If you’ve dieted at any point in your life, most likely you were told or understood to avoid potatoes, bananas or plantains, and rice because of their high-starch content. And, as dieters know, starch turns into sugar, which is stored as fat inside the body, or so it was thought.
New research has emerged, putting these “forbidden foods” back in favor and has food manufacturers looking for ways to reproduce what their starchy compounds do inside the body.
Benefits of Resistant Starch
Scientists have discovered that these often-avoided foods contain “resistant starch,” which is proving, they say, to have previously undetected health benefits, including decreased blood sugar and even weight loss in some cases.
Studies show that resistant starch, or RS, doesn’t get digested and absorbed in the small intestine like its cousin carbohydrate, the standard form of starch. Instead, resistant starch – also found in beans or legumes and whole grains – passes through the small intestine into the large intestine, or colon, where it is broken down by bacteria living there.
That process, known as fermentation, also happens when fiber is consumed. That’s why some nutrition experts group resistant starches with fiber, even calling them a type of fiber. Like fiber, they regulate appetite by making us feel fuller faster and longer, and feed the natural bacteria we need in our digestive tract. Yet, unlike fiber, that has some undesirable effects such as bloating, increased flatulence and abdominal discomfort, researchers say [1] resistant starches are well tolerated at higher levels.
“The reason this research is getting a lot of attention is because these resistant starches are found in foods we typically enjoy but have avoided, since carbohydrates have been shown to increase insulin needs and fat storage,” said Alice Pereira, a registered dietitian with Baptist Health. “With the obesity and diabetes epidemics, carbohydrates have been demonized.”
Ms. Pereira says these “skinny carbs,” as some are calling these foods with resistant starch, don’t spike your blood sugar to the same degree as other types of carbohydrates. So, your body doesn’t need to produce as much insulin to rid your blood of that extra sugar. Furthermore, since your body expends more energy to break these starches down, the overall amount of calories consumed is less with resistant starches than with digestible starches. So, you get the fullness of fiber and the satisfaction of eating carbohydrates without the increased insulin needs and fewer calories. Plus, the beneficial bacteria living in your colon get the nutrients they need to survive and thrive.
Other Sources of Resistant Starch
While the latest research focuses on starchy fruits and vegetables, whole grains and whole seeds also contain resistant starch and are therefore beneficial to your health.
Other research claims that by simply allowing cooked rice or potatoes to cool before eating them helps increase resistant starch in these foods.
Food manufacturers are also finding ways of adding resistant starch to ingredients used in making foods like bread and pasta. High-amylose corn starch [2], for example, is currently being used in place of flour to increase resistant starch levels and decrease calories in some foods. And researchers are looking for ways to add resistant starch to wheat, according to the U.S. Department of Agriculture [3].
Moderation Is Still Key
Yet, despite the research and development of scientifically modified foods, Ms. Pereira still recommends moderation and naturally occurring resistant starches versus the manufactured ones.
“We don’t yet know the long-term effects that over-consuming these starches will have,” she warns. “And, while there’s a documented calorie reduction in foods with resistant starch, it really only amounts to one to two calories per gram of starch less, so overeating can still cause weight gain.”
For diabetics and pre-diabetics, Ms. Pereira urges them not to experiment with resistant starches without speaking to their doctor or nutritionist about how they should continue monitoring their blood sugar levels.
Also, Ms. Pereira and others [4] caution that a large variation exists in the way that resistant starches are measured, so claims on foods of resistant starch amounts should be considered estimates.
“Even though there are claims that some foods are high in resistant starch,” Ms. Pereira said, “Those foods still may be bad for you, nutritionally speaking, so use caution.”