Resistant starch is beginning to be understood as an important component of a healthy diet, and cassava flour is a good source.
Ordinary starch in food is digested, converted to a sugar called glucose, and absorbed into our blood for use by cells throughout the body. We like to eat starchy foods like bread and pasta, but if we ingest too much, our blood sugar levels can spike and cause sudden production of insulin to deal with all that blood sugar.
Insulin, a hormone produced by the pancreas, prompts our cells to absorb glucose from the blood, providing fuel for the cells to do their thing. But when the amount of sugar in the blood rises quickly to a high level, the body responds by producing a large amount of insulin, resulting in rapid assimilation of sugar, particularly into muscles, fat, and liver tissue. Repeated overproduction of insulin can hinder many bodily processes: it can delay healing, increase the risk of infection, promote inflammation, damage nerves, cause heart disease, degrade blood vessels (increasing risk of heart attack and stroke), increase the chance of colorectal cancer, and (of course) cause the insensitivity to insulin that is the hallmark of Type 2 diabetes.
The term “resistant starch” refers to starch that is not digested and absorbed as it travels through our digestive tract, akin to dietary fiber. Resistant starch thus reaches the large intestine intact, where it can be fermented—eaten, you might say—by the legion of friendly bacteria that populate our gut. So the benefits of resistant starch start with its not being converted into blood sugar and causing the potential problems we discussed above; but the game-changing magic of resistant starch is in this nourishment and encouragement of our precious gut microbiome. These bacteria in the lower intestine play a significant role not only in digestion, but in many aspects of our health and psychology.
We have evolved in partnership with these microflora in our belly, so it is no real surprise that they make multiple contributions to our wellbeing. The gut contains half a billion nerve cells, connected to the brain by the vagus nerve, which transmits signals in both directions, so conditions in the digestive system can affect mood and mental health. Gut microbes produce a number of important chemicals called neurotransmitters, which affect feelings and emotions. A well-known example is serotonin, which can boost happy feeling and control the body clock; over 90% of our serotonin is produced by bacteria in the colon. Healthy, well-fed gut flora produce a number of crucially important short-chain fatty acids, such as butyrate, which contributes to the health of the cells lining the large intestine and can help reduce the risk of colon cancer. The gut microbiome produces B-complex vitamins, affects inflammation throughout the body, plays an important role in the regulation of our immune system.
So one way to promote our own health is to support the lifestyle of the bacteria that reside in the large intestine, by eating food that gives them something to chew on. Resistant starch provides this prebiotic function, nourishing the gut microbiome. One delicious source of resistant starch is cassava flour.