plus 5 × 107 cfu L. acidophilus/g) diets, respectively. All rats except for those in group B received three doses of DMH (40 mg/kg) by intraperitoneal injection and 3% DSS in drinking water. After 10 weeks of feeding, the colon was analyzed for precancerous lesions and biomarkers. DMH and DSS treatment induced aberrant crypt foci (ACF), especially in the distal colon. D, DLA, and DHA significantly reduced the numbers of total ACF, sialomucin-producing ACF (SIM-ACF), and mucin-depleted foci (MDF) in the distal colon compared to C. Additionally, DLA and DHA further downregulated the expressions of proliferating cell nuclear antigen (PCNA) and cyclooxygenase-2 (COX-2) and regulated apoptosis-related proteins. These results suggest that synbiotic combination of djulis and L. acidophilus shows the best inhibitory effect on colon carcinogenesis via regulation of proliferative, inflammatory, and apoptotic pathways.

Docosahexaenoic acid (22:6n-3) Ameliorated the Onset and Severity of Experimental Autoimmune Encephalomyelitis in Mice.

Multiple sclerosis (MS) is a neurologic autoimmune disease, which is the leading cause of nontraumatic neurologic disability in young adults in United States and Europe. n-3 polyunsaturated fatty acids (PUFA) are reported to mitigate severity of this disease. Recent studies suggest that phospholipid (PL) form of dietary n-3 PUFA may lead to their higher tissue accretion than triacylglycerol (TAG) form. We compared efficacy of PL-docosahexaenoic acid (22:6n-3) (DHA) and TAG-DHA on onset and severity of experimental autoimmune encephalomyelitis (EAE) in a mouse model of MS. Female mice were fed low alpha-linolenic acid (18:3n-3) (ALA) diet (control) for 2 weeks and then fed either control, 0.3%, or 1.0% DHA (PL or TAG) for 4 weeks pre-EAE induction and 4 weeks post-EAE induction. The brain and spinal cord n-6:n-3 ratio was significantly lower in all mice fed DHA compared to control. EAE onset was delayed in mice fed both DHA forms and concentrations, except for 1% TAG-DHA. The inverse association between the EAE score and the brain DHA concentration was nonsignificant at the end of the study (p = 0.08). Daily EAE scores of mice fed different DHA diets did not differ from control, however, the score of all DHA groups combined during days 9-16 was lower (p = 0.028) compared to the control. During days 17-22, the EAE score trended lower in 0.3% TAG-DHA and during days 23-28, the EAE score trended lower in both PL-DHA groups than those in all other groups. These findings suggest that TAG-DHA may be more effective than PL-DHA in the early phases of EAE, and in the final outcome, PL-DHA may be more effective than TAG-DHA.

Low Sucrose, Omega-3 Enriched Diet Has Region-Specific Effects on Neuroinflammation and Synaptic Function Markers in a Mouse Model of Doxorubicin-Based Chemotherapy.

Chemotherapeutic agents such as doxorubicin may negatively affect long-term brain functioning in cancer survivors; neuroinflammation may play a causal role. Dietary approaches that reduce inflammation, such as lowering sucrose and increasing eicosapentaenoic acid plus docosahexaenoic acid (EPA + DHA), may attenuate chemotherapy-induced neuroinflammation and synaptic damage, thereby improving quality of life. Ovariectomized, C57BL/6 mice were assigned to a chemotherapy (9 mg/kg doxorubicin + 90 mg/kg cyclophosphamide) or vehicle two-injection regimen, with injections two and four weeks after starting diets. In Study 1, mice received low sucrose diets with EPA + DHA or No EPA + DHA for four to six weeks; tissues were collected four, seven, or 14 days after the second injection. Compared to vehicle, chemotherapy increased pro-inflammatory cytokine IL-1β at day seven in the cortex and hippocampus, and reduced gene expression of synaptic marker Shank 3 at all timepoints in cortex, while EPA + DHA increased expression of Shank 3. In Study 2, high or low sucrose/EPA + DHA or No EPA + DHA diets were fed for five weeks; tissues were collected ten days after the second injection. Among chemotherapy-treated mice, brain DHA was higher with low sucrose feeding. Furthermore, low sucrose increased gene expression of Shank 1, while EPA + DHA increased expression of Shank 3 and reduced protein concentrations of pro-inflammatory markers IL-5, IL-6 and KC/GRO in the cortex, but not the hippocampus. Low sucrose, EPA + DHA diets may attenuate neuroinflammation and synaptic damage induced by doxorubicin-based chemotherapy in specific brain regions.

