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Why do you need more plantains in your life, you ask? Not only are they delicious, but they also contain a specific type of dietary fiber called resistant starch (RS). RS has been a hot topic in research lately because it may protect against colon cancer, diabetes, and even help with weight management. Additionally, RS provides food for your gut microbes, which in turn benefits your digestive tract. In this post, I’ll tell you about what foods contain RS as well as leave you with a recipe so that you can add more plantains to your life.
Most people know to eat fiber when they are constipated, but what is fiber exactly? Dietary fiber constitutes a family of compounds that originate from plants and are not digested by humans. In 2002, the US Institute of Medicine added “functional fiber” to this family to designate the roughage that has health benefits in humans (1). RS is not broken down in the stomach and absorbed in the small intestine, but instead it is fermented by the gut microbes in your colon. The resulting compounds play a variety of beneficial roles, including providing energy to the cells that line your intestines. Therefore RS is considered a type of functional fiber.
There are five different types of resistant starch that differ by their 3-dimensional structures and/or their origin. Most of the RS are created by nature and are found in starchy foods such as cereal grains or seeds (type 1), uncooked potatoes and green bananas (type 2), and cooked and cooled starches like rice (type 3). Type 4 RS is artificially made by a chemical reaction and is mainly found in processed foods. The last type of RS (type 5) is also au naturel, and is formed when fats stick to starch molecules to form complexes. Below you will find a table summarizing the different types of RS and their common food sources.
Microbial degradation of RS in your colon produces a number of compounds including gases (think farts) and short chain fatty acids (SCFAs). The SCFAs acetate, proprionate, butyrate and valerate are used as fuel by your intestinal epithelial cells (2). These compounds can influence the pH of the gut and thereby affect which microbes are present, as not all bacteria tolerate acid equally (3). Only specific types of bacteria can degrade RS, so consuming this fiber also selects for the species that contain the proper enzymes. By eating foods with RS, you are not only creating an environment that is preferential to specific beneficial bacteria, but these microbes will turn the fiber into molecules that help your gut.
Research has shown that the bacterial fermentation products of RS may help to protect against colorectal cancer. Most of these studies used animal models or cells grown in a test tube to try to understand the mechanism of protection. For example, the SCFA butyrate has antitumor properties in cell culture studies (4). Although fewer studies have been performed in humans, scientists recently determined that RS supplementation to a diet high in red meat reduced markers of colorectal cancer (5). Further research is needed in order to better understand how RS may protect against colon cancer, but the evidence is mounting that this functional fiber plays a role in maintaining colonic health.
RS may mitigate some of the risk factors associated with diabetes, and particularly type 2 diabetes. Foods high in resistant starch often have a low glycemic index, meaning that they do not significantly elevate your blood glucose level. This property is particularly important for people with type 2 diabetes because their disease inhibits their bodies’ ability to uptake glucose into their cells and therefore they should not consume foods that release large amounts of glucose. Consuming foods high in RS may also help to reduce blood glucose levels in subsequent meals, as shown by a study in which consumption of high-amylose starch at breakfast reduced the glycemic response after eating a lunch with readably digestible starches (6). Therefore the benefits of eating foods high in RS may last beyond the meal in which it was consumed.
Even if you aren’t worried about colon cancer or diabetes, RS may help with weight management, which is a common goal in our society. RS has a lower energy density than that of other carbohydrates and therefore when substituted into a diet, results in less calorie consumption. Eating RS may make people feel more full, however, the evidence supporting this hypothesis is not very clear. For example, one study fed its participants 25 g of type 3 resistant starch with breakfast and found no impact on calorie intake or satiety for the rest of the day (7). In contrast, another group fed lean and overweight men and women either 20 or 30 g of a mixture of type 1, type 2, and viscous fiber in a smoothie with breakfast and found that the 30 g dose improved satiety until after lunchtime and decreased food intake at dinner (8). Perhaps the differences in these results are due to the fact that different types of resistant starches were used. Nonetheless, adding RS to your diet will benefit your health, but may not necessarily help you lose weight.
So what foods contain resistant starch, you ask? Check out the following table to find out:
On a family trip to Belize last year, I discovered a meal that is both high in resistant starch and delicious! At a quaint outdoor cafe in Placencia, we were served the breakfast of the day: beans, rice, fried plantains, and two eggs. If you were feeling spicy, you could sprinkle on one of their habanero hot sauces. It was amazingly simple, but very satisfying and delicious. I have been recreating the dish at home to stir memories of the Caribbean. Here’s the recipe to try it out for yourself:
Beans & Rice with Fried Plantains and Eggs
Makes enough for 4-6 people
Ingredients
1 can black beans rinsed and drained (you can use any beans you desire)
2 c cooked rice (white or brown) and if you’re feeling fancy, add tomatoes and spices to your rice while cooking
2 very ripe plantains (to the point that they are almost completely black in color)
2 eggs/person
Several tbsp of your favorite cooking oil
Peel the plantains and slice them roughly ¼ inch thick. Heat several tbsp of oil in a large skillet over medium low heat. When the oil is warm, place the plantain slices in the skillet. After several minutes, check to see whether they have browned. If so, flip and cook until browned on the second side. The plantains are properly cooked when they start to take on a translucent tint. Remove the slices from the pan. Repeat until all of the plantains are cooked. Heat another few tbsp of oil in the skillet and add the beans and cooked rice. Stir occasionally, and cook the beans and rice until heated through, then add the plantains back to the pan. Turn heat to low until the food is ready to eat.
In a separate apparatus, cook 2 eggs/person in your favorite fashion - scrambled, fried, over easy, etc.
Plate the eggs on top of the rice, beans, and plantain mixture. Serve with your favorite hot sauce (preferably one of Marie Sharp’s Belizean products). Enjoy!
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References and Further Reading
- Macfarlane S, Macfarlane GT. Regulation of short-chain fatty acid production. 2003. Proc Nutr Soc 62:67–72
- Fung KY, et al. A review of the potential mechanisms for the lowering of colorectal oncogenesis by butyrate. 2012. Br J Nutr 5:820-31
- Humphreys KJ, et al. Dietary manipulation of oncogenic microRNA expression in human rectal mucosa: a randomized trial. 2014 Cancer Prev Res (Phila) 8:786-95
- Klosterbuer AS, et al. Resistant starch and pullulan reduce postprandial glucose, insulin, and GLP-1, but have no effect on satiety in healthy humans. 2012. J Agric Food Chem 48:11928-34
- Harrold J, et al. Satiety effects of a whole-grain fibre composite ingredient: reduced food intake and appetite ratings. 2014. Food Funct 10:2574-81
- Murphy MM, et al. Resistant starch intakes in the United States. 2008. J Am Diet Assoc 108:67–78.
Nice Review Papers on Resistant Starch
Raigond P, et al. Resistant starch in food: a review. 2014. J Sci Food Agric. doi: 10.1002/jsfa.6966
