Antithromboxane activity of dietary alpha linolenic acid: A pilot study.

January 1, 1996 Human Health and Nutrition Data 0 Comments

Antithromboxane activity of dietary alpha linolenic acid: A pilot study.

Year: 1996
Authors: A Ferretti, V P Flanagan.
Publication Name: Prostaglandins Leukotrienes Essent. Fatty Acids.
Publication Details: Volume 54; Number 6; Page 451.


Numerous studies over the past two decades have conclusively demonstrated the antithrombotic properties of the long-chain n-3 PUFA, in particular ALA found in flaxseed and FO, and EPA and DHA, found in the oils of fatty fish. However, the average Western style diet does not contain flaxseed or flaxseed oil and is low in fish. Thus, many consumers are not able to incorporate the dietary levels of ALA, EPA and DHA necessary to obtain the beneficial effects of n-3 PUFAs. The objective of this study was to determine whether ALA is able to modulate the synthesis of vasoactive eicosanoids derived from AA, TXB2 and PGI2, to a similar extent as EPA and DHA. Previous research has shown that moderate intakes of ALA in the form of FO and CO can reduce thrombotic tendency. However, these results have been questioned because the synthesis of TXB2 and PGI2 was evaluated ex vivo. In this study, synthesis was conducted in vivo through measurements of active metabolites in 24 hour urine samples following a ALA enriched diet. The subject in this study was a normolipidemic male who was fed an experimental diet in which the n-6:n-3 PUFA ratio was reduced from 28:1 during the baseline period to 1:1 for 7 weeks. For the pre- and post-experimental periods, dietary fat consisted of olive (42 g) and corn oil (14 g) in a 3:1 ratio. The experimental diet high in ALA was comprised of canola oil (42 g) and flaxseed oil (14 g). ALA intakes increased from 0.2 % on the baseline diet to 5.1% on the high ALA diet. The levels of n-6 FA were reduced only slightly on the intervention diet. Urinary excretion of 11-dehydrothromboxane B2 and 2,3-dinor-6-oxo-prostaglandin F1 alpha were measured to assess levels of TXB2 and PGI2, respectively. Following the high ALA diet, urinary excretion of 11-dehydrothromboxane declined by 34% compared to baseline levels. The excretion of 2,3-dinor-6-oxo-prostaglandin F1 alpha was similarly affected, indicating that the synthesis of both TXB2 and PGI2 were reduced. Thus, dietary flaxseed oil consumption results in favorable in vivo alterations in eicosanoid synthesis with significant reductions noted in the synthesis of pro-aggregatory eicosanoids. The data supports previous ex vivo assessments indicating that dietary ALA is an effective modulator of thromboxane and prostacyclin biosynthesis. The authors concluded that the eicosanoid-mediated effects of a relatively low intake of ALA are similar to those elicited by EPA and DHA. The data supports the inclusion of ALA rich oils such as flaxseed oil in the diet.

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