The effect of dietary DHA and taurine on rotifer capture success, growth, survival and vision in the larvae of Atlantic bluefin tuna (Thunnus thynnus)

The severe to complete mortality that occurs during the larviculture of Atlantic bluefin tuna (ABFT; Thunnus thynnus) may be due, in part, to sub-optimal neural and eye development. The adult and larval ABFT eyes are rich in docosahexaenoic acid (DHA; 22:6n-3), which facilitates key intra-membrane reactions in the photoreceptors of the retina. Another critical nutrient is taurine, which plays vital roles that include bile salt conjugation as well as development and function of visual, neural and muscular systems. The objectives of the present study were to (1) determine the pattern of conservation and loss of fatty acid groups and their constituent fatty acids during egg and pre-larval development as well as in food deprivation. (2) Determine the effect of rotifer (Brachionus rotundiformis) DHA on hunting success, growth, and retinal opsin abundance in 2–14dph ABFT larvae. (3) Evaluate the effect of supplemented taurine in rotifers enriched on the most effective DHA level from objective (2) on larval survival and growth.During the egg and yolk sac larval stages, there was a significant decrease (P<0.05) in SAT, MONO and PUFA that can be expressed as 46.7%, 50.3% and 57.1%, respectively. Similarly, the levels of DHA, EPA, and ArA were markedly (P<0.05) reduced that can be expressed as 59.8%, 52.5% and 59.5%, respectively. In the DHA study, there was a rotifer DHA dose dependent (P<0.05) effect on prey consumption by 3–7dph ABFT larvae where the highest DHA level (11mgg−1 DW rotifer) elicited significantly (P<0.05) higher rotifer consumption compared to the control and moderate DHA diets (2mgg−1 DW and 5mgg−1 DW rotifer, respectively). Moreover, larvae with the highest DHA level (7.01mgg−1 DW) exhibited a significantly (P<0.05) higher opsin protein concentration (25.27 unit area−1) compared to the 2.83mgDHAg−1 DW and 1.26mgDHAg−1 DW fish (20.32 and 16.33 opsin protein unit area−1, respectively). Although there was a significant (P<0.05) taurine modulated increase in larval length in 10dph fish, there was a non-significant (P>0.05) growth advantage, in terms of dry weight, as a result of moderate dietary taurine supplementation at the end of the study. Nevertheless, the moderate 6.44mgtaurineg−1 DW larvae exhibited markedly (P=0.024) better survival and >4 times higher (P=0.0018) average tank biomass (273.6mg) than the low (1.97mgg−1 DW) and high (12.62mgg−1 DW) taurine fish (62.14 and 56.90mg, respectively). Overall, the data suggests that supplementing effective levels of DHA and taurine contributes to an array of physiological processes resulting in enhanced vision and prey acquisition to markedly improve ABFT larval performance during early development.

Can Senegalese sole post-larvae effectively grow on low dietary DHA and lipid levels during weaning?

