The economic benefits for seal products are growing in Canada and the characteristics and benefits of seal oil are essential to the development of the Sealing Industry. Seal oil is different from other marine oils because of its omega-3 fatty acids composition including docosapentaenoic acid (DPA). The latter would have the potential to relieve joint pain.
Inflammatory joint diseases, referred to as “arthritis”, include more than 100 diseases characterized by joint inflammation. arthrite.ca The 2015 Canadian Community Health Survey found that more than 6 million Canadians have arthritis, or one in five adults. Although the risk increases with age, people of all ages can suffer from it. In fact, among individuals with arthritis, 56% are under 65 years of age.
Arthritis falls into two categories: osteoarthritis and inflammatory arthritis (IA). The most common form of IA is rheumatoid arthritis (RA). Enquête sur la santé dans les collectivités canadiennes, 2015
Impact of diet on joint health
Although there are few ways to prevent the onset of IA, some diets, such as the Mediterranean diet, are associated with a lower incidence of RA The Journal of rheumatology 2004;31:1310-9. . In particular, a reduction in inflammation in people with RA has been shown after 12 weeks of such a diet Ann Rheum Dis 2003;62:208-14.. The protective factors linked to the Mediterranean diet are the consumption of olive oil, fish oil as well as fruits and vegetables.
Omega-3 fatty acids
The impact of omega-3 fatty acids in relation to clinical symptoms of IA such as the intensity of joint pain, the number of aching joints, the duration of morning stiffness and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) are well documented. In 2017, a systematic review covering the results of 18 randomized clinical studies involving patients with arthritis pain, reported that taking omega-3 fatty acids of marine origin in doses of 3 to 9.1 g per day for 12 to 52 weeks could reduce joint pain associated with rheumatoid arthritis. Improvement in clinical symptoms and especially arthritis pain was observed in 55% of the studies. These benefits were reflected in a positive correlation between the amount of omega-3 fatty acids consumed and the reduction in joint pain, however unrelated to the duration of supplementation. As for blood markers of inflammation, taking omega-3 fatty acids induced a significant reduction in c-reactive protein (CRP), which is one of the markers of inflammation reflecting the activity of arthritis Madland TM. Calprotectin (S100A8/A9) and S100A12 in inflammatory arthritis. Clinical and epidemiological studies of rheumatoid and psoriatic arthritis. Dissertation for the degree doctor medicinae, University of Bergen 2007.. Thus, all of this work indicates a strong potential for omega-3 fatty acids of marine origin, the consumption of which in a diet or as a supplement could have a positive impact on clinical symptoms linked to IA.
The two main omega-3 fatty acids found in marine oils are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Seal oil differs from other oils of marine origin because it contains a 3rd omega-3 fatty acid in appreciable concentrations, docosapentaenoic acid (DPA) that is not found – or little – in other marine oils. This high level of DPA makes seal oil one of the few natural and substantial sources of DPA. The effects of seal oil on inflammatory diseases have been reported for over ten years, and indicate a trend towards improving the condition of patients with joint pain. Lipids 2002;37:935-40. Scand J Gastroenterol 2004;39:1088-94. Lipids Health Dis 2006;5:6. Prostaglandins Leukot Essent Fatty Acids 2009;81:425-32. In these clinical trials, patients received 10 mL of seal oil three times a day for 10 days, which represented a daily intake of 1.8 – 2.0 g of EPA, 2.2 – 2, 6 g of DHA and 0.9 – 1.0 g of DPA. Half of the studies have shown that such a daily intake significantly reduces joint pain Lipids 2002;37:935-40. Scand J Gastroenterol 2004;39:1088-94., as well as decreases morning stiffness, the number of painful joints and rheumatic activity score as assessed by a doctor, compared to the control group receiving soybean oil Scand J Gastroenterol 2004;39:1088-94.. Improved quality of life has also been observed through reduced body and joint pain Lipids Health Dis 2006;5:6. Prostaglandins Leukot Essent Fatty Acids 2009;81:425-32..
