flax

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These are the only three abstracts on medline under a search for flax AND

carcinogen. All are positive for flax.

 

Nutr Cancer 2000;37(2):187-92

 

Exposure to flaxseed or purified lignan during lactation influences rat

mammary gland structures.

Ward WE, Jiang FO, Thompson LU.

Department of Nutritional Sciences, University of Toronto, Toronto, ON,

Canada M5S 3E2.

Previous investigation demonstrated that feeding a 10% flaxseed (10F) diet

during pregnancy and lactation enhanced the differentiation of highly

proliferative terminal end bud (TEB) structures of rat mammary gland into

less proliferative alveolar buds and lobules. From this study, it was

hypothesized that the lignan component in flaxseed mediated the observed

effects. Because mammary glands with more TEBs are more susceptible to

carcinogens, exposure to flaxseed during early postnatal life may reduce

the risk of developing mammary cancer. Our objectives were to elucidate

whether exposure to flaxseed during lactation only and during pregnancy

and lactation can similarly influence the differentiation of mammary gland

structures and also to identify whether the lignan component of flaxseed

is the biologically active agent. Offspring were exposed to a 10F diet or

a dose of purified lignan equivalent to that in a 10F diet (10S) during

lactation only or from lactation to postnatal Day 50. Compared with

controls, exposure to 10F or 10S during lactation only or from lactation

to postnatal Day 50 reduced the number of TEBs and resulted in a rise in

the number of alveolar buds. In conclusion, exposure to flaxseed or its

purified lignan during lactation is a critical period in which mammary

gland development may be promoted by enhancing the differentiation of the

mammary gland structures. However, continuous exposure, particularly to

purified lignans, resulted in the most differentiation of the mammary

gland. The next step is to determine whether the changes in mammary gland

structures are chemopreventive in rats challenged with a carcinogen.

PMID: 11142092 [PubMed - indexed for MEDLINE]

 

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2: Cancer Lett 2000 Dec 8;161(1):47-55

 

Plasma insulin-like growth factor I levels in rats are reduced by dietary

supplementation of flaxseed or its lignan secoisolariciresinol diglycoside.

Rickard SE, Yuan YV, Thompson LU.

Department of Nutritional Sciences, Faculty of Medicine, University of

Toronto, 150 College Street, Ontario M5S 3E2, Toronto, Canada.

Flaxseed and its lignan secoisolariciresinol diglycoside (SDG) inhibit

mammary tumor development in rats. Increased plasma insulin-like growth

factor I (IGF-I) concentrations are associated with increased breast

cancer risk. Therefore, the effect of flaxseed (5%) or SDG (1.5 mg/day)

supplementation on plasma IGF-I levels was examined in rats treated with

or without N-methyl-N-nitrosourea (MNU). In MNU-free rats, flaxseed and

SDG reduced plasma IGF-I levels, which were inversely related to urinary

lignan excretion. Only flaxseed significantly reduced plasma IGF-I

concentrations in MNU-treated rats. The anticancer effect of flaxseed and

SDG may be related, in part, to reductions in plasma IGF-I.

PMID: 11078912 [PubMed - indexed for MEDLINE]

 

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3: Nutr Cancer 1999;35(1):50-7

 

Dose effects of flaxseed and its lignan on N-methyl-N-nitrosourea-induced

mammary tumorigenesis in rats.

Rickard SE, Yuan YV, Chen J, Thompson LU.

Department of Nutritional Sciences, Faculty of Medicine, University of

Toronto, ON, Canada.

Dietary supplementation with flaxseed or its lignan secoisolariciresinol

diglycoside (SDG) has reduced dimethylbenz[a]anthracene-induced mammary

tumor size and number in rats. The objective of this study was to

determine whether flaxseed has a dose-dependent effect on

N-methyl-N-nitrosourea (MNU)-induced mammary tumor promotion and whether

this effect can be attributed to its SDG. Two days after injection with

MNU (50 mg/kg body wt i.p.), female Sprague-Dawley rats were fed a

high-fat (20% soybean oil) AIN-93G basal diet alone (BD) or supplemented

with flaxseed (2.5% F and 5% F) or SDG by gavage [sDG in 2.5% F (LSDG) and

SDG in 5% F (HSDG)] for 22 weeks. Although tumors tended to be smallest in

the 5% F group throughout the experimental period, flaxseed feeding did

not significantly affect tumor size, multiplicity, or incidence in

comparison to BD. However, there was a dose-dependent effect of SDG on

tumor multiplicity. Tumor multiplicity was lowest in the HSDG group and

highest in the LSDG group throughout treatment (p < 0.05), indicating that

HSDG inhibited, whereas LSDG promoted, MNU-induced mammary tumor

development. Tumor invasiveness and grade were decreased in all treatment

groups compared with the BD (p < 0.032). Thus, although flaxseed feeding

had no significant effect on tumor growth indexes, flaxseed and SDG

treatment, regardless of dose, appeared to delay the progression of

MNU-induced mammary tumorigenesis. Disparities between this study and

previous studies on flaxseed may be related to differences in experimental

design, the use and dose of a different carcinogen, and protective effects

by the alpha-linolenic acid present in the BD.

 

 

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