Results from a study funded National Health and Medical Research Council of Australia published in Cancer Prevention Research, a journal of the American Association for Cancer Research, demonstrates that the consumption of a type of starch that acts like fiber may help reduce colorectal cancer risk associated with a high red meat (HRM) diet.
“Red meat and resistant starch have opposite effects on the colorectal cancer-promoting miRNAs, the miR-17-92 cluster,” explained Karen J. Humphreys, PhD, a research associate at the Flinders Center for Innovation in Cancer at Flinders University in Adelaide, Australia. “This finding supports consumption of resistant starch as a means of reducing the risk associated with a high red meat diet.”
“Total meat consumption in the U.S., the European Union, and the developed world has continued to increase from the 1960s, and in some cases has nearly doubled,” Humphreys added.
…consumption of resistant starch [may] reducing the risk associated with a high red meat diet…
Escaping digestion
“Unlike most starches, resistant starch escapes digestion in the stomach and small intestine, and passes through to the colon (large bowel) where it has similar properties to fiber,” Humphreys explained. “Resistant starch is readily fermented by gut microbes to produce beneficial molecules called short-chain fatty acids, such as butyrate.”
“Good examples of natural sources of resistant starch include bananas that are still slightly green, cooked and cooled potatoes [such as potato salad], whole grains, beans, chickpeas, and lentils. Scientists have also been working to modify grains such as maize so they contain higher levels of resistant starch,” Humphreys noted.
Bringing levels down
After eating 300 grams of lean red meat per day for four weeks, study participants had a 30% increase in the levels of certain genetic molecules called miR-17-92 in their rectal tissue, and an associated increase in cell proliferation. Consuming 40 grams of butyrated resistant starch per day along with red meat for four weeks brought miR-17-92 levels down to baseline levels.
The study involved 23 healthy volunteers, 17 male and six female, ages 50 to 75. Participants either ate the red meat diet or the red meat plus butyrated resistant starch diet for four weeks. After a four-week washout period the participants switched to the other diet for another four weeks.
For more information:
Humphreys KJ, Conlon MA, Young GP, Topping DL, Hu Y, Winter JM, Bird AR, et al. Dietary Manipulation of Oncogenic MicroRNA Expression in Human Rectal Mucosa: A Randomized Trial. Cancer Prev Res (Phila). 2014 Aug;7(8):786-95. doi: 10.1158/1940-6207.CAPR-14-0053.[Article][PubMed]
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