Lipids. 1987 Oct;22(10):711-4.
Enteral absorption in man of eicosapentaenoic acid in different chemical forms.
el Boustani S, Colette C, Monnier L, Descomps B, Crastes de Paulet A, Mendy F.
Laboratoire de Biochimie A, Institut de Biologie, Montpellier, France.
After administering the equivalent of 1 g of eicosapentaenoic acid (EPA) in four different chemical forms, the kinetics of EPA incorporation into plasma triglycerides (TG) were compared by gas liquid chromatography on a capillary column following separation of the lipid fraction by thin layer chromatography. EPA incorporation into plasma TG was markedly smaller and later when EPA was administered as an ethyl ester rather than as EPA free fatty acid, EPA arginine salt or 1,3-dioctanoyl-2-eicosapentaenoyl glycerol (2-EPA). Our results and the data in the literature are compatible with the hypothesis that 2-EPA is absorbed with minimum hydrolysis and escapes random distribution between the other positions of the glycerol molecule during the absorption process
Biochem Biophys Res Commun. 1988 Apr 15;152(1):328-35.
Human absorption of fish oil fatty acids as triacylglycerols, free acids, or ethyl esters.
Lawson LD, Hughes BG.
Murdock Pharmaceuticals, Springville, Utah 84663.
The transient rise in plasma triacylglycerol fatty acids after single-dose ingestion of fish oil as triacylglycerols, free acids, or ethyl esters with linseed oil as an absorption standard was used to determine the relative absorption of fish oil fatty acids in eight men. As free acids, the fish oil fatty acids were well absorbed (greater than or equal to 95%). As triacylglycerols, eicosapentaenoic acid (1.00 g) and docosahexaenoic acid (0.67 g) were absorbed only 68% and 57% as well as the free acids. The ethyl esters were absorbed only 20% and 21% as well as the free acids. The incomplete absorption of eicosapentaenoic and docosahexaenoic acids from fish oil triacylglycerols correlates well with known in vitro pancreatic lipase activity.
Lipids. 1992 Nov;27(11):858-62.
The absorption of fish oils and concentrates.
Ackman RG.
Canadian Institute of Fisheries Technology, Technical University of Nova Scotia, Halifax, Canada.
Both preventive and curative therapies have created a considerable demand for eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The most common sources for omega 3 fatty acids are fish oil. The concentrations of EPA and DHA in commercial oils, after modest enrichment, reach about 300 mg/g; alternative technologies can produce reasonably priced fish oils containing 400 or even 500 mg/g of omega 3 acids. When the acids are liberated from the glycerides, concentrates of ethyl esters or free acids with 65 to 70% total omega 3 fatty acids (at least 50% EPA + DHA) are readily prepared. Difficulties have arisen because most clinical trials have used fish oils of unspecified composition, and some trials are now based on either ethyl esters or free acids. There are at least three different, but not mutually exclusive, absorption routes in humans, namely the preduodenal route, the lymphatic route via chylomicrons, and the route via the portal vein to the liver. This makes it difficult to compare results. The difficulty in obtaining dose-related clinical data may in part be due to the form in which the omega 3 acids are offered and due in part to the natural presence of these fatty acids in the body. The nontriglyceride forms, especially the free acids, have been advocated for standardization of trials to facilitate interlaboratory comparisons.
Life Sci. 1993;52(16):1371-9.
Lymphatic transport of eicosapentaenoic and docosahexaenoic acids as triglyceride, ethyl ester and free acid, and their effect on cholesterol transport in rats.
Ikeda I, Imasato Y, Nagao H, Sasaki E, Sugano M, Imaizumi K, Yazawa K.
Laboratory of Nutrition Chemistry, Kyushu University School of Agriculture, Fukuoka, Japan.
Lymphatic transport of docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids given in the forms of triglyceride, ethyl ester of free acid and their effect on cholesterol transport was compared in lymph-cannulated rats. Lymphatic recovery of DHA and EPA given by stomach tube in the form of triglyceride in which they were mainly located at the 2-position was significantly higher than that of the ethyl ester or free acid during the first 6 hr after the administration and the tendency continued until 9 hr. In contrast, the 9 to 24 hr recovery of DHA and EPA in the forms of ethyl ester and free acid was considerably higher than that of triglyceride. Consequently, cumulative 24 hr recovery of EPA was comparable among the three forms. However, the 24 hr recovery of DHA was highest in free acid, lowest in ethyl ester and intermediate in triglyceride. Recovery of the free acid between 9 and 24 hr after administration was significantly higher than that given in the forms of triglyceride or ethyl ester. Cholesterol recovery in lymph of rats given with ethyl ester or free acid was lower than that given with triglyceride at an early stage after the. administration in both EPA and DHA. Cumulative 24 hr recovery of cholesterol in rats given these fatty acids as ethyl ester was significantly lower than in those given as the other two forms.
Arzneimittelforschung. 1990 Jun;40(6):700-4.
[Comparative bioavailability of eicosapentaenoic acid and docasahexaenoic acid from triglycerides, free fatty acids and ethyl esters in volunteers]
[Article in German]
Beckermann B, Beneke M, Seitz I.
Bereich Forschung und Entwicklung der Troponwerke GmbH & Co. KG, Koln.
Comparative Bioavailability of Eicosapentaenoic Acid and Docosahexaenoic Acid from Triglycerides, Free Fatty Acids and Ethyl Esters in Volunteers. The bioavailability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from triglycerides, free fatty acids and ethyl esters was investigated in 8 female volunteers in a randomized triple cross-over trial with baseline control. EPA/DHA was administered in capsules in form of triglycerides (1.68/0.72 g), free fatty acids (1.35/1.065 g) and ethyl esters (1.86/1.27 g). The resulting EPA/DHA plasma levels were determined and evaluated. The mean relative bioavailability of EPA/DHA compared to triglycerides was 186/136% from free fatty acids and 40/48% from ethyl esters. Maximal plasma levels were about 50% higher with free fatty acids and about 50% lower with ethyl esters as compared to triglycerides.