Fatty acid composition of dietary fat
plays a vital role in colon tumor development in animal models. Fats containing
ω-6 fatty acids (e.g., corn oil) enhanced, and ω-3 fatty acids (e.g.,
flaxseed oil) reduced chemically-induced colon tumor development in rats. Lignans have also been shown to prevent colon tumor
development in experimental animals. The objective of the present investigation
is to study the effects of dietary flaxseed meal, a source of both ω-3
fatty acid and lignans on colon tumor development,
and compare with the effects of dietary corn meal. Male Fischer rats, two
groups of 24 each were assigned to the AIN-93M diet supplemented with either
15% corn meal or 15% flaxseed meal, respectively. Carcinogensis
was initiated with subcutaneous injections of azoxymethane
(15mg/kg) once a week for three consecutive weeks. After 35 weeks of
initiation, rats were anesthetized with ether. Blood was collected by cardiac
puncture and rats were sacrificed. The gastrointestinal tract was isolated. The
site, size and number of tumors were recorded. The fatty acid analysis of the
collected serum and colon samples was performed. Expression of COX-1 and COX-2
was performed by Western blot method. Lignan levels
in serum and colon samples were assayed.