Diabetes – An Overview
Diabetes is a chronic disease that impacts the amount of sugar in the blood. This is due to a breakdown in the body’s ability to use and/or produce insulin. Insulin is a hormone that is produced by the pancreas and acts as a key to unlock the doorway to the body’s cells and tissues to allow sugar into those cells to be utilized as energy. When the pancreas does not make enough insulin, or the body does not use insulin effectively, the body’s blood sugar rises to levels that are higher than normal.
The prolonged exposure to high blood sugar levels in the body can lead to serious long-term complications such as:
- Neuropathy (loss of sensation commonly experienced in the hands, fingers, toes, and feet)
- Retinopathy (blurriness, dark areas of vision, difficulty perceiving color, and blindness)
- Cardiometabolic health complications (stroke, mini-stroke, and heart attack)
- Renal disease (decline in kidney function causing swelling of the legs, puffiness around the eyes, nausea, vomiting, frequent urination, loss of appetite, easy bruising)
- Amputation (removal of affected limbs due to infection/necrosis stemming from neuropathy or poor circulation, particularly in the hands and feet)
- Dental issues (losing teeth).
It is often suggested to patients with a diagnosis of diabetes that they work to make behavioral and lifestyle changes that can positively influence their disease outcomes. This can include diet, exercise, stress management, healthy coping strategies, and behaviors such as monitoring blood sugar and taking medicine as prescribed. All these efforts can reduce the potential long-term impacts of diabetes and support individuals with this diagnosis in living long, healthy lives.
Nutrition and Diabetes
The sugar that the body uses as energy comes from the food that an individual consumes, specifically carbohydrates. For those with diabetes, carbohydrates can be a concern as they are the macronutrient specifically responsible for an increased blood sugar response. In the case of individuals living with a diagnosis of diabetes, they are recommended to focus on consuming complex carbohydrates. Complex carbohydrates are often defined as containing multiple sugar molecules that are strung together and are, therefore, digested more slowly due to their diverse nutrient content, which often includes fiber. The presence of fiber and other essential nutrients helps to stabilize and balance blood sugar, which provides sustained energy over a longer period and is often associated with better, long-term blood sugar outcomes for patients with diabetes.
Some examples of complex carbohydrates include:
- Whole grain bread
- Whole grain pasta
- Brown rice
- Non-starchy vegetables (leafy greens, tomato, carrot, peppers, broccoli, cauliflower, summer squash, waxy beans, asparagus, mushrooms, radishes, etc.)
- Legumes (beans, peas, and lentils).
On the other hand, some carbohydrates have a “simpler structure”, meaning that they can raise blood sugar levels rapidly because the body is able to digest them faster than complex carbohydrates. When one compares simple carbohydrates to complex carbohydrates, on a chemical level, simple carbohydrates are made up of one to two sugar molecules, which are great at providing quick energy. This may be needed for someone with diabetes to treat a low blood sugar (blood glucose level under 70 mg/dL). However, for the purpose of sustaining energy over time, simple carbohydrates are often associated with blood sugar spikes and, later, energy crashes that can leave one feeling sluggish and unwell.
Some examples of foods high in simple carbohydrates include:
- Sweet pastries
- Desserts
- Processed snacks
- Honey
- Table sugar
- Enriched grains (white bread, pasta, and rice)
While individuals with diabetes must be aware of how many grams of carbohydrates they are consuming during mealtimes, it is not recommended to remove or eliminate them from the diet. Sugar, glucose being the most common form of sugar in the body, is the building block of carbohydrates and is the body’s preferred form of energy. Therefore, it is important to maintain a healthy relationship with foods that contain carbohydrates. For the past 50 years, research has explored a unique food preparation method involving carbohydrates, especially as it relates to those living with a diagnosis of diabetes. This research focuses on a phenomenon called starch retrogradation, and for some, this can be an interesting addition to healthy mealtime practices that may positively influence post-meal blood sugar readings and outcomes when choosing to sit down to a starchier meal, such as a bowl of pasta, a side of rice, or potatoes.
