Flaxseed has been shown in previous studies to decrease some early markers of
colon cancer risk in part because of its
lignans. This study determined whether the intake of flaxseed and
lignans is related to the activity of bacterial
beta-glucuronidase, an
enzyme suggested to increase
colon cancer risk. Seven groups of six female rats each were fed, for four weeks, a basal high-fat (20%) diet (BD), BD supplemented with 2.5%, 5.0%, or 10.0% flaxseed, or BD with daily gavage of 0.75, 1.5, or 3.0 mg of
secoisolariciresinol diglycoside (SDG), the major mammalian
lignan precursor. The specific and total activities of
beta-glucuronidase in the cecum were significantly related to the levels of flaxseed (r = 0.539, p < 0.008 and r = 0.599, p < 0.002, respectively) and SDG (r = 0.567, p < 0.007 and r = 0.435, p < 0.04, respectively). The urinary mammalian
lignan excretion also increased with increasing flaxseed or SDG levels and thus was significantly related to the specific activity (r = 0.38, p < 0.017) and total activity (r = 0.429, p < 0.007) of
beta-glucuronidase. Because flaxseed and
lignans are
colon cancer protective, it is concluded that, in contrast to other studies,
beta-glucuronidase activity may play a beneficial role in their presence by increasing mammalian
lignan absorption and enterohepatic circulation.