Dose Effects of Flaxseed and Its Lignan on N-Methyl-N-Nitrosourea-Induced Mammary Tumorigenesis in Rats

January 1, 1999 Human Health and Nutrition Data 0 Comments

Dose Effects of Flaxseed and Its Lignan on N-Methyl-N-Nitrosourea-Induced Mammary Tumorigenesis in Rats

Year: 1999
Authors: Rickard, S.E., Yuan, Y.V., Chen, J., Thompson, L.U.
Publication Name: Nutr. Cancer
Publication Details: Volume 35; Number 1; Pages 50-57.


Dietary supplementation with flaxseed or its lignan secoisolariciresinol diglycoside (SDG) has reduced dimethylbenz[a]anrhracene-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 afler injection with MNU (50 mg/kg body wt ip), 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 multipliciy 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 a-linolenic acid present in the BD. Author's Abstract.

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