Damon Stewart, DC, CSCS, NSCA-CPT & Kristina Virro, BA (Hon), MA, RHN
For years, health advocates have touted the many benefits of fiber, typically referring to soluble and insoluble fiber for the most part. Recently, however, research has revealed that there is another type of fiber that we should be incorporating into our diets whenever possible: resistant starch.
What is Resistant Starch?
Well, its name is somewhat self-explanatory: resistant starch is a type of starch that resists digestion. In other words, it is not fully broken down and absorbed in the small intestine. Instead, these starches remain in-tact by the time they reach the large intestine, at which point they will act as prebiotic fibers that ferment and provide food for microbes. This process causes them to be converted into short chain fatty acids (SCFAs), which offer a number of benefits to the body, which we will discuss later in this post.
What are the Different Types of Resistant Starch?
There are actually four different types of resistant starch, which are differentiated by their structure or source:
• RS1: digestive enzymes cannot access this type of resistant starch, therefore they avoid breakdown in the small intestine. Sources include whole grains, seeds, and legumes.
• RS2: resists digestion because of the nature of the granule. Sources include raw potatoes, unripe bananas, and some legumes.
• RS3: produced when certain foods are cooked and then cooled. Sources include bread, tortillas, potatoes, rice, and pasta.
• RS4: a chemically-modified starch found in a variety of products.
RS3 is a particularly fascinating type of resistant starch. You see, when raw starches are heated, their chemical structure is loosened. As such, the sugars are broken down and released into our bloodstream very easily. However, when these starches are cooled again, their structure is reorganized and actually contains more resistant starch. This is a good thing considering the many benefits that come from resistant starch and the short-chain fatty acids they produce. This also means that we can actually alter the amount of resistant starch found in foods like rice, pasta, potatoes, and other starches by simply cooling and reheating them.
In one small study, participants were asked to consume freshly-cooked pasta, cooked-then-cooled pasta, or cooled-and-reheated pasta. Turns out, the more times a food was cooled and reheated, the more resistant starch there was. In fact, those who ate the pasta that had been cooked, cooled, and then reheated experienced a reduced rise in blood glucose by a whopping 50%! This stat has huge implications when it comes to diabetes, fat loss, and overall body composition manipulation.
What are the Benefits of Resistant Starch?
1. Improved Gut Health: We have talked in previous posts about the benefits of having a healthy gut, but the importance of your gut microbiota to your overall health cannot be overstated. Your gut not only digests the foods you consume, extracts the nutrients, and separates waste, but it also ensures that your immune system and metabolism are well-regulated, sustains the gastrointestinal tract, boosts cognitive health and function, and even supports your mental well-being. Resistant starch feeds this incredibly important bacteria in your gut, leading to better health in all of these areas.
2. Improving Inflammatory Bowel Disease: Butyrate, one type of short-chain fatty acid, has anti-inflammatory properties that can help improve diseases like ulcerative colitis and Crohn’s disease, which are characterized by chronic inflammation of the bowel. Additionally, short-chain fatty acids also may help prevent and treat colon cancer.
3. Improved Blood Sugar Control: According to the journal Bioscience, Biotechnology, and Biochemistry, acetate—another short-chain fatty acid—has an inhibitory effect on a specific transcription factor that regulates genes required for the conversion of glucose to fatty acids in the liver. In other words, short-chain fatty acids increase enzyme activity in the muscles and liver, which results in improved blood sugar control. What’s fascinating is that research has shown that the ingestion of resistant starch not only improved insulin sensitivity during the meal in which you consume the resistant starch; you will also experience increased insulin sensitivity during subsequent meals!
4. Weight Loss: The “thermic effect of food” is a term that refers to the increase in your metabolism after you eat something. Naturally, certain foods require more energy to digest than others. For example, 20 – 35% of the calories found in protein are burned through the very processing of this macronutrient versus the 0 – 5% of calories that are burned when fats are processed. Because resistant starches resist digestion, they require a lot more energy to burn, thereby assisting your weight loss efforts.
5. Improved Satiety: Like soluble and insoluble fiber, resistant starch leads to increased feelings of fullness, which will not only help you feel more full and satisfied after a meal, but will also help you with any weight loss goals.
How to Incorporate More Resistant Starch into Your Diet
1. Eat More Unripe Bananas: The greener a banana, the more resistant starch it contains. As it ripens, however, the structure of the starch changes and you will lose the benefits associated with resistant starch. So, why not cut up a slightly green banana over some probiotic-filled yogurt or kefir for a gut-friendly snack? Another easy strategy is to freeze your unripe bananas and throw them in the blender with your morning shakes. One time to possibly avoid this strategy is immediately following your workout where an insulin spike is beneficial due to the anabolic effects of this hormone.
2. Eat More Leftovers: When starches are cooled and then reheated, their resistant starch increases, so reheat those leftovers you normally don’t eat. They actually contain more gut-friendly short-chain fatty acids than your original meal!
3. Cook and Cool Starches Whenever Possible: On your next pasta night, for example, make a big batch of pasta, let it cool, then pour some boiling water over top to reheat it before dinner. This will increase the amount of resistant starch and improve insulin sensitivity during your meal, which is always a good thing!
4. Eat More Foods High in Resistant Starch: Foods like legumes, oats, and whole grains are easy to add into your diet and contain a significant amount of resistant starch.
5. Try Unmodified Potato Starch: Bob’s Red Mill Unmodified Potato Starch contains 8 grams of resistant starch per tablespoon with practically no carbohydrates. Try adding it to your morning smoothie, building up slowly to avoid experiencing too much uncomfortable gas at first.
Resistant starch is a wonderful nutrient that helps improve gut health, encourages weight loss, decreases inflammation, and improves blood sugar regulation. Resistant starch is not only easy to incorporate into our diet, but we can tweak the amount in some of our favorite foods like potatoes and pasta!