The effects of dietary fiber from Lagenaria scineraria (yugao-melon) on colonic carcinogenesis in mice.
BACKGROUND
The increasing trend of colon cancer in Japan is attributed to changes in dietary habits, that is, increased amounts of fat and decreased amounts of fiber in the diet. The effects of Japanese dietary fiber from Lagenaria scineraria (yugao-melon) on colonic carcinogenesis in mice were examined.


METHODS
Eighteen ICR mice in each group were fed with either a basal diet or a diet containing 5%, 10%, or 20% of yugao powder for 35 weeks. All the mice received a weekly intraperitoneal injection of 1,2-dimethylhydrazine (DMH), 10 mg/kg body weight for 10 weeks. The effects of yugao powder on the mucosal and luminal variables involved in colonic carcinogenesis were then compared with those of wheat bran in the mice without any carcinogen treatment.


RESULTS
The incidence of colon tumors (adenocarcinomas) was lower in the yugao powder diet groups than in the basal diet group at week 35 (24% vs. 50%, P < 0.05). The bile acid concentration in the colon was reduced in all the fiber diet groups except for the 5% yugao powder diet group. The colonic luminal pH acidified as yugao powder contents also increased in the yugao powder diet groups. The findings on the colonic short chain fatty acids, microflora, and mucosal fatty acids and ornithine decarboxylase activity were all inconsistent with a tendency to either develop or to inhibit carcinogenesis in both the fiber diet groups.


CONCLUSIONS
Dietary fiber from yugao-melon suppressed DMH-induced colonic carcinogenesis in mice by lowering the bile acid concentration and pH in the colon. The results of the luminal and mucosal variables examined also suggested that the mechanisms of action of yugao powder against colonic carcinogenesis differed from those of wheat brain.
Furukawa
K
K
Department of Internal Medicine 4, Hyogo College of Medicine, Japan.
Yamamoto
I
I
Tanida
N
N
Tsujiai
T
T
Nishikawa
M
M
Narisawa
T
T
Shimoyama
T
T
D000230:Adenocarcinoma / Q000209:etiology*; D000818:Animals; D001647:Bile Acids and Salts / Q000032:analysis; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000209:etiology*; D004043:Dietary Fiber; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D005638:Fruit; D005753:Gastric Mucosa / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000382:microbiology; D051379:Mice; D008813:Mice, Inbred ICR; D009955:Ornithine Decarboxylase / Q000032:analysis
D001647:Bile Acids and Salts; D004043:Dietary Fiber; D005227:Fatty Acids; D009955:Ornithine Decarboxylase