Understanding Starch
Starch is a component of foods such as pasta, rice, and potatoes. Starches are a type of complex carbohydrate, which means that they are comprised of many individual sugar molecules that are strung together to make a chain. Certain kinds of starches have longer chains than others, taking more time to break down and digest. This can result in a slower or more gradual increase in blood sugar levels, which is ideal for an individual who has a diagnosis of diabetes. The foods previously mentioned – pasta, rice, and potatoes – contain a high starch content, meaning they have many of these long sugar chains present. However, in the case of rice or pasta, if one chooses the refined version of these foods (white rice or white pasta), there are more shortened starch chains that have a simpler structure, which is easier to digest and can result in a more rapid blood sugar response. Other starchy foods include beans, green peas, corn, and winter squash, as well as unripe bananas, plantains, dates, and some varieties of apples.
These starchy foods differ from vegetables that are much lower in starch and total carbohydrates, which we refer to as non-starchy vegetables. Non-starchy vegetables have less of a blood sugar-elevating impact. Examples of non-starchy vegetables include lettuce, cucumber, tomatoes, peppers, carrots, cabbage, broccoli, and cauliflower.
Starchy foods can be further categorized into three subgroups, which represent how the starches on which they are built behave during metabolism: rapidly digestible starch, slowly digestible starch, and resistant starch.
Rapidly Digestible Starches
Rapidly digestible starches are typically found in highly processed foods and trigger a blood sugar-elevating response and insulin release within 20-30 minutes of consumption. Foods which contain this particular kind of starch include processed snacks, refined grains such as white bread, rice, and pasta, and sweet treats such as pastries, pie, and cakes.
Slowly Digestible Starches
Next, slowly digestible starches take longer to break down than rapidly digestible starches and typically include greater amounts of fiber, which is a nutrient that inhibits the starch molecules from digesting too quickly. This, in turn, slows an individual’s blood sugar rise and insulin response, leading to more balanced and sustained blood sugar readings over time. Foods that contain slowly digestible starches include whole grains, legumes, and starchy nuts such as peanuts and cashews.
Resistant Starches
Lastly, resistant starches are defined as a type of starch molecule that resists the process of digestion. Because of this, the starch molecules cannot break down and, therefore, cannot elevate blood glucose. The process of digestion involves many different organs and bodily functions; however, we see the most digestion activity occurs when our food reaches the small intestine. This is where nutrients are absorbed by our body, including sugar. In the case of resistant starch, the resistant starch molecules are not broken down and absorbed in the small intestine but instead move to the large intestine, where they are fermented and turn into food for our beneficial gut bacteria. Thus, resistant starch is often considered a prebiotic, meaning that it is food for our healthy gut bacteria. However, overconsuming foods with resistant starch can lead to potential digestive discomfort such as gas, bloating, and diarrhea. So, like with all foods, it is important to consume these in moderation. Some foods that have high levels of resistant starches include potatoes, green bananas, legumes such as lentils, beans, and chickpeas, and cooked and cooled starches such as rice and pasta.
Starch Retrogradation Explained
Starch retrogradation is a phenomenon by which cooked starch molecules become gelatinized in the presence of water, cool completely, and recrystallize to create stronger, more structured starch molecules that are harder for the body to digest. It starts by cooking rice, potatoes, or pasta, where the starch molecules swell and begin breaking down into a simpler structure. After cooking, these starchy foods can then be cooled to a safe temperature before being placed in the refrigerator for 12-24 hours. However, it is important to note that these foods must be given ample time to cool completely.
