Staying away from starchy foods? Not so fast! There’s one kind of starch you want more of in your diet: resistant starch. Resistant starch is unique from the standard starches you find in foods like white bread and pasta. Unlike the starch in a white potato that’s quickly absorbed, resistant starch “resists” digestion and passes straight through your small intestines with minimal absorption.
Once in the colon, friendly, probiotic bacteria feed on resistant starch and produce short-chain fatty acids that help keep the lining of your colon healthy. Some research suggests resistant starch may lower the risk for colon cancer. In addition, resistant starch supports the growth of probiotic bacteria. If you’ve been following the news recently, research shows gut bacteria play an essential role in health, not only digestive health but immune and metabolic health as well.
Why are gut bacteria so important? Research show people who have a healthy population of gut bacteria are less likely to be obese and develop metabolic problems like insulin resistance and type 2 diabetes. That’s important because anything we can do to foster the growth of gut-friendly bacteria has the potential to improve our health. Resistant starch is the nourishment these bacteria need to take up long-term residence in your gut and keep less desirable bacteria out.
To make matters confusing, there are four main types of resistant starch. Let’s take a quick look at each.
Types of Resistant Starch: RS1 Resistant Starch
This type of resistant starch is abundant in whole-grain foods, seeds, and legumes. It has a hard coating that physically protects it from breakdown. Thus, it passes through your body without being absorbed.
Types of Resistant Starch: RS2 Resistant Starch
RS2 resistant starch is a granular starch. Because of its tightly-packed structure, digestive enzymes can’t break it down so it resists digestion and absorption. You find this type of starch in green bananas, high-amylose corn, Basmati rice, and raw potatoes.
Types of Resistant Starch: RS3 Resistant Starch
RS3 starch is also called retrograded starch because it forms when you expose starchy foods, like potatoes, to cold temperatures after cooking them. The classic example is what happens to a cooked potato when you place it in the refrigerator overnight. With cold exposure, a portion of the starch in that starchy potato is converted to resistant starch. You can do the same with parboiled rice. Sounds almost like magic, doesn’t it?
Types of Resistant Starch: RS4 Resistant Starch
RS4 is a synthetic form of resistant starch that’s chemically modified to make it resistant to digestive enzymes. An example is high-maize resistant starch available at some food markets.
The best forms of resistant starch are the first three since you find them in whole, unprocessed foods. How much resistant starch should you consume? While the World Health Organization only gives guidelines for fiber consumption and not resistant starch, the Industrial Research Organization of Australia recommends 20 grams of fiber daily for digestive health. Most people only get a quarter of that amount. For the most part, the American diet is fairly devoid of resistant starch.
Can Resistant Starch Help You Lose Weight?
Since so little of the starch in resistant starch is absorbed, resistant starch has less than half the calories of standard starch. Plus, when you eat a diet rich in resistant starch, you feel less hungry. The reason? When bacteria in your intestinal tract break down resistant starch to short-chain fatty acids, the fatty acids turn on hormones like GLP-1 and peptide YY they cause you to feel full. Since resistant starch slows the absorption of whatever’s in your stomach, it helps stabilize your blood sugar so you get fewer cravings.
One study in rodents found rats that ate a diet made up of 25% resistant starch lost more body fat than those who ate an equal number of calories without consuming foods with resistant starch. Considering the calories in resistant starch are poorly absorbed and the appetite-suppressive effects that this fiber-like substance offers, it’s not a stretch to say it could help with weight control.
Other Health Benefits of Resistant Starch
Preliminary research suggests resistant starch increases absorption of minerals, including calcium, magnesium, and iron, all minerals important for health. Some plant foods contain compounds like phytates that reduce absorption of minerals while resistant starch has the opposite effect.
How to Add More Resistant Starch to Your Diet
How can you enjoy the potential health benefits of resistant starch? Add resistant starch slowly to your diet. If you’re not accustomed to it, you may experience bloating, diarrhea, and gaseousness initially, especially if you try to consume too much too quickly. A simple way to increase the amount of resistant starch to your diet is to cook, cool, and reheat potatoes and rice before serving them. This will convert a portion of the starch in these foods to resistant starch. You can do the same with beans and lentils to increase their resistant starch content.
Potato flour and green banana flour are excellent sources of resistant starch but lose some of their effectiveness when you expose them to heat. The best way to get the benefits is to add a half-tablespoon to your next healthy smoothie. Plan on feeling full afterward!
Uncooked, unrolled oats are one of the best sources of resistant starch, but you’ll also get a healthy dose when you eat whole grains like millet and barley. Choose rye and pumpernickel bread over white bread and you’ll boost the amount of resistant starch in your diet.
The Bottom Line
Resistant starch may be particularly beneficial if you have type 2 diabetes or are insulin resistant since getting more of it may help with blood sugar, and possibly, weight control, but it’s important to get some even if you’re healthy since it helps support the growth of gut-friendly bacteria that are intimately tied to overall health. As you can see, starches aren’t always the enemy, especially if they’re the resistant kind.
References:
Adv Nutr November 2013 Adv Nutr vol. 4: 587-601, 2013
Precision Nutrition. “Resistant Starch”
Optimum Nutrition 2015. “Resistant Starch: The Ultimate, Healthy Carbohydrate?”
Am J Clin Nutr. 2006 Apr;83(4):817-22.
University of Nebraska-Lincoln. “Study: Small doses of resistant starch make healthy difference”
Diabetes Care. 2006 May;29(5):976-81.
Louisiana State University. “Resistant Starch in the Diet of Rodents Promotes an Increase in Fermentation and a Reduction in Body Fat in an Animal Model of Dietary Obesity”
Pediatr Res. 1996 May;39(5):872-6.
Rocz Panstw Zakl Hig. 2007;58(1):29-34.
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