Effect of cereal fibre source and processing on rectal epithelial cell proliferation

Area of Science:

• Gastroenterology
• Nutritional Science
• Oncology

Background:

• Previous research indicated low-fat diets and wheat bran reduced adenoma growth and rectal cell proliferation.
• High-fat diets are associated with increased risk of colorectal adenomas.

Purpose of the Study:

• To investigate the impact of unprocessed wheat bran, unprocessed oat bran, and processed wheat bran (All Bran) on rectal epithelial cell proliferation.
• To assess the effects of these fiber interventions in individuals with a history of adenomas on a high-fat diet.

Main Methods:

• A randomized cross-over trial involving 20 subjects with recent adenomas and high-fat diets.
• Subjects consumed oat bran (64 g/day), wheat bran (25 g/day), or All Bran (38 g/day) for six-week periods, alongside a low-fat diet (<25% energy).
• Rectal biopsy specimens were analyzed for cell proliferation using the proliferating cell nuclear antigen (PCNA) marker.

Main Results:

• No significant differences in mean labeling indexes (a measure of cell proliferation) were observed across the control, wheat bran, oat bran, and All Bran diets.
• Wheat bran consumption showed the lowest activity of labeled cells in the top two-fifths of crypts, though not statistically significant.
• Analysis of whole cell distribution and total fiber intake did not reveal significant effects on proliferation.

Conclusions:

• In this cohort of high-risk individuals, dietary fiber from various bran sources, combined with a low-fat diet, did not significantly affect rectal epithelial cell proliferation.
• Wheat bran exhibited a trend towards reducing cell proliferation in the upper crypts, warranting further investigation.