Dietary lignans: physiology and potential for cardiovascular disease risk reduction

Abstract

The present review of the literature on lignan physiology and lignan intervention and epidemiological studies was conducted to determine if lignans decrease the risks of cardiovascular disease in Western populations. Five intervention studies using flaxseed lignan supplements indicated beneficial associations with C-reactive protein, and a meta-analysis that included these studies also suggested lignans have a lowering effect on plasma total and low-density lipoprotein cholesterol. Three intervention studies using sesamin supplements indicated possible lipid- and blood pressure-lowering associations. Eleven human observational epidemiological studies examined dietary intakes of lignans in relation to cardiovascular disease risk. Five showed decreased risk with either increasing dietary intakes of lignans or increased levels of serum enterolactone (an enterolignan used as a biomarker of lignan intake), five studies were of borderline significance, and one was null. The associations between lignans and decreased risk of cardiovascular disease are promising, but they are yet not well established, perhaps due to low lignan intakes in habitual Western diets. At the higher doses used in intervention studies, associations were more evident.

Conflict of interest statement

Conflict of Interest: None

© 2010 International Life Sciences Institute.

Figures

Figure 1. Structures of monolignols, lignans, and lignins

Figure 2. Sketch of flaxseed seocisolariciresinol lignan oligomer

The flavonoid herbacetin can be interchanged with secoisolariciresinol diglucoside. The number of units (n) are usually 1-7 with an average of 3. The terminal unit can have 3-hydroxy-3-methy-glutaric acid, ferulic acid glucoside or p-coumaric acid glucoside. Both cinnamic acid glycosides (ferulic acid glucoside or p-coumaric acid glucoside) are shown here to demonstrate where each one is esterified to secoisolariciresinol diglucoside. Based on work by Strandas et al (2008), Struijs et al (2007), Struijs et al (2008), Struijs et al (2009).

Figure 3. Structure and sources of individual lignans common in foods

Figure 4. Bioconversion of plant lignans to enterolignans in the human gut

Simplified from and based on work by Clavel et al (2006), Kuijsten et al (2005), and Lampe et al (2006) for secoisolariciresinol diglucoside and Jan et al (2009) and Liu et al (2006) for sesaminol triglucoside.