Starches of varied digestibilities differentially modify intestinal function in rats

Area of Science:

• Gastroenterology
• Nutritional Science
• Colonic Physiology

Background:

• Dietary starches vary in digestibility, influencing their fermentation and impact on the colon.
• Understanding how resistant starches affect colonic function is crucial for dietary interventions.

Purpose of the Study:

• To investigate the effects of different starch digestibilities on colonic function in a rat model.
• To compare the impact of raw potato starch, high amylose cornstarch, arrowroot starch, and cooked potato starch on the large intestine.

Main Methods:

• Male Fischer 344 rats were fed diets containing 25% of specific starches for 6 weeks.
• Measurements included fecal weight, transit time, colonic cell proliferation (thymidine kinase activity), and cecal/colonic parameters (weight, starch content, pH).

Main Results:

• Raw potato starch showed significantly lower digestion, leading to a 32-fold increase in undigested starch reaching the cecum.
• Both high amylose cornstarch and raw potato starch increased fecal weight and induced large intestinal hypertrophy, with raw potato starch showing the greatest effect.
• Raw potato starch significantly increased transit time (50% longer), luminal acidity, and bulk, while high amylose cornstarch only increased fecal bulk.

Conclusions:

• High amounts of undigested starch entering the colon, particularly raw potato starch, promote luminal bulk, acidity, and slower transit.
• Resistant starches can induce significant changes in colonic physiology, including hypertrophy and altered transit, with effects varying based on digestibility.