Senegalese sole (Solea senegalensis) is a highly-valuable flatfish species with interest for diversification of aquaculture in Mediterranean countries. Unlike other fish species known to have a high dietary DHA requirement during the larval stage, several studies have suggested dietary DHA could play a minor role for Senegalese sole during the early developmental stages. This suggestion was recently supported by studies that indicated an ability of Senegalese sole to biosynthesise DHA from its precursors during the larval period. However, it is still uncertain if Senegalese sole post-larvae can effectively grow on low dietary DHA levels during weaning. Moreover, recent studies focusing on the juvenile phase of Senegalese sole have suggested a possible impairment of this species to efficiently digest or absorb high dietary lipid levels. Yet, if a reduction of dietary lipid levels would affect a normal development of Senegalese sole during the early stages remains to be established. Therefore, this study aimed at determining if a reduction of dietary DHA and lipid levels would affect Senegalese sole performance and lipid metabolism during weaning and post-larval period. In this study, Senegalese sole post-larvae were reared according to four dietary treatments: low lipid levels (treatments LFAT and LFAT_DHA) and moderate lipid levels (MODFAT and MODFAT_DHA). DHA levels in LFAT_DHA and MODFAT_DHA diets were higher than in LFAT and MODFAT diets, respectively. Subsequently, effects of experimental diets on Senegalese sole post-larval growth, survival, fatty acid composition and histopathological condition of intestinal and liver tissues were evaluated. Results showed that feeding on diets with low DHA and lipid levels significantly reduced the growth performance of Senegalese sole post-larvae. However, at the end of the experimental period, no significant differences were observed for post-larval survival in response to dietary treatments. In overall, this study disadvises that weaning diets for Senegalese sole post-larvae should contain low DHA and lipid levels, as a reduction of these levels may compromise post-larval growth performance. Statement of relevanceDetermining essential fatty acid requirements in marine fish larvae is of utmost importance for the aquaculture industry, contributing to fulfil the growth potential of farmed species. In the case of Senegalese sole, a highly valued species farmed in Mediterranean countries, it may have the capacity to biosynthesise DHA from its precursors during the larval stage. However, the inclusion of DHA-rich oils in weaning diets is costly, considerable savings could be achieved by replacing DHA-rich oils by common fish oils in weaning diets for this species. Furthermore, Senegalese sole has also been shown a poor ability to deal with high dietary lipid levels during the juvenile stage. However, no studies have addressed this capacity in Senegalese sole larvae. This study comprises an evaluation on the effects of reducing dietary DHA and lipid levels during Senegalese sole weaning by integrating an assessment of these effects on post-larval growth, survival, fatty acid composition and histopathological condition.

DHA-Rich Tuna Oil Effectively Suppresses Allergic Symptoms in Mice Allergic to Whey or Peanut

Background: Supplementation with long-chain n–3 polyunsaturated fatty acids (LCPUFAs) has been found to reduce the development of allergic disease.Objective: The aim of this study was to compare the effectiveness of fish oil diets rich in eicosapentaenoic acid (20:5n–3; EPA) or docosahexaenoic acid (22:6n–3; DHA) in suppressing food allergic symptoms.Methods: Mice were fed a control diet (10% soybean oil) or fish oil diet rich in EPA (4% soybean oil + 6% EPA oil containing 28.8% EPA and 13.7% DHA) or DHA (4% soybean oil + 6% DHA oil containing 7% EPA and 27.8% DHA), starting 14 d before and for 5 wk during oral sensitization with peanut extract (PE) or whey. Acute allergic skin responses, serum immunoglobulins (Igs), and mucosal mast cell protease-1 (mmcp-1) were assessed. Hyperimmune serum was transferred to naive recipient mice fed the different diets.Results: The DHA diet effectively reduced the acute allergic skin response compared with the control or EPA diet in PE-allergic mice (control, 159 ± 15, or EPA, 129 ± 8, vs. DHA, 78 ± 7 μm; P < 0.0001 or P < 0.05, respectively). In contrast, both the DHA and EPA diets reduced the allergic skin response in whey allergic mice (control, 169 ± 9, vs. DHA, 91 ± 13, or EPA, 106 ± 14 μm; P < 0.001 or P < 0.01, respectively); however, only the DHA diet reduced mmcp-1 and whey-specific IgE and IgG1. The DHA and EPA diets also reduced the acute skin response in passively immunized mice.Conclusions: The DHA-rich fish oil diet reduced allergic sensitization to whey and allergic symptoms in both PE- and whey-allergic mice. These data suggest that DHA-rich fish oil is useful as an intervention to prevent or treat food allergy symptoms.

Dietary saturated fat and docosahexaenoic acid differentially effect cardiac mitochondrial phospholipid fatty acyl composition and Ca2+uptake, without altering permeability transition or left ventricular function

High saturated fat diets improve cardiac function and survival in rodent models of heart failure, which may be mediated by changes in mitochondrial function. Dietary supplementation with the n3-polyunsaturated fatty acid docosahexaenoic acid (DHA, 22:6n3) is also beneficial in heart failure and can affect mitochondrial function. Saturated fatty acids and DHA likely have opposing effects on mitochondrial phospholipid fatty acyl side chain composition and mitochondrial membrane function, though a direct comparison has not been previously reported. We fed healthy adult rats a standard low-fat diet (11% of energy intake from fat), a low-fat diet supplemented with DHA (2.3% of energy intake) or a high-fat diet comprised of long chain saturated fatty acids (45% fat) for 6 weeks. There were no differences among the three diets in cardiac mass or function, mitochondrial respiration, or Ca2+-induced mitochondrial permeability transition. On the other hand, there were dramatic differences in mitochondrial phospholipid fatty acyl side chains. Dietary supplementation with DHA increased DHA from 7% to ∼25% of total phospholipid fatty acids in mitochondrial membranes, and caused a proportional depletion of arachidonic acid (20:4n6). The saturated fat diet increased saturated fat and DHA in mitochondria and decreased linoleate (18:2n6), which corresponded to a decrease in Ca2+ uptake by isolated mitochondria compared to the other diet groups. In conclusion, despite dramatic changes in mitochondrial phospholipid fatty acyl side chain composition by both the DHA and high saturated fat diets, there were no effects on mitochondrial respiration, permeability transition, or cardiac function.

