The phrase "resistance is futile" entered the pop-culture lexicon in 1989 when The Borg appeared on an episode of Star Trek: The Next Generation. The show's creators probably had no idea that somewhere in a laboratory in England, scientists were making bold, new discoveries about how simple foods battle the diseases threatening the health of modern mankind. During the 1980s, English researchers discovered an amazing component of complex carbohydrates which they named "resistant starch" for its resilience during its voyage through the human digestive system.
Unlike The Borg which forcefully assimilated other races with injected microscopic nanoprobes, resistant starch enters our system when we willingly eat beans, sweet potatoes or other tubers, and whole grains. It survives the assault of digestive enzymes in the stomach and small intestine, only deploying its life-promoting weapons when seized by bacteria in the colon. Although it is possible for humans to resist the beneficial effects of resistant starch by avoiding foods rich in fiber and complex carbohydrates, the question is, "Why would we want to?"
Benefits of Resistant Starch
When we eat foods containing resistant starch, our first benefit is an increased experience of satiety; it helps us feel full and satisfied with foods that are low in calories but high in nutrition. Next, we find that because it is not metabolized until later in the digestion process, foods with resistant starch help to keep our insulin levels stable because foods with resistant starch won't cause a spike in our blood sugar. Research is also exploring the promising role that resistant starch appears to play in preventing and treating obesity and metabolic syndrome, two diseases threatening those eating a Western diet of animal products and processed food.
Rosane Oliveira, DVM, PhD, in her article, Who Can Resist a Resistant Starch?, cites four additional benefits of resistant starch:
• maintaining the health of the lining of the colon
• lower intestinal inflammation
• balanced gut microbes, and
• lower risk of chronic illnesses like type 2 diabetes, heart disease, and some cancers.
Butyrate Makes Us Better
Carbohydrates are a macronutrient which is made up of three components: simple sugars, starches (also known as "complex carbohydrates"), and fiber. Fiber can be further divided into two categories. Soluble fiber is so named because it is soluble in gastrointestinal fluid, giving the liquid a viscous consistency similar to honey. Insoluble fiber is not soluble in gastrointestinal fluid nor can it be broken down by gut bacteria. It serves to add bulk to digestive wastes. Depending on who's doing the defining, resistant starch may either be considered a complex carbohydrate which functions similarly to dietary fiber, or it may be listed as a third type of fiber which has low-viscosity and largely resists metabolism until it reaches the colon. No matter how it is defined, research indicates that resistant starch seems to benefit us the most when it is eaten as part of a whole food, bundled together with the other forms of fiber present in whole plant foods, rather than in a purchased powder form to be mixed with water.
According to Dr. Oliveira, once resistant starch reaches the colon, gut-friendly microbiota begin the process of fermentation, "producing short chain fatty acids, which lower the pH level of your colon contents encouraging the growth of healthy bacteria in the gut." Butyrate is one of these short chain fatty acids and is believed to be responsible for much of the benefits of resistant starches such as lower colon cancer risk, reduced intestinal inflammation, and obesity reversal. The following video traces the digestive path of complex carbohydrates from eating to fermentation in the colon, graphically demonstrating how butyrate nourishes the colon and helps it resist disease.
What Makes Starch Resistant?
Guy Crosby, PhD, who teaches nutrition at Harvard School of Public Health, explains why this type of starch resists enzymatic digestion. First, he says, "It is important to realize that resistant starch is not a distinct molecular structure like glucose or cholesterol, but a concept developed to explain why some starch is not digested." Then, he points out that while some of the resistance is due to the starch being physically inaccessible to digestive enzymes, most of the resistance comes from the chemical structure of the starch. Starch is formed by two molecules, amylose and amylopectin. These molecules — particularly amylose — "form crystalline regions that are resistant to digestion by the starch digesting enzymes in our body."
Four Types of Resistant Starch
Just as there is more than one type of fiber, resistant starch also comes in varying types. These can be classified by their structure and by how resistant they are to digestion.
RS1 - are starches which are physically protected from digestion by intact cell walls. Milling of grains or chewing begins the process of breaking the cell walls to make these starches available. Legumes, seeds, and whole grains are examples of RS1.
RS2 - represents starch that is protected from enzyme digestion by its granular form. Raw potatoes and green bananas are good examples.
RS3 - is retrograde starch which is formed when a starchy food is cooked and then cooled, allowing the starch crystals to reform after heating. Cooked and cooled potatoes, rice, or pasta contain RS3.
RS4 - is manufactured as a food additives. It is the result of a chemical process and is not found in nature.
The Beans, Not The Borg
In 2013, The Borg was named #4 on TV Guide's list of the "60 Nastiest Villains of All Time." But rather than mounting a defense against resistant starch, it's time we lower our shields and surrender to the amazing effects of this truly marvelous component of whole plant foods. Beans are the Number One food we can eat to obtain resistant starch. Once fully cooked, says Dr. Crosby, about four to five percent of the total weight of beans is resistant starch. While that may not sound like much, it is four to five times higher than other starchy foods like baked potatoes or white bread.
Resistant starch is one of the reasons beans are such a good choice for a Starch-Smart® breakfast and lunch. Beans have the power to fill us up and keep us fueled through the most demanding hours of the day. Other whole foods like sweet potatoes, yams, green plantains, and whole grains are also resistant starch stars. No matter which ones you choose to assimilate, you can be sure that you will benefit from all the disease fighting power of resistant starch.
(1) Jeff Novick - Are Cold Starches Really Less Fattening?