Lignan Content of the Flaxseed Influences Its Biological Effects in Healthy Men and Women

January 1, 2013 Human Health and Nutrition Data 0 Comments

Lignan Content of the Flaxseed Influences Its Biological Effects in Healthy Men and Women

Year: 2013
Authors: Almario, R.U. Karakas, S.E.
Publication Name: J Amer. College Nutr.
Publication Details: Volume 32; Number 3; Pages 194-199


The n3 polyunsaturated fatty acid (n3 PUFA) as well as lignan components of flaxseed (FLX) can have beneficial effects. In this 6-week-long, randomized, double-blinded, placebo-controlled study, we investigated the effects of FLX lignans on cardiovascular risk factors. Thirty-seven subjects (13 men and 24 women, age: 54  plus or minus  7 years, body mass index [BMI]: 29.7  plus or minus  1 kg/m2) consumed nutrition bars with similar macronutrient contents. The fatty acid composition and the lignin contents of the bars differed significantly. Two FLX bars both contained 3.0 g of alpha linolenic acid (ALA: 18:3 n3) but different amount of lignans (0.15 g vs. 0.41 g). High lignan FLX decreased total cholesterol (C) by 12 percent  (p equal  0.044), LDLC by 15percent  (p  equal  0.022), and oxidized (Ox) LDL by 25percent  (p equal  0.035). Regular FLX tended to increase OxLDL by 13 percent  (p equal  0.051).  The difference between the effects of high-lignan vs. regular lignan FLX on OxLDL was highly significant (p equal  0.004).  High lignan FLX has the unique property of decreasing OxLDL, which is an independent risk factor for cardiovascular disease. (Authors abstract)
A limited number of studies in humans that compared flaxseed (FLX) oil to FLX lignan indicated that lignans are important due to the atheroprotective effects of FLX.  The most atherogenic lipid fraction in the circulation is low density lipoprotein (LDL). The oxidized form of LDL (OxLDL) is considered even more atherogenic than LDL. This study compared the effects of low lignan (1percent  by weight) vs high lignan (5 percent  by weight) FLX specifically on the oxidation of LDL . In addition, changes in plasma lipids as well as 2 inflammatory markers: C reactive protein (hsCRP) and fatty acid binding protein 4 (FABP4).  Regular lignan FLX and high lignan FLX had similar amounts of ALA but differed in their lignan contents.  Soybean and regular lignan FLX had similar amounts of total PUFA but the composition of the PUFA was different; SBO contained primarily essential n6 PUFA LA whereas regular lignin FLX contained primarily ALA.
Regular lignan FLX increased plasma triglycerides significantly, whereas high lignan FLX and SBO did not affect triglyceride levels. The high lignan FLX lowered LDLC more than the regular lignan FLX did. And high lignan FLX reduced LDL oxidation.  In the present study, no decrease in hs CRP with either regular lignan FLX or high lignan FLX was noted. Serum FABP4, which is an emerging risk factor for atherosclerosis was assessed.  No change in FABP4 levels in any of the treatment arms were observed.  In conclusion, the lignan content of the FLX influenced its biological effects in humans. Thus, specific attention should be paid to the lignan content of supplements when designing and/or interpreting the results of clinical studies. (Editors comments)

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