The Effects of Diets Containing Standard Soybean Oil, Soybean Oil Enhanced with Conjugated Linoleic Acids, Menhaden Fish Oil, or an Algal Docosahexaenoic Acid Supplement on Channel Catfish Performance, Body Composition, Sensory Evaluation, and Storage Characteristics

AbstractFish consumption is a common method of obtaining beneficial n‐3 highly unsaturated fatty acids (LC‐PUFAs), but increased use of vegetable oils in fish diets to reduce dependence on fish oil dilutes the amounts of LC‐PUFAs. Conjugated linoleic acids (CLAs) are also considered beneficial for human health. Therefore, we investigated four different lipid sources in Channel Catfish Ictalurus punctatus diets for their ability to enhance fatty acid profiles of fillets to benefit human health while maintaining or improving fish performance. In a 175‐d grow‐out trial, Channel Catfish (71.4 ± 0.1 g [mean ± SE]) were fed a commercial 32% protein diet supplemented with 2% lipid from soybean oil (SO), soybean oil enhanced with conjugated linoleic acids, menhaden fish oil (FO), or an algal supplement of Schizochytrium sp. high in 22:6(n‐3) (docosahexaenoic acid, DHA). Diet effects were assessed by measuring fish growth performance, muscle proximate and fatty acid composition, sensory characteristics of fillets, consumer taste preferences, and oxidative stability of fillets during cold storage. There were no differences in fish growth performance or proximate composition. Only fish fed the CLA diet contained CLAs in the muscle. Fish fed the FO and algal DHA diets had higher concentrations of 22:6(n‐3) in the muscle compared with fish fed the SO and CLA diets. Sensory evaluation and consumer preference testing were more favorable for fillets from fish fed the SO and CLA diets than from fish fed the FO and algal DHA diets. There were no differences in storage characteristics of fish refrigerated at 4°C for 2 weeks or frozen at −18°C for 4 weeks. Fillets from fish fed the FO diet yielded the highest concentration of fatty acids for human health benefits, followed by the fillets from fish fed the algal DHA diets. The CLA diet produced increased fillet concentrations of CLAs.

Long-term supplementation of dietary omega-6/omega-3 ratios alters bone marrow fatty acid and biomarkers of bone metabolism in growing rabbits

The long-term effects of different dietary lipid sources with varying ratios of omega-6/omega-3 (ω6/ω3) polyunsaturated fatty acids (PUFAs) on the bone marrow fatty acid profile, ex vivo prostaglandin E2 (PGE2) release in bone, and plasma biomarkers of bone metabolism were evaluated in rabbits. Weanling male and female New Zealand white rabbits were randomly assigned to five groups and fed ad libitum on diets containing 70g/kg of added oil for 100days as follow: soy bean oil (SBO control), sesame oil (SO), fish oil (FO), DHA algae oil (DHA), and DHA and ARA algae oils (DHA/ARA). The dietary lipid treatments were formulated to provide the following ratios of ω6/ω3 fatty acids: 8.7 (SBO), 21.8 (SO), 0.4 (FO), 0.6 (DHA), and 0.7 (DHA/ARA). The bone marrow fatty acid profile of rabbits was significantly influenced by and reflected the dietary lipid treatments. Rabbits fed the FO diet had the highest ω3 PUFA concentration, and those fed the SBO diet were highest in ω6 PUFA. Ex vivo PGE2 level declined progressively as the ω6/ω3 dietary ratio declined. Plasma alkaline phosphatase (ALP) activity was significantly higher in male and female rabbits fed the DHA/ARA diet compared with those fed the control, SO, FO, or DHA diets. These results demonstrated that the dietary ω6/ω3 ratio modulates bone PGE2 production and plasma ALP activity in growing rabbits. In addition, the significant elevation in ALP activity in the DHA/ARA fed group proved that algae oils may be promising dietary sources for promoting bone formation during the growing stage.

