Effects of Dietary Wheat Bran Fiber on Rectal Epithelial Cell Proliferation in Patients With Research for Colorectal Cancers
Document Type
Article
Publication Date
8-1-1990
Description
A preponderance of carcinogenesis studies in rodents and epidemiologic studies in humans suggests a potential role of dietary fiber in the prevention of colorectal cancer. Recently, wheat bran fiber used as a dietary supplement has been shown to decrease the growth of rectal adenomatous polyps in patients with familial poluposis; however, few studies of high-risk human populatins have been attempted to determine the effects of dietary fiber supplementation on markersn of carcinogenesis in the colon or rectum. We have designed a one-arm study to evaluate the effects of dietary supplementation with wheat bran fiber [i.e., 13.5 g/day for 8 wk; after 1 mo, 2 g/day (compliance evaluation period)] on [3H]thy-midine rectal mucosa cell labeling (i.e., percent of epithelial cells incorporating [3H]thymidine into DNA in intact rectal crypt cells over a 90-min exposure as well as in minced rectal biopsy tissue over a 24-hr exposure) in rectal biopsy speciamens. The biopsy specimens were obtained at sigmoidoscopy in 17 compliant patients with a history of resected colon or rectal cancer. We categorized patients as having initaially low or initially high [3H]thymidine-labeling indices (i.e., percent of mucosa cells that incorporate [3H]thymidine into DNA during 1.5-or 24-hour in vitro incubations) by using the median baseline labeling index as a cutoff between high and low values. On the basis of a chi-square test used to identify patients with a statistically significant (P<. 001) change, six of the eight patients who initially had high 24-hour outgrowth labeling indices showed a significant decrease in the rectal mucosa biopsy specimens obtained after treatment. An over-all 22% decrease was observed in rectal mucosa cell biopsy specimens obtained at study termination (P<.001). Of the eight patients with initially high total [3H]thymidine-labeling indices in crypt organ culture, four had a significant (P <.001) decrease from baseline values, one had a significant increase, and three showed no change following the fiber intervention. The wheat bran fiber dietary supplement of 13.5 g/day was well tolerated by this group of older (54-70 yr) patients. Although the [3H]-thymidine labeling index data suggest that the wheat bran fiber supplement can inhibit DNA synthesis and rectal mucosa cell proliferation in high-risk patients, the resulta of this small pilot study should not be overinterpreted vis á vis the potential role of wheat bran fiber as a chemopreventive agent for colorectal cancer. Study results should be confirmed in the setting of a randomized double-blined clinical trial in colorectal cancer patients. Intermediated markers of carcinogenesis should be used as end points. [J Natl Cancer Inst 82: 1280-1285, 1990]
Citation Information
Alberts, D. S.; Einspahr, J.; Rees-mcgee, S.; Ramanujam, P.; Buller, M. K.; Clark, L.; Ritenbaugh, C.; Atwood, J.; Pethigal, P.; Earnest, D.; Villar, H.; Phelps, J.; Lipkin, M.; Wargovich, M.; and Meyskens, F. L.. 1990. Effects of Dietary Wheat Bran Fiber on Rectal Epithelial Cell Proliferation in Patients With Research for Colorectal Cancers. Journal of the National Cancer Institute. Vol.82(15). 1280-1285. https://doi.org/10.1093/jnci/82.15.1280 PMID: 2165179 ISSN: 0027-8874