A mineral-rich red algae extract inhibits polyp formation and inflammation in the gastrointestinal tract of mice on a high-fat diet

Abstract

The purpose of this study was to determine whether a mineral-rich extract derived from the red marine algae Lithothamnion calcareum could be used as a dietary supplement for chemoprevention against colon polyp formation. A total of 60 C57bl/6 mice were divided into 3 groups based on diet. One group received a low-fat, rodent chow diet (AIN76A). The second group received a high-fat "Western-style" diet (HFWD). The third group was fed the same HFWD with the mineral-rich extract included as a dietary supplement. Mice were maintained on the respective diets for 15 months. Autopsies were performed at the time of death or at the completion of the study. To summarize, the cumulative mortality rate was higher in mice on the HFWD during the 15-month period (55%) than in mice from the low-fat diet or the extract-supplemented high-fat diet groups (20% and 30%, respectively; P < .05 with respect to both). Autopsies revealed colon polyps in 20% of the animals on the HFWD and none in animals of the other 2 groups (P < .05). In addition to the grossly visible polyps, areas of hyperplasia in the colonic mucosa and inflammatory foci throughout the gastrointestinal tract were observed histologically in animals on the high-fat diet. Both were significantly reduced in animals on the low-fat diet and animals on the extract-supplemented HFWD.These data suggest that the mineral-rich algae extract may provide a novel approach to chemoprevention in the colon.

Fig. 1

Appearance of normal colonic mucosa and tumors (colonic polyps) in the caecum of mice on the HFWD. A and D: Gross appearance (under the dissecting microscope) and histological appearance of the mucosal surface of normal colonic mucosa. The normal colonic mucosal folds are apparent at the gross level. B, C, E and F: Gross and histological appearance of polyps identified when the caecum was opened longitudinally and examined under the dissecting microscope. (D, E and F: Hematoxylin and eosin. Bar = 200 μm).

Fig. 2

A: Histological appearance of an abnormal crypt in the colon of a mouse on the HFWD. The crypt is elongated and has cells with a variety of shapes and sizes. Many of the cells have a serrated border and lack the ordered differentiation seen in normal colonic mucosa. Inflammatory cells are prevalent. B: Histological appearance of an area of the colon containing an inflammatory cell nodule. While the nodule itself is in the submucosa, inflammatory cells extend to the base of the mucosal epithelium. (A: Hematoxylin and eosin. Bar = 50 μm; B: Hematoxylin and eosin. Bar = 100 μm).