Dietary Supplementation with Docosahexanoic Acid or Arachidonic Acid Delay Ca2+ ‐Induced Permeability Transition Pore Opening in Cardiac Mitochondria

Supplementation with docosahexanoic acid (DHA, commonly found in fish oil) in clinically relevant amounts causes a 2-fold increase in DHA in cardiac phospholipids, and delays Ca2+-induced mitochondrial permeability transition pore (MPTP) opening. The mechanism for this effect is not clear, however the increase in DHA is accompanied by a decrease in the ù-6 PUFA arachidonic acid (ARA), which could be responsible for the effects on the MPTP. We determined the role of ARA on MPTP opening by feeding rats DHA, ARA or DHA+ARA. Male Wistar rats were fed either a los DHA+AHA diet(CTRL), a diet containing DHA or ARA at 2.5% of energy intake, or both DHA and ARA at 2.5% each, for 10 wks. Cardiac mitochondria were isolated. All three diets profoundly altered the phospholipid composition of mitochondria compared to CTRL. Both the DHA and ARA groups delayed Ca2+-induced MPTP opening vs. CTRL (p<0.05) while DHA+ARA increased sensitivity to MPTP opening (p<0.05 vs CTRL, DHA or ARA). Furthermore, both diets containing ARA significantly increased the pro-inflammatory marker TBX B2 by 2- to 3-fold compared to CTRL and DHA diets (p<0.05). DHA+ARA also increased lipid peroxidation compared to ARA alone (p=0.008) and to CTRL (p=0.034). This suggests that the effect of DHA on MPTP is not due to depletion of ARA. DHA+ARA showed no added benefit, but rather sensitized MPTP to opening, suggesting that a very large dose of PUFA might be detrimental.

DHA status of vegetarians

Background Docosahexaenoic acid (22:6n-3; DHA) is absent from vegan diets and present in limited amounts in vegetarian diets. Objective To review DHA status in vegetarians and vegans. Design To identify published studies and review their findings. Results Dietary analyses show that vegan diets are devoid of DHA and vegetarian diets that included dairy food and eggs only provide about 0.02 g DHA/d. Vegetarian and especially vegan diets supply more linoleic acid (18:2n-6) than omnivore diets. The intake of α-linolenic acid (18:3n-3) also tends to be similar or greater but depends on culinary oils used. The proportions of DHA in plasma, blood cells, breast milk, and tissues are substantially lower in vegans and vegetarians compared with omnivores. The lower proportions of DHA are accompanied by correspondingly higher proportions of the long-chain derivatives of linoleic acid, indicating that the capacity to synthesize long-chain polyunsaturated fatty acids is not limited. Short-term dietary supplementation with α-linolenic acid increases the proportion of eicosapentaenoic acid (20:5n-3) but does not increase the proportion of DHA in blood lipids. Small amounts of preformed DHA (as low as 200 mg) result in a large increase in the proportion of DHA in blood lipids in vegetarians and vegans. There is no evidence of adverse effects on health or cognitive function with lower DHA intake in vegetarians. Conclusions Preformed DHA in the diet of omnivores explains the relatively higher proportion of this fatty acid in blood and tissue lipids compared with vegetarians. The pathophysiological significance of this difference remains to be determined.

Enhanced lumbar spine bone mineral content in piglets fed arachidonic acid and docosahexaenoic acid is modulated by severity of growth restriction

The infant born small size for gestational age (SGA) has low bone mass. Since dietary arachidonic acid (AA) and DHA enhance bone mass in normal-birth-weight piglets the objective of the present study was to test for such benefits in the SGA piglet. In the present 15 d study, two levels of dietary AA and DHA (6:1 ratio of AA:DHA diets, 0.6:0.1 or 1.2:0.2 g/100 g dietary fat) v. a control diet were tested for effects on growth, fatty acid status, whole-body and regional bone mineral content (BMC) and metabolism in SGA piglets categorised as either very low birth weight (VLBW; < or = 1.0 kg; n 12) or low birth weight (LBW; 1.1 to 1.2 kg; n 18). Differences in outcomes for each body weight category were detected using ANOVA with post hoc Bonferroni tests. Growth was not influenced by diet, yet the LBW piglets fed 0.6:0.1 AA and DHA as g/100 g fat had elevated BMC in the spine, whereas the VLBW piglets had higher BMC of the spine if fed the higher intake of AA and DHA. In both weight categories, the higher intake of AA and DHA lowered bone resorption relative to controls, whereas bone formation was unchanged. Tissue fatty acid concentrations reflected dietary AA and DHA, especially trabecular bone of VLBW piglets. Whether the enhanced lumbar spine BMC is due to enhanced Ca absorption and thus suppression of bone resorption remains to be established.

