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Dietary intakes vary with age among Eskimo adults of Northwest Alaska in the GOCADAN study, 2000-2003

Dietary factors influence the development of cardiovascular disease (CVD). The diet of Alaskan Eskimos differs from that of other populations. We surveyed Eskimo adults in Northwest Alaska to document their usual dietary intakes, differences based on gender and age, and sources of selected nutrients, and to generate appropriate dietary advice to reduce CVD. Interviewers surveyed 850 men and women 17-92 y old, using a quantitative food-frequency instrument. We observed many significant (chi(2) analysis P < 0.05) differences in nutrient intakes among 3 age-groups. Energy intake from carbohydrate was negatively related to participant age-group (P < or = 0.01). Energy intake from all fats (P < 0.001) and polyunsaturated fat (P < or = 0.01) was positively related to age-group among both men and women in contrast to other studies in which age differences were either not observed or decreased with age.

Native foods were major sources of monounsaturated and polyunsaturated fats, including 56% of (n-3) fatty acids primarily from seal oil and salmon. However, Native foods contributed significantly less to the diets of young adults than to those of elders, especially among women. Store-bought foods were the main sources of energy, carbohydrate, fat, saturated fat, and fiber for all adults. Based on their nutrient density and potential to inhibit CVD, continued consumption of traditional foods is recommended. Variations in intake by age may portend changing eating patterns that will influence CVD as participants age. These data will contribute to understanding dietary risk factors for cardiovascular disease in this population.

Effect of supplementation with dietary seal oil on selected cardiovascular risk factors and hemostatic variables in healthy male subjects.

Department of Human Biology, University of Guelph, Ontario, Canada. The average daily consumption of seal oil by the Inuit people is approximately 8-9 g, yet there is very little information on the effect of seal oil consumption on cardiovascular disease risk factors. In this study, 19 healthy, normocholesterolemic subjects consumed 20 g of encapsulated seal oil containing eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3), and docosapentaenoic acid (DPA; 22:5n-3) or 20 g of vegetable oil (control) per day for 42 days. Levels of selected cardiovascular and thrombotic risk factors as well as fatty acid profiles of serum phospholipid and nonesterified fatty acid (NEFA) were determined.

EPA levels in serum phospholipid and NEFA increased by 4.3- and 2.7-fold, respectively, in the seal oil supplemented group. DHA levels rose 1.5- and 2.1-fold, respectively, and DPA levels rose 0.5- and 0.7-fold, respectively. Arachidonic acid (AA) levels dropped by 26% in both serum phospholipid and serum NEFA. There was a significant decrease in the ratio of n-6 to n-3 fatty acids in serum phospholipid from 7.2 to 2.1 and a significant increase in the ratio of EPA/AA in NEFA. Ingestion of seal oil raised the coagulant inhibitor, protein C, values by 7% and decreased plasma fibrinogen by 18%. No alterations in other hemostatic variables, including plasma activity of Factors VII, VIII, IX, and X and antithrombin, or in the concentrations of von Willebrand Factor, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, glucose, Apo A-1, or lipoprotein(a) were observed in either group.

Other risk factors for cardiovascular disease, including hematocrit, white blood cell count, plasma viscosity, systolic and diastolic blood pressures, heart rate, and platelet aggregation after stimulation with ADP or collagen did not change. Our results indicate that seal oil supplementation in healthy, normocholesterolemic subjects decreased the n-6/n-3 ratio and increased EPA, DHA, and DPA and the ratio of EPA/AA and DHA/AA in the serum phospholipid and NEFA, while exhibiting a modest beneficial effect on fibrinogen and protein C levels.

Effects of dietary marine oils and olive oil on fatty acid composition, platelet membrane fluidity, platelet responses, and serum lipids in healthy humans.

The influence of various dietary marine oils and olive oil on fatty acid composition of serum and platelets and effects on platelets and serum lipids were investigated as part of an extensive study of the effects of these oils on parameters associated with cardiovascular/thrombotic diseases. Healthy volunteers (266) consumed 15 mL/d of cod liver oil (CLO); whale blubber oil (refined or unrefined); mixtures of seal blubber oil and CLO; or olive oil/CLO for 12 wk. In the CLO, seal oil/CLO, and whale oil groups, serum levels of eicosapentaenoic acid (EPA) were increased. In platelets, EPA was increased in the CLO, seal/CLO, and olive oil/CLO groups. The localization of n-3 polyunsaturated fatty acids in the triacylglycerols did not seem to influence their absorption.