Research suggests that the starch retrogradation process is most pronounced when foods are exposed to and allowed to cool to a temperature of 40°F or cooler for at least 24 hours. During this time, the starch retrogradation process takes place, changing and altering some of the starch molecule chains that would be responsible for quickly impacting blood sugar into resistant starch. Resistant starch molecules have more rigid and structured bonds – it is comparable to two individuals holding hands versus those same two individuals holding hands and interlocking fingers. Just like it is harder to let go of or disconnect interlocked fingers, the same can be said for the digestion of resistant starch – it is harder to break the bonds connecting the sugar molecules that make up the starch chain, preventing rapid digestion from occurring. The food (rice, pasta, or potatoes) can then be reheated and consumed the day after cooking.
Many individuals with diabetes who follow this process report that they notice a more gradual increase in their blood sugar after a meal, and that the rise that they do experience is not as significant compared to eating the starchy food on the same day of cooking. However, it is important to note that each individual with diabetes has a unique experience, and no two individuals will react to foods, medicines, or other behavioral strategies in the same way. The same can be said for a process like starch retrogradation; it may be a beneficial approach to implement for some, but others may not experience the same blood sugar benefits. However, given that this is a safe process to implement (as long as food is being handled safely and cooled properly), it may be a worthwhile process to experiment with during mealtimes. It may also be beneficial to talk to a registered dietitian or a clinician overseeing care to ensure that this method does not disrupt other necessary self-care practices.
Benefits of Resistant Starch
There are many short-term and long-term benefits associated with resistant starches. A major short-term benefit for someone with a diagnosis of diabetes is the reduction in postprandial (post-meal) blood sugar rise. In a 2021 meta-analysis published in The American Journal of Clinical Nutrition, 745 potential articles and 25 randomized crossover trials were reviewed; and results from the analysis demonstrated that there was a significant decline in blood sugar rise and subsequent insulin secretion post-mealtime caused by foods that contained higher levels of resistant starch. Additionally, another study looking at the impact on post-meal blood sugar rise amongst individuals with type 1 diabetes using the starch retrogradation method, which focused on cooked and cooled rice, also demonstrated an association with a lowered post-meal blood sugar response. However, it should be noted that in this same study, the starch retrogradation method did increase the risk of a post-meal hypoglycemic episode (low blood sugar) when using and administering insulin. This association is likely due to the alteration of the starch structure, creating a more rigid bond as previously mentioned, which inhibits the quick digestion of the starch chain into its simpler, individual sugar molecules. As a result, in this particular study, insulin dosage was adjusted for patients consuming the cooked and cooled rice to account for the slower and less noticeable blood sugar rise. The benefit of the improved blood sugar control on a longer-term scale could include a reduction in hemoglobin A1C, which may directly correlate to a reduction in the longer-term complications often associated with diabetes that were mentioned earlier, such as neuropathy, retinopathy, kidney disease, dental issues, and cardiometabolic health outcomes.
Secondary to the improvement in blood sugar control for individuals with both type 1 and type 2 diabetes, it is noted that the implementation of the starch retrogradation process via cooking and cooling one’s starchy foods may increase feelings of post-mealtime satiety (that is, feelings of satisfaction and fullness). This can support prolonged energy balance, which could potentially aid in achieving and/or maintaining a healthy weight. According to a report published in Obesity, modest weight loss of 5-10% of one’s total body weight can help lower blood pressure, cholesterol, and daily blood sugar levels, and improve overall heart health. For an individual with diabetes, these outcomes can be significant, as diabetes can increase the risk for cardiovascular disease.
How to Use Starch Retrogradation in Everyday Meal Preparation
The process of starch retrogradation is simple: cook and cool your starchy foods. Regarding pasta, potatoes, and rice, boil or cook the starchy food of choice according to package instructions or by standard practice. These foods should have a minimum temperature of 135°F when cooked and can then be cooled to a temperature of roughly 70°F within 2 hours of cooking. This protocol is indicative of proper food safety handling for Time/Temperature Controlled for Safety according to the Food and Drug Administration’s standards. The easiest way to accomplish this is to portion your foods out into individual containers or in a longer, shallower pan, which allows for more rapid heat release and transfer. From there, continue to cool the cooked food for 4 hours until it reaches a temperature below 41°F. If using the refrigerator to accomplish this second step of cooling, work to ensure that the containers have a way to vent the heat from the food and arrange the containers in a way to maximize the heat transfer.