Effect of dietary docosahexaenoic acid and phosphatidylcholine on maze behavior and fatty acid composition of plasma and brain lipids in mice.

We investigated the effects of dietary docosahexaenoic acid (DHA, 22:6 n-3) and phosphatidylcholine (PC) on maze behavior and brain fatty acids in mice. Male Crj:CD-1 mice (3 wk old) were fed a diet containing 2% DHA and 3% palm oil (DHA group); 5% PC (PC group); 1% DHA, 2.5% PC and 1.5% palm oil (DHA + PC group); 5% palm oil (Palm oil control group) or MF laboratory chow (MF control group) for 7 mo. After this time maze-learning ability was assessed. The time required to reach the maze exit and the number of times that a mouse strayed into blind alleys in the maze were measured three times every four days. After the last learning test, all mice were sacrificed and plasma and brain were analyzed for fatty acid composition. The DHA and PC groups required less time to reach the maze exit and strayed less into blind alleys than the control group in the third trial. The difference between the DHA or PC groups and control mice was statistically significant (p < 0.05). In the total lipids of plasma and brain of mice fed DHA, there was a significant increase in DHA levels and a concomitant decrease in arachidonic acid (AA, 20:4 n-6). Similar changes in fatty acid composition were observed in brain phosphatidylcholine and phosphatidylethanolamine for this group of mice. However, this pattern of changes in brain fatty acids was not evident in the PC group. Our data suggest that maze-learning ability in mice is enhanced by intakes of DHA and PC. However, the mechanisms by which the DHA and PC diets improved learning ability appear to be different. A synergistic effect of DHA and PC on learning ability is not apparent in the DHA + PC group.

Dietary Docosahexanoic Acid (DHA) Effects upon the Rat Pup Auditory System• 1526

Rats fed diets high in n3 fatty acids have lower whole brain levels of myelin basic protein, lower activities of 2′-3′cyclic nucleotide 3′-phosphodiesterase(an indicator of myelination) (DiBiase & Salvati, 1997), and longer auditory brainstem conduction times (ABCTs) (Saste et al., in press). We investigated the effects of varying levels of the n3 fatty acid DHA upon development of the rat pup auditory system.Methods: Dams were fed, from day 2 of gestation and throughout lactation, a purified diet whose fat source (22% of cals) was a vegetable oil blend supplemented with an algae oil containing 0% or 3% DHA. On postnatal day(pnd) 3, pups were culled to 10 per dam and were randomly cross fostered among dams of the same diet group to minimize litter effects (n=6 dams per diet group, 60 pups per diet group). Milk from culled pup stomachs was used for fatty acid analysis. On pnd 15, auditory electromyelographic reflexes (AEMR) to 130 db peak sound pressure level clicks were recorded from needle electrodes placed in the muscle of the thigh of 20 pups per diet group; pups were then sacrificed and brainstems removed for fatty acid analysis. For the remaining 40 pups per diet group, ABCTs were measured on pnd 24 and 31, and the postnatal day of appearance of the auditory startle reflex was determined. An additional group of dams fed 1% DHA diet had pups whose weight gains were 2/3 that of dams fed the 0% or 3% DHA diets; data from these pups are not presented. Results: Length of gestation, maternal weight gains and pup weights on pnd 3 did not differ between diet groups. Weight gains to pnd 12 were slightly lower among pups of dams fed the 3% DHA diet. The fatty acid composition of dam milk and pup brainstems reflected maternal diet. AEMRs were not different, however, ABCTs on pnd 24 were longer and the time of appearance of the auditory startle reflex was later in pups of dams fed 3% DHA.Conclusion: High levels of dietary DHA during development may be associated with delays in myelination of the central nervous system as suggested by longer ABCTs and a delay in appearance of the auditory startle reflex. Similar AEMRs between diet groups suggest minimal effects upon the peripheral nervous system. Table