The blood sugar benefits of type 2 resistant starch (rs2) RHONDA S. WITWER Ingredion Incorporated, 10 Finderne Avenue, Bridgewater, New Jersey 08807, USA Rhonda S. Witwer KEYWORDS: blood sugar; metabolism; insulin resistance; resistant starch; type 2 diabetes; sensory. ABSTRACT: Consumers are concerned about the impact of carbohydrates on their blood sugar levels. While there has been considerable discussion on the post-prandial glycemic response of foods, the research has been chronically inconsistent in confirming potential health benefits. In contrast, insulin sensitivity is directly connected to maintaining healthy blood sugar levels. This review will profile the evidence demonstrating that type 2 resistant starch from high amylose corn is ideal for formulating foods to help people manage their blood sugar levels. It has a reduced post-prandial glycemic response, it significantly improves insulin sensitivity and blood sugar metabolism, it replaces flour in formulations while maintaining the taste and textures that consumers prefer and it can be used as a supplement to the diet. The market for foods that help manage blood sugar levels is signals the tissues that glucose is available as energy and emerging. The low carbohydrate diet fad of ten years ago helps to prevent fat from being burned and released out of was a major shock to the food industry that carbohydrates storage. In individuals with healthy metabolism, this works and their impact on weight and blood sugar levels were very well. The muscles and tissues are sensitive to the insulin important to consumers. While the food industry focused and respond by transporting glucose quickly. However, on whole grains in the intervening decade, consumers these metabolic systems can lose their fl exibility and cease Food technologies ingredients to improve consumer's perception did not forget about the importance of their blood sugar to work well, a process that can develop over many years. levels and many continued to avoid carbohydrate-rich foods. Recently, 26% of American primary grocery shoppers The muscles and tissue within the body may begin to reported that they had decreased their consumption of resist the effects of insulin, which is called loss of “insulin carbohydrates within the past two years, according to the sensitivity”. This is accelerated in individuals that are 2013 HealthFocus Trend Survey. In addition, Euromonitor genetically predisposed or who are overweight and reports that retail volume of baked goods are expected to commonly occurs with aging. For insulin resistant individuals decline by 3% in the US market between 2011 and 2016 (1). to maintain control over blood glucose levels, their pancreas releases higher levels of insulin. First, post-prandial While the larger, mainstream markets are struggling to insulin responses spike higher and higher but fasting and grow, innovative companies are venturing into new post-meal glucose levels remain normal. Over time, as vol 24(3) - May/June 2013 - business development in foods that help manage blood insulin resistance increases, fasting insulin levels also start sugar levels. For instance, “Made for You Foods”, in to rise. Eventually, the pancreas is damaged by the high Australia, sells frozen meals that are levels of glucose or simply cannot produce more insulin designed “for people watching their and it starts to fail, resulting in less insulin production. At blood sugar”. Their message is this point, the body starts to lose control of its glucose and reinforced by a “D-tick” logo, blood glucose levels start to rise. All of these changes in which Made For You Foods metabolism are generally invisible, as doctors routinely created to signify that it meets monitor only blood glucose levels and not insulin levels. It FOOD Industry Hi Tech the Australian Diabetes Council’s has been estimated that by the time an individual has been nutrient criteria. It focuses on diagnosed with type 2 diabetes, they have lost 50-80% of Agro delivering portion-controlled foods their insulin-production capabilities (beta-cell function) (2). with a reduced post-prandial glucose response. According to the International Diabetes Federation, more than 371 million adults are already living with diabetes, which represents more than 8% of the global population BACKGROUND (3). This number is projected to increase to 552 million people by 2030, or 9.9% of adults, which equates to After people eat food, the carbohydrates in that food approximately three more people with diabetes every 10 are digested and broken down to the glucose, which are seconds. Diabetes caused at least USD 471 billion dollars in absorbed and cause an increase in glucose (sugar) in the healthcare expenditures in 2012; 11% of total healthcare bloodstream (called post-prandial glucose response). If expenditures in adults (20-79 years). The expense is the carbohydrates are slowly digested or resist digestion, staggering and is rapidly climbing. the rise is slow and gradual. If, however, the carbohydrates are easily digested, the rise is steep and fast. In response to Within the United