Intake of oleic acid is poorly reflected in serum and platelets. No significant differences in triacylglycerols (TG), total cholesterol, or high density lipoprotein cholesterol were observed, even though TG were reduced in the CLO, CLO/seal oil, and whale oil groups. Mean platelet volume increased significantly in both whale oil groups and the CLO/olive oil group. Platelet count was significantly reduced in the refined whale oil group only. Lipopolysaccharide-stimulated blood tended to generate less thromboxane B2 in CLO, CLO/seal, and CLO/olive groups. The whale oils tended to reduce in vivo release of beta-thromboglobulin. In conclusion, intake of various marine oils causes changes in platelet membranes that are favorably antithrombotic. The combination of CLO and olive oil may produce better effects than these oils given separately. The changes in platelet function are directly associated with alterations of fatty acid composition in platelet membranes.

Modulation of atherosclerotic risk factors by seal oil: a preliminary assessment.

We examined whether dietary supplementation with seal oil influenced the risk factors of atherosclerosis in healthy volunteers. Two intervention studies were carried out as preliminary steps in a larger project which aim at elucidating the disease preventive potential of seal oil. In study I ten healthy volunteers added 10 capsules of seal oil to their normal Western diet for six weeks. Blood tests were analysed for total-, HDL-, and LDL-cholesterol and plasma triglyceride, and the ratio of n-6/n-3 fatty acid was determined in plasma and erythrocyte membranes. In study II we examined the effect in five healthy volunteers who had only 5 capsules of seal oil daily for six weeks. As an additional test in study II, the effect on the proinflammatory TNF-alpha cytokine in lymphocytes was determined. A slightly decreased, however, not significant effect was observed for each of the cholesterol's after seal oil supplementation. In both studies plasma triglyceride, and the n-6/n-3 fatty acid ratio of plasma and erythrocytes were significantly reduced upon seal oil intake. During the intervention period of study II a distinct reduced level of TNF-alpha was observed in isolated lymphocytes. The examinations suggest that supplementation of seal oil, 10 capsules or 5 capsules/day, may have beneficial effects on factors thought to be associated with cardiovascular and thrombotic diseases.

Effects of duodenal seal oil administration in patients with inflammatory bowel disease.

Long-chain n-3 PUFA in fish oil have modulating effects on inflammatory responses. The aim of this open pilot study was to investigate whether duodenal seal oil administration would benefit patients with inflammatory bowel disease (IBD). Seal oil (10 mL) was administered three times a day directly into the distal part of the duodenum via a nasoduodenal feeding tube for 10 d in 10 patients, 5 of whom had Crohn's disease and 5 ulcerative colitis. Nine of the 10 patients suffered from IBD-associated joint pain. Various parameters of disease activity and FA incorporation in tissues were analyzed before and after treatment. Following seal oil therapy, joint pain index, disease activity, and serum cholesterol level were significantly decreased, whereas the n-3 to n-6 ratio both in intestinal biopsies and blood was significantly increased. Measures of calprotectin concentration in gut lavage fluid, intestinal permeability, and lipid peroxidation were not significantly changed. The results suggest positive effects of seal oil in patients with IBD, especially on IBD-associated joint pain. Further controlled studies are warranted.

Research projects on seal oil and seal meat - results so far

Results from a research collaboration between National Institute of Nutrition and Seafood Research (NIFES) and Haukeland University Hospital (HUH) indicate that seal oil ameliorate musculoskeletal (joint) pain in patients with chronic inflammatory diseases like inflammatory bowel disease (IBD). The results so far are promising, but larger controlled studies are necessary in order to confirm these results.