It is important to allow these foods to cool completely; the longer they have time to cool, the more structured the resistant starch bonds become, increasing the impact of this process on blood sugar control and outcomes. When it is time to eat, reheat the portion of potatoes, rice, or pasta to a temperature of 165°F and enjoy in whatever manner one chooses. The reheating of the food will not decrease the amount of resistant starch present.
Conclusion
The process of starch retrogradation is a fascinating phenomenon that can be implemented for potentially enhanced blood sugar control. However, as previously mentioned, this is not a process that works universally for all. With that said, as long as food safety considerations are taken into account when cooking and cooling the chosen food, this can be a safe and easy mealtime practice to try the next time one wants to cuddle up on the couch with a bowl of pasta, rice, or potatoes.
References:
- Chakraborty, I., Govindaraju, I., Kunnel, S., Managuli, V., & Mazumder, N. (2023). Effect of Storage Time and Temperature on Digestibility, Thermal, and Rheological Properties of Retrograded Rice. Gels (Basel, Switzerland), 9(2), 142. https://doi.org/10.3390/gels9020142
- Tahrani AA, Morton J. Benefits of weight loss of 10% or more in patients with overweight or obesity: A review. Obesity (Silver Spring). 2022; 30: 802–840. doi:10.1002/oby.23371
- Strozyk, S., Rogowicz-Frontczak, A., Pilacinski, S., LeThanh-Blicharz, J., Koperska, A., & Zozulinska-Ziolkiewicz, D. (2022). Influence of resistant starch resulting from the cooling of rice on postprandial glycemia in type 1 diabetes. Nutrition & diabetes, 12(1), 21. https://doi.org/10.1038/s41387-022-00196-1
- Kim, M. K., Park, J., & Kim, D. M. (2024). Resistant starch and type 2 diabetes mellitus: Clinical perspective. Journal of diabetes investigation, 15(4), 395–401. https://doi.org/10.1111/jdi.14139
- Cai, M., Dou, B., Pugh, J. E., Lett, A. M., & Frost, G. S. (2021). The impact of starchy food structure on postprandial glycemic response and appetite: A systematic review with meta-analysis of randomized crossover trials. The American Journal of Clinical Nutrition, 114(2), 472–487. doi:10.1093/ajcn/nqab098
- Kristine Dilley. (2024). Does cooling starchy food after cooking really lower its calories. Retrieved from https://health.osu.edu/wellness/exercise-and-nutrition/cooling-pasta-changes-starch#:~:text=So%2C%20a%20portion%20of%20the,glucose%20after%20you%20eat%20it
- Li, C. (2024). Unraveling the complexities of starch retrogradation: Insights from kinetics, molecular interactions, and influences of food ingredients. Food Reviews International, 40(9), 3159–3182. doi:10.1080/87559129.2024.2347467
- The Johns Hopkins Patient Guide to Diabetes. (2020). What is resistant starch? Retrieved from https://hopkinsdiabetesinfo.org/what-is-resistant-starch/
- The U.S. Food & Drug Administration. (2024). Cooling cooked time/temperature for controlled for safety foods and the FDA food code: For food employees. Retrieved from https://www.fda.gov/media/181882/download
- The University of Sydney. (2021). Nutritional qualities of starch depend on the way it is digested. Retrieved from https://www.sydney.edu.au/science/news-and-events/news/2021/12/20/nutritional-qualities-of-starch-depend-on-the-way-it-is-digested.html
Authors:
- Julianna Lyle, Rural Health and Nutrition Agent, Anderson County
- Hannah Wilson, PhD, Assistant Professor, Community Nutrition, Department of Food, Nutrition, and Packaging Sciences
- Jenna Lynes, Graduate Student Intern, Rural Health and Nutrition
- Jessica Lynes, Graduate Student Intern, Rural Health and Nutrition
