Many of us crave starch or carbohydrate rich foods but don’t want the extra calories, poor nutritional impact, or rapid glucose absorption that can cause a quick spike and then a crash as we discussed in the “hangry” post. Resistant starch is different because it offers a wide range of health benefits.
What is resistant starch?
As discussed in Consultant 360, starch provides an important source of energy for the body and has varying impacts on health depending on whether it is rapidly digestible, slowly digestible, or resistant starch. Resistant starch is a type of fiber found in certain starchy foods that resists digestion and absorption in the small intestine. Instead, it passes into the large intestine intact, and acts as food for colonic bacteria, which slowly ferment it. Compared to digestible starches, resistant starch offers the following benefits:
• It takes over 120 minutes for glucose in resistant starch to enter the blood stream. Because foods containing higher amounts of indigestible starch are digested slowly this may be a great way to improve sugar control. Clinical studies have shown that people with metabolic syndrome and insulin-resistance who consume 25-40 grams of a resistant starch fiber supplement daily experience improvements in insulin sensitivity and glycemic control as compared to those who take a placebo.
• Resistant starch provides fewer calories than other forms of starch. Since they are incompletely digested, about 2 calories of energy per gram (versus about 4 calories per gram from other starches) is absorbed. That means 100 grams of resistant starch is actually only worth 200 calories, while 100 grams of other starches gives us 400 calories. Studies have also shown digestible starches improve satiety and reduces appetite much like soluble fiber.
• Because it is fermented in the colon, it increases short chain fatty acids which are produced when the friendly gut bacteria ferment fiber in your colon, and are the main source of energy for the cells lining your colon. For this reason, they play an important role in maintaining the health of the large intestine. Animal studies suggest that because of these benefits, resistant starch may be helpful in reducing the growth of colon cancer, but there is still limited evidence in human studies. Consuming more resistant starch may also influence the composition of the microbes in the gut. Although it is not officially classified as a prebiotic, resistant starch may have prebiotic benefits, and may enhance the actions of other pre-and probiotics. They also may reduce the risk of inflammatory diseases, type 2 diabetes, obesity, heart disease and other conditions.
Sources of resistant starch
Dietary starches, such as tubers, legumes, cereal grains, and seeds, consist of either amylose (a linear molecule that is digested more slowly) or amylopectin (a branch-chain molecule that is digested more rapidly). Starches that are resistant to digestion contain a greater proportion of amylose. In general, starch-containing foods that are more highly processed, or contain more finely ground cereal grains have less resistant starch. Interestingly cooking and cooling foods such as potatoes or pasta, increases their resistant starch content.
Here are some foods that contain a high amount of resistant starch according to healthline.com:
• Oats are one of the most convenient ways to add resistant starch to your diet. 3.5 ounces (100 grams) of cooked oatmeal flakes may contain around 3.6 grams of resistant starch. Oats are also high in antioxidants and are a whole grain. Letting your cooked oats cool for several hours, or overnight, could increase the resistant starch even further.
• Rice is another low-cost and convenient way to add resistant starch to your diet. One popular preparation method is to cook large batches for the entire week. Doing this not only saves time, but also increases the resistant starch content when the rice is left to cool. Brown rice may be preferable to white rice due to its higher fiber content. Brown rice also provides more micronutrients, including manganese and magnesium.
• Several healthy grains provide high amounts of resistant starch. Although grains are often mistakenly believed to be unhealthy, natural whole unprocessed grains can be a sensible addition to your diet. Also look for grain- based foods like macaroni and spaghetti. Not only are they a great source of fiber, they also contain important minerals and vitamins.
• Beans and legumes provide large amounts of fiber and resistant starch. Both should be soaked and fully heated to remove lectins and anti-nutrients. Depending on the type of legume, they contain around 1-4 grams of resistant starch per 3.5 ounces (100 grams) after they’ve been cooked.
• Potato starch is a white powder that looks similar to regular flour. It’s one of the most concentrated sources of resistant starch, with around 72% of the starches in it being resistant. For this reason, you only need 1–2 tablespoons per day. It’s often used as a thickener, or added to smoothies, overnight oats or yogurts. It’s important not to heat the potato starch. Instead, prepare the meal and then add the potato starch once the dish has cooled. A lot of people use raw potato starch as a supplement in order to boost the resistant starch content of their diet.
• If prepared correctly and left to cool, potatoes are a good source of resistant starch. It’s best to cook them in bulk and allow them to cool for at least a few hours. When fully cooled, cooked potatoes will contain significant amounts of resistant starch. In addition to being a good source of carbs and resistant starch, potatoes contain nutrients such as potassium and vitamin C. Remember not to reheat the potatoes. Instead, eat them cold as part of homemade potato salads or other similar meals.
• Green bananas are another excellent source of resistant starch and fiber. Additionally, both green and yellow bananas are a healthy form of carbs and provide other nutrients such as vitamin B6 and vitamin C. As bananas ripen, the resistant starch transforms into simple sugars like fructose, glucose and sucrose. Therefore, you should aim to buy green bananas and eat them within a couple of days if you want to maximize your resistant starch intake.
• Hi-maize flour is often referred to as Hi-maize fiber or Hi-maize resistant starch. Like potato starch, Hi-maize flour is a very condensed form of resistant starch and can be easily added to yogurt or oatmeal. Up to 50% of it is fiber, most of which is resistant starch.
• Cooking and cooling other starches will increase their resistant starch content. As with the sources discussed above, it’s best to heat them and then allow them to cool overnight. This can be applied to most of the sources already discussed , such as rice and potatoes, as well as pasta. A one time-saving technique is to prepare a large batch of pasta, rice or potatoes on the weekend, then cool them and eat them with vegetables and proteins for complete meals during the week.
• Stale bread actually has a lot of indigestible starches and can be used in a myriad of recipes (check out a few here). Not only are you saving food but it’s healthier too.
Even though the typical United States diet is high in carbohydrates and starch, the average intake of resistant starch is only about 5 g/day, and the average intake of fiber in the United States is about 15 g/day. The national fiber recommendations are 30 to 38 grams a day for men and 25 grams a day for women between 18 and 50 years old, and 21 grams a day if a woman is 51 and older. Another general guideline is to get 14 grams of fiber for every 1,000 calories in your diet. Achieving these goals is beneficial to your overall health, and fiber helps you feel fuller, longer. Because many foods that are good sources of resistant starch are also high in fiber, incorporating more high-fiber beans, seeds, and even an occasional under-ripe banana, will also increase intake of resistant starch. Although there is no recommended amount, studies suggest approximately 20g of resistant starch each day is needed to achieve the potential health benefits.
A study in the Nutritional Journal looked at the benefits of indigestible starches. In particular, researchers looked at barley kernels, which are high in fibrous materials and resistant starches. They believed incorporating indigestible starches into a diet could have far-reaching and long lasting effects. To prove this, they had some subjects consume barley kernels while a control group did not. Then tested participants’ blood after several meals, into the next day. They discovered that indigestible carbohydrates improved glucose control, showing better blood sugar stability for up to sixteen hours after eating the barley kernels. They also had decreased signs of inflammation, fewer circulating free fatty acids, and felt less hunger the following day eating less at breakfast, and even less at lunch.
There’s no question that resistant starches help to stabilize glucose control, improve satiety, decrease caloric intake and improve colonic health- all powerful tools to add to anyone’s nutrition and weight loss program.
-Dr. Courtney