The research collaboration on seal oil between NIFES and HUS started in 1998. Seal oil is extracted from the seals' blubber and contains a high proportion of the long chained polyunsaturated omega-3 fatty acids, similar to different kinds of fish oil (approx. 20 %). Both refined and unrefined oils from different seal species have been used. All oils used complied with legislation with respect to content of undesirable substances. Patients at the Institute of Gastroenterology, HUH, suffering from gastrointestinal diseases were the main target group in the research.

The seal oil studies

A pilot study, published in 2002(Arslan et al. 2002), examined the effect of giving seal oil to 10 patients suffering from inflammatory diseases (IBD, chronic inflammatory disease, ulcerative colitis, and Crohns disease) and joint pain. When given seal oil (10 ml, 3 times a day) for 10 days via a (nasoduodenal) tube into the small intestine, the patients reported an amelioration of their joint pains. However, the intestinal symptoms were only slightly improved. The treatment was repeated for five of the patients at a later stage, and they were examined by a rheumatologist before and after the treatment, confirming that the joint pain was reduced.

The results of Arslan's pilot study were confirmed through a controlled study published in 2004 (Bjorkkjer et al. 2004). Here, 19 IBD patients with joint pain got the same treatment with seal oil or soy oil for 10 days through a nasoduodenal tube, and were followed up for 6 months after the treatment by a rheumatologist. During the study period the patients receiving seal oil claimed improvement of their joint pain compared to the patients given soy oil. The effect of the seal oil lasted up to several months after the treatment.

Analysis of seal meat

A study of nutrients in seal blubber and seal meat was recently carried out and published in Food Chemistry (Brunborg et al. 2005). Seal blubber contains high proportions of long chained unsaturated omega- 3 fatty acids and mono unsaturated fatty acids. Seal meat is lean (< 2 % fat) and is protein rich with a well balanced amino acid composition. In addition, it contains a high concentration of minerals, especially iron. Seal meat has high levels of vitamin A, D3 and B12. More studies are at various stages of publication (revised version, submitted to be evaluated, or in progress) and will be summarised here when they are published.

More information: Arslan G., Brunborg L.A., Froyland L., Brun J.G., Valen M., and Berstad A. (2002). Effects of duodenal seal oil administration in patients with inflammatory bowel disease. Lipids 37, 935-940. Bjorkkjer T., Brunborg L.A., Arslan G., Lind R.A., Brun J.G., Valen M., Klemetsen B., Berstad A., and Froyland L. (2004). Reduced joint pain after short-term duodenal administration of seal oil in patients with inflammatory bowel disease: Comparison with soy oil. Scand. J. Gastroenterol. 11, 1088-1094. Brunborg L.A., Julshamn K., Nordtvedt R., and Froyland L. (2005). Nutritional composition of blubber and meat of hooded seal (Cystophora cristata) and harp seal (Phagophilus groenlandicus) from Greenland. Food Chemistry (Article in press).

Effects of long-term feeding of marine oils with different positional distribution of eicosapentaenoic and docosahexaenoic acids on lipid metabolism, eicosanoid production, and platelet aggregation in hypercholesterolemic rats.

Ikeda I

Yoshida H

Tomooka M

Yosef A

Imaizumi K

Tsuji H

Seto A

Laboratory of Nutrition Chemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were distributed mainly in the sn-1,3 positions of seal oil triglyceride and in the sn-2 position of squid oil triglyceride. Seal oil-rich or squid oil-rich fats having constant saturated/monounsaturated/polyunsaturated fatty acid (PUFA) and n-6/n-3 PUFA ratios were fed to exogenously hypercholesterolemic rats for 1 60 d. The control fat contained linoleic acid as the sole PUFA. Before starting the experimental diets, rats were orally treated with high doses of vitamin D for 4 d to accelerate atherogenesis. The percentage of arachidonic acid in phosphatidylcholine and phosphatidylethanolamine of liver, platelets, and aorta was lower in the marine oil groups than in the control group, seal oil being more effective than squid oil. Maximal platelet aggregation induced by collagen was significantly lower in both marine oil groups. Platelet thromboxane (TX) A2 production induced by collagen or thrombin was markedly reduced by feeding seal or squid oils, the reduction being more pronounced in the seal oil than in the squid oil group. Aortic prostacyclin (PGI2) production was the same among the three groups. The ratio of the productions of aortic PGI2 and platelet TXA2 was significantly higher in the seal oil than in the control group. Although there was no difference in intimal thickness among the three groups, the aortic cholesterol content was significantly lower in the marine oil groups than in the control group. These results showed that the main effects in rats of the different intramolecular distributions of EPA and DHA in dietary fats were on arachidonic acid content in tissue phospholipids and on platelet TXA2 production.

