Bowel cancer is the second most common cancer in Australia. Research shows that eating fibre rich in resistant starch is one way we can combat this threat. This animation shows how resistant starch moves through the intestine, feeds the healthy bacteria of the gut microbiome and helps prevent cancer.
NARRATOR: We know that many plant foods benefit our health. Scientists now believe one reason for this lies with the gut microbiome—the bacteria in your intestines.
Your microbiome is nourished by meals like this, rich in one type of dietary fibre called resistant starch. Resistant starch can't be digested by your body, but instead becomes food for your gut bacteria.
Most starch is easily digested. Starch is dissolved in the small intestine and then absorbed by your body, providing you with energy and nutrients. The remaining, non-digestible portion is called resistant starch. The resistant starch continues its journey through your gut and arrives at the large intestine.
We see that the resistant starch has become exposed to the healthy bacteria of the gut microbiome. This species of bacteria specialise in breaking down the resistant starch. This breakdown process provides the bacteria with the fuel they need to survive. As they use the starch for energy, they release small carbohydrate molecules. The neighbouring bacteria feed on these carbohydrates.
As he bacteria feed, they excrete even smaller molecules as waste. One of the final waste products is called butyrate, an energy source for your body.
As the butyrate builds up, it is absorbed by the large intestine. The presence of butyrate encourages blood to flow into the vessels of the large intestine, keeping the tissue healthy. If your diet includes enough resistant starch, these cells will use butyrate as their main source of energy.
Here, we can see the molecular surface of one of the intestinal cells. The surface is covered in special proteins that actively pump butyrate molecules into the cell. Once inside, they can be harvested for energy. In addition, butyrate has other benefits.
Intestinal cells are sensitive to DNA damage, caused by environmental factors. This cell's DNA has been damaged, resulting in a mutation. More damage could accumulate over time as the cell divides, which could lead to colorectal cancer. But, a steady supply of butyrate allows the DNA damage to be more easily detected, and, the cell can activate a suicide program in response. Because the damaged cell destroys itself, it can't progress to form a cancer.
A starved microbiome is unable to protect you from cancer. By eating foods rich in resistant starch, you can nourish your microbiome and improve your health!