More specifically, the effects of the consumption of seal oil on IA have been evaluated in two randomized controlled clinical trials in patients with polyarticular psoriatic arthritis J Rheumatol 2006;33:307-10. (n = 38) or disease inflammatory bowel disease with joint pain Clin Nutr 2008;27:614-22. (n = 43). When compared to soybean oil, taking 10 mL of seal oil (2.4 g EPA, 2.6 g DHA, 1.1 DPA) three times a day for two weeks improved the overall disease at four weeks post-treatment J Rheumatol 2006;33:307-10.. This improvement was accompanied by a reduction in the number of painful joints, which was not significantly different from the control group. When compared to cod liver oil (2.3 g EPA, 3.7 g DHA, 0.3 g DPA), seal oil tended to decrease pain in several joints, with no significant difference between the two groups (14). These results regarding the benefits of seal oil are promising, but the literature in this area is still too limited. Without a clinical study dedicated to patients with RA, it remains difficult to position the intake of seal oil for possible benefits related to RA.
Furthermore, to our knowledge, the effects of the consumption of seal oil on blood markers of inflammation have not yet been evaluated in humans. Work on animal models has revealed that in rats, harp seal oil (23% omega-3 fatty acids including 6.7% EPA, 10.3% DHA and 4.7% DPA) decreases the production of certain inflammatory markers such as pro-inflammatory cytokines like TNF-α (tumor necrosis factor α) and interleukin (IL) 1β Preventive nutrition and food science 2015;20:83-7.. Even if the latter are not specific to IA, they are important markers of inflammation involved in the mechanisms underlying this pathology, in particular TNF-α which is a therapeutic target of several biological agents treating the disease.
DPA, the omega-3 fatty acid specific to seal oil, has rarely been the subject of research related to IA. In rats, taking DPA monoglycerides (MAG) was compared with taking MAG EPA and DHA (dose equivalent to 3g / day) for seven days Arthritis Res Ther 2015;17:142.. The greatest reductions in the progression and severity of arthritic disease have been seen after taking MAG-DPA and MAG-EPA, and have been associated with reduced serum concentrations of certain pro-inflammatory cytokines (IL-17A, IL-1β, IL-6 and TNF-α). In an animal model of pulmonary hypertension, taking MAG-DPA induced a decrease in NF-κB (nuclear factor-kappa B) Am J Physiol Heart Circ Physiol 2014;307:H574-86.. This protein is involved in the transcription of pro-inflammatory molecules. Activation of NF-κB is characteristic of RA and causes an increase in proinflammatory cytokines Eur J Pharmacol 2016;792:70-7.. These animal studies suggest that the action of DPA on the markers of inflammation associated with IA, which has not yet been validated in humans, but which represent a lead of interest towards a clinical improvement of the related IA symptoms.
In healthy human subjects (n = 143), a negative correlation was observed between the concentrations of DPA in red blood cells and the concentration of C-Reactive Protein CRP Nutrients 2015;7:6390-404.. In patients with inflammatory bowel disease, serum DPA concentrations were inversely correlated with levels of eotaxin-1 (pro-inflammatory cytokine) in tissues from a colon biopsy PLoS One 2016;11:e0156387.. Recently, an observational study evaluated the association between certain inflammatory markers, clinical symptoms of IA and blood levels of omega-3 fatty acids in individuals without a diagnosis of arthritis but who are carriers of anti-CCP3 antigen which is a blood precursor 3-5 years before the appearance of AI Rheumatology (Oxford) 2017;56:2229-36. symptoms. High concentrations of DPA in red blood cells have been shown to significantly correlate with decreased incidence of IA, suggesting that omega-3 fatty acids, and more specifically DPA, may reduce the risk of developing IA in anti-CCP3+ carriers.
All the studies carried out in connection with IA and omega-3 fatty acids of marine origin constitute a solid scientific basis and point to the benefits of these compounds in improving certain symptoms of inflammatory diseases such as IA, and to reduce the appearance of pro-inflammatory and inflammatory markers. However, studies on seal oil are rare, and the data remain insufficient both from the point of view of the samples (size, target population) and on the evaluation of the combination of omega-3 fatty acids ( EPA, DHA, DPA), to make it possible to conclude that this oil has a real benefit. The demonstration in humans of the ability of seal oil to relieve joint pain therefore appears scientifically justified and relevant, which implies setting up a robust clinical trial to study the effects of seal oil rich in DPA on clinical symptoms and certain inflammatory markers in a population suffering from IA, in order to validate the benefits of this unique combination of omega-3 on IA.
The Seals and Sealing Network is proud to announce that thanks to the funding from INNOVAMER program under the Quebec Ministry of Agriculture, Fisheries and Food, the team at the Institute of Nutrition and Functional Foods at Laval University will complete a three-year clinical study on the impact of fatty acids in seal oil on the relief of symptoms associated with rheumatoid arthritis.