Effect of marine oils supplementation on coagulation and cellular activation in whole blood.

Osterud B

Elvevoll E

Barstaf H

Brox J

Halvorsen H

Lia K

Olsen JO

Olsen RL

Sissener C

Rekdal O, et al

Department of Biochemistry, University of Tromso, Norway

A study was performed to explore the effects of supplemental intake of various marine oils known to be part of the Eskimo diet. Healthy men and women (134) were randomly selected to consume 15 mL/d of oil from blubber of seal, cod liver, seal/cod liver, blubber of Minke whale, or no oil for ten weeks. Total cholesterol was unchanged in the oil groups, whereas high density lipoprotein cholesterol increased 7% in the seal/cod liver oil (CLO) group (P < 0.05) and 11% in the whale oil group (P < 0.005). Triacylglycerol was significantly reduced in the CLO group only. The concentration of prothrombin fragment 1 + 2 was reduced 25% (P < 0.05) after whale oil supplementation. No change in fibrinogen or factor VIIc was detected. Tumor necrosis factor generation in lipopolysaccharide (LPS)-stimulated blood was 30% reduced after whale oil (P < 0.05), but was unaffected by intake of seal or CLO. The LPS-induced tissue factor activity in monocytes was reduced to a significant degree only in the seal/CLO group (34%) and whale oil group (35%) (P < 0.05). The most dramatic change in thromboxane B2 in LPS-stimulated blood was seen after whale oil intake with 44% reduction (P < 0.01). Supplementation of a regular diet with a combination of seal oil and CLO and especially with whale oil seems to have beneficial effects on several products thought to be associated with cardiovascular and thrombotic diseases.

Human study: N-3 PUFA from fish- or seal oil reduce atherogenic risk indicators in Danish women

Bente Deutch MPH, PhDCorresponding Author Contact Information, Eva Bonefeld Jorgensen Ph D and Jens C Hansen Dr Med

Department of Environmental and Occupational Medicine, Aarhus University, DK-8000, Arhus, Denmark

In a previous pilot study among healthy young Danes intake of 5 and 10 gram seal oil per day significantly reduced serum triglycerides but did not significantly influence total cholesterol, HDL-or LDL-cholesterol. The aim of the present study was to test and compare this effect of seal oil with intake of fish oil capsules in a controlled study. The study was designed as a randomised, double blind, placebo controlled clinical trial, in which 78 young normolipidemic women were given 5 capsules a day of either fish oil, fish oil with B12, seal oil, or placebo consisting of “average” Danish fat, during a 3–4 months intervention period, followed by 8 weeks of washout period, no capsules. The participants answered questionnaires about dietary habits, other lifestyle factors and anthropometric parameters. The compliance was followed by blood and gluteal fat lipid profiles. During the three months intervention there were gradual reductions in total serum cholesterol and triglycerides in all treatment groups. In paired sample t-tests, the effects of fish oil with B12 were highly significant p<0.01 whereas fish oil alone, P=0.07, and seal oil, P=0.09, were borderline significant. Multiple regression analysis showed that the reductions in TG and atherogenic risk index were strongly correlated to concomitant increases of n-3/n-6 ratio in gluteal fat, an association which highly depended on the consumed n-3 dose and was independent of the type of marine oil used.

Marine Fatty Acids in Relation to Inflammatory Bowel Diseases (IBD) Bjelland, LA

University of Bergen, Institute of Fisheries and Marine Biology Bergen Norway. 108 pp. Nov 2000.