States, the Centers for Disease Control the glucose surge, the pancreas releases insulin to assist in report than 33% of American adults have prediabetes (4), moving glucose from the blood stream into muscles, tissues which is defi ned as fasting blood glucose levels between and the brain, where it is utilized as energy. Insulin also 100 mg/dl and 126 mg/dl. In short, blood glucose levels are 34 higher than normal (£ 100 mg/dl) but not yet high enough glycemic response when standardized to the quantity to be classifi ed as type 2 diabetes (≥126 mg/dl). of “available” or “glycemic” carbohydrates. In 2011, The Food technologies ingredients to improve consumer's perception Unfortunately, less than 10% know that they have European Food Safety Authority (EFSA) approved a claim prediabetes (5). that resistant starch reduced the post-prandial glycemic response when it substituted for a minimum of 14% of the Maintaining healthy blood sugar levels are important not digestible starch (17). only for type 2 diabetes, it appears to be important for More importantly, type 2 resistant corn starch also other diseases as well. Insulin resistance is an underlying signifi cantly impacts long-term blood sugar metabolism. risk factor in Metabolic Syndrome (6), which doubles the Six clinical studies have shown that it signifi cantly improves risk of developing cardiovascular disease. In addition, insulin sensitivity (18-23). Lower insulin levels are found after researchers are investigating Alzheimer’s Disease as a only 30 minutes ((24). Similar benefi ts have been found possible type 3 category of diabetes as insulin sensitivity in healthy individuals, individuals with insulin resistance, is critically important in the progression of both types of overweight individuals and individuals with type 2 diabetes. diseases (7). A 2012 study found that three tablespoons of Type 2 resistant corn starch added as a supplement to the diet increased insulin sensitivity in overweight men by 56% (21). CONSUMERS ARE CONCERNED ABOUT MANAGING THEIR The benefi t is believed to be similar in women (even though BLOOD SUGAR this particular study did not show it) as prior studies also found improved insulin sensitivity in women. Consumers around the world are already concerned about One recent clinical study demonstrated that dietary the health impact of carbohydrates. According to recent consumption of RS2 resistant corn starch also shifted fat HealthFocus International trend surveys, Spanish grocery storage within adipose tissue (19). It has been reported that shoppers may be the most concerned, as 42% of Spanish individuals with type 2 diabetes and/or obesity have low shoppers report that “low carbohydrate” is an extremely levels of key lipases in their adipose tissue (26, 26). These or very important label claim and 27% always or usually lipases are responsible for properly storing fat. If storage follow a low carbohydrate/high protein diet. The US is not mechanisms are not working well in lipase tissue, the fat far behind, with 33% of grocery shoppers reporting that circulating in the blood is eventually improperly stored in “low carbohydrate” is an extremely or very important the muscle, the pancreas and the liver, where it directly label claim and 23% of primary grocery shoppers always or causes increases in insulin resistance. Increasing the lipases usually choosing foods to manage their blood sugar levels. in adipose tissue may help to break the vicious cycle linking In addition, 32% of American shoppers decreased their fat with rising insulin resistance. Dr. Denise Robertson fed consumption of sugar within the past two years. obese men and women with insulin resistance RS2 resistant corn starch and demonstrated clear stimulation for key lipases within the adipose tissue, which are responsible REDUCING THE POST-PRANDIAL GLYCEMIC RESPONSE for fat storage. This shift in fat storage contributes to Agro maintaining healthy blood sugar metabolism. There is general consensus about glycemic and weight Animal studies have also shown delayed onset of insulin FOOD Industry Hi Tech benefi ts of eating foods with a lower post-prandial resistance (27). One recent animal study found improved glycemic response, especially for diabetics (8, 9). However, functioning and preservation of the beta-cells within the benefi ts in healthy populations are less certain: some the pancreas (which produce insulin) as well as inter- reviews have demonstrated benefi ts (10-12), while other generational blood sugar benefi ts (28). reviews have shown benefi ts in some populations but not others (13) or have been inconclusive (14). One of the major issues is that it has been very diffi cult to isolate the RS2 RESISTANT CORN STARCH FUNCTIONAL - impact of lower post-prandial glycemic response of foods CHARACTERISTICS vol 24(3) - May/June 2013 without also at the same time increasing the quantity of non-digestible carbohydrates. If the benefi ts are actually RS2 resistant corn starch is a white, fi ne corn starch with due to the non-digestible carbohydrates instead of the a bland fl avor and low water-holding capacity.