Variability in anticancer lignan levels in flaxseed

Thompson, Lilian U.; Rickard, Sharon E.; Cheung, F; Kenaschuk, E. O.; Obermeyer, William R.

doi:10.1080/01635589709514497

Cited by 86 publications

(54 citation statements)

References 22 publications

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“…In addition, there are various analytical methods for determining food values ; hence, databases compiled from published values determined by different methodologies may contain inherent errors. It has also been shown that the amount of lignans in food can differ according to crop variety, location, year of harvest and processing (Thompson et al, 1997;Kuijsten et al, 2005). Dietary measurement error associated with FFQs (food frequency questionnaires) is also possible.…”

Section: Discussionmentioning

confidence: 99%

Lignans and breast cancer risk in pre- and post-menopausal women: meta-analyses of observational studies

et al. 2009

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Phyto-oestrogens are plant compounds structurally similar to oestradiol, which have been proposed to have protective effects against breast cancer. The main class of phyto-oestrogens in the Western diet is lignans. Literature reports on the effect of lignans in breast cancer risk have been conflicting. We performed three separate meta-analyses to examine the relationships between (i) plant lignan intake, (ii) enterolignan exposure and (iii) blood enterolactone levels and breast cancer risk. Medline, BIOSIS and EMBASE databases were searched for publications up to 30 September 2008, and 23 studies were included in the random effects meta-analyses. Overall, there was little association between high plant lignan intake and breast cancer risk (11 studies, combined odds ratio (OR): 0.93, 95% confidence interval (95% CI): 0.83 -1.03, P ¼ 0.15), but this association was subjected to marked heterogeneity (I 2 ¼ 44%). Restricting the analysis to post-menopausal women, high levels of plant lignan intake were associated with reduced breast cancer risk (7 studies, combined OR: 0.85, 95% CI: 0.78, 0.93, Po0.001) and heterogeneity was markedly reduced (I 2 ¼ 0%). High enterolignan exposure was also associated with breast cancer (5 studies, combined OR: 0.73, 95% CI: 0.57, 0.92, P ¼ 0.009) but, again, there was marked heterogeneity (I 2 ¼ 63%). No association was found with blood enterolactone levels (combined OR: 0.82, 95% CI: 0.59 -1.14, P ¼ 0.24). In conclusion, plant lignans may be associated with a small reduction in post-menopausal breast cancer risk, but further studies are required to confirm these results. (Beral, 2003) have both been associated with increased breast cancer risk. Isoflavones and lignans are plant compounds structurally similar to 17b-oestrodiol known as phyto-oestrogens, capable of oestrogen receptor binding (Kuiper et al, 1998;Mueller et al, 2004). Isoflavones are mostly found in soybean products, which are a staple of the Asian diet, whereas lignans are the principal group of phyto-oestrogens in Western diets. Lignans are more widespread in foods than isoflavones and are present in grain cereals, vegetables, seeds, tea and coffee (Mazur, 1998a;Mazur et al, 1998b). Microflora in the colon (Setchell et al, 1981) convert plant lignans into enterolignans, which are detectable in blood and urine. Their levels have been correlated with the amount of plant lignans ingested (Nesbitt et al, 1999).In a recent meta-analysis, an inverse dose-response relationship was shown between breast cancer risk and soy-food intake in Asian, but not in Western women (Wu et al, 2008). Lignans have been shown to exhibit anti-carcinogenic properties (Wang et al, 1994;Prasad 2000;Bergman Jungeström et al, 2007), and it is hypothesised that exposure to high levels may be associated with a reduction in breast cancer risk. However, results from a number of studies in Western populations have been variable. The aim of our systematic review was to establish whether an association exists between lignan exposure and breast cancer ris...

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Section: Discussionmentioning

confidence: 99%

Lignans and breast cancer risk in pre- and post-menopausal women: meta-analyses of observational studies

et al. 2009

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“…Good sources of lignans in the United States and Europe are pumpkin seed (20 mg/100 g), sunflower seed, cranberry, black tea, coffee, garlic, broccoli, brans, and peanuts (62). Green tea is a rich source of lignans and a popular beverage in many Asian countries (63).…”

Section: Dietary Sourcesmentioning

confidence: 99%

Cross-species and interassay comparisons of phytoestrogen action.

Whitten

Patisaul

2001

Environ Health Perspect

174

105

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This paper compiles animal and human data on the biologic effects and exposure levels of phytoestrogens in order to identify areas of research in which direct species comparisons can be made. In vitro and in vivo assays of phytoestrogen action and potency are reviewed and compared to actions, dose-response relationships, and estimates of exposure in human subjects. Binding studies show that the isoflavonoid phytoestrogens are high-affinity ligands for estrogen receptors (ERs), especially ER beta, but have lower potency in whole-cell assays, perhaps because of interactions with binding proteins. Many other enzymatic actions require concentrations higher than those normally seen in plasma. In vivo data show that phytoestrogens have a wide range of biologic effects at doses and plasma concentrations seen with normal human diets. Significant in vivoresponses have been observed in animal and human tests for bone, breast, ovary, pituitary, vasculature, prostate, and serum lipids. The doses reported to be biologically active in humans (0.4--10 mg/kg body weight/day) are lower than the doses generally reported to be active in rodents (10--100 mg/kg body weight/day), although some studies have reported rodent responses at lower doses. However, available estimates of bioavailability and peak plasma levels in rodents and humans are more similar. Steroidogenesis and the hypothalamic-pituitary-gonadal axis appear to be important loci of phytoestrogen actions, but these inferences must be tentative because good dose-response data are not available for many end points. The similarity of reported proliferative and antiproliferative doses illustrates the need for fuller examination of dose-response relationships and multiple end points in assessing phytoestrogen actions.

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“…The major nutritional components of flaxseed include oil, viscous lignanrich fibres (mucilage), protein and minerals, which are analyzed by American Oil Chemists Society (AOCS). Flaxseed is the richest source of a -linolenic acid (18:3n-3), soluble and insoluble fibre, and mammalian lignan precursor secoisolariciresinol diglucoside (SDG) (1,2). Flaxseed has long history of use in India.…”

Section: Introductionmentioning

confidence: 99%