The omega-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (20:5 omega -3, EPA) and docosahexaenoic acid (22:6 omega -3, DHA) have modulating effects on inflammatory mechanisms in the intestine and on the immune response in general. EPA and DHA are incorporated into membrane phospholipids where they are replacing arachidonic acid (20:4 omega -6, AA). C20 fatty acids are the precursors of eicosanoids. When EPA is the precursor it inhibits competitively the formation of AA precursor eicosanoids, namely leukotrien (LT) B sub(4) and prostaglandin (PG) E sub(2), which are more potent in inflammation reactions than the products of EPA, namely LTB sub(5) and PGE sub(3). In the present study ten patients suffering from inflammatory bowel disease (IBD) were given 30 grams of seal oil (i.e. 4.4 grams of EPA + DHA) daily for a period of ten days. The oil was injected through a nasojejunal feeding tube directly to the jejunum to secure that a greater deal of omega -3 PUFA reached the inflamed area of the intestine. The fatty acid composition of oils from marine mammals is somewhat different than oils from fish, regarding the positional distribution of the omega -3 PUFA (i.e, EPA and DHA). Analysis included fatty acid composition of serum, buffy coat, red blood cells and biopsies from rectal mucosa, gut lavage fluid calprotectin concentration, intestinal permeability, serum cholesterol (CH) and triacylglycerol (TAG) concentrations, and an indirect measurement of lipid peroxidation (TBARS concentration). In addition, scores of joint pain and disease activity were determined. The results showed that after seal oil supplementation, omega -3 fatty acids were incorporated at the expense of omega -6 fatty acids in all blood samples and rectal biopsies. Calprotectin concentration decreased slightly, whereas the intestinal permeability increased slightly. Serum CH and TAG concentrations were lowered. There was no sign of increased lipid peroxidation. Both joint pain index and disease activity were markedly lower after treatment with seal oil.


Barbara Meyer 1, Amanda Lane 1, Neil mann 2

1 School of Health Sciences and Smart Foods Centre, University of Wollongong,    NSW 2522

2 SCHOOL APPLIED SCEINCES (Food Science), RMIT University, Melbourne, 3000

Background - Numerous health benefits have been attributed to both eicosapentaenoic acid (EPA, 20:5n3) and docosahexaenoic acid (DHA, 22:6n3) found in fish oil. However, docosapentaenoic acid (DPA, 22:5n3) found particularly in red meat has been less well studied. Australians consume 6 times more meat than we do fish. The richest commercial capsule source of DPA available is seal oil. Objective - To compare the effects of DPA rich seal oil supplementation with DHA rich fish oil, on measures of plasma lipids in hypertriglyceridaemic subjects. Design - A randomised, parallel, placebo controlled, double blind study was conducted in 52 hypertriglyceridaemic subjects. They were randomly allocated to one of three groups receiving a total of 1g/d EPA, DPA & DHA but different relative amounts: seal oil capsules (360mg EPA, 250mg DPA, 450mg DHA), fish oil capsules (210mg EPA, 30mg DPA, 810mg DHA) or placebo capsules (containing a vegetable oil) for 6 weeks. Fasting blood samples were taken at baseline and at 6 week post intervention. Blood samples were tested for red blood cell (RBC) fatty acids and plasma lipids (triglycerides, total cholesterol, LDL-cholesterol and HDL-cholesterol). Results - The placebo group did not change at all in any of the parameters measured. Seal oil supplementation significantly increased incorporation of DPA (from 2.5-2.7%), DHA (from 4.9-5.8%) and EPA (from 1-1.8%), p<0.0005), whereas fish oil increased incorporation of DHA only (from 5.2-6.2%), p<0.01 into RBC. Baseline plasma triglyceride levels were not significantly different between the 3 groups. Plasma triglycerides remained unchanged in the placebo group (2.30-2.36mmol/l), whilst reductions of 7% (2.24-2.09mmol/l) and 14% (2.54-2.19mmol/l) were seen in the fish oil and seal oil groups respectively, but only the seal oil group reached significance (p<0.05). No differences were seen in any groups in HDL-cholesterol levels. Conclusion – Seal oil supplementation increased RBC levels of DPA, EPA and DHA whilst DHA rich fish oil supplementation increased RBC levels of DHA only. It appears that seal oil is more effective than fish oil at lowering plasma triglyceride levels in hypertriglyceridaemic subjects.

Acknowledgement - Supported by funding from Meat and Livestock Australia