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Sweeteners
Sweeteners are categorized as nutritive (containing calories) and nonnutritive (non-caloric). Different sweeteners can have different effects on blood glucose levels.
Nutritive Sweeteners
For many years, the common nutritive sweetener, sugar (sucrose), was excluded from diabetes meal plans in order to avoid the significant postprandial excursions in glucose levels that it might cause, as well as to reduce the caloric intake of those hoping to lose weight. Other nutritive sweeteners that did not cause such postprandial excursions, as well as non-nutritive sweeteners, replaced this sugar. However, as more was learned about the true glycemic indices of various foods, both alone and in combinations, the concerns over the hyperglycemic effects of sucrose lessened. Further, people who selected alternative nutritive sweeteners, thinking that the "sugar-free" designation would allow unlimited consumption soon learned that "sugar-free" does not mean "carbohydrate free!"
All nutritive sweeteners must be included in daily carbohydrate allotments. Commonly used nutritive sweeteners in addition to sucrose include the sugars fructose and dextrose, as well as honey, corn syrup and molasses. All of these substances contain the same number of calories per gram (4), and, in significant amounts, all can elevate the blood glucose level.
The sugars in common usage consist of six carbon atoms or hexoses. One of these sugar molecules is called a "monosaccharide," while two bonded together are a "disaccharide." Glucose and fructose are monosaccharide hexose sugars. Sucrose, a disaccharide made up of glucose and fructose, is the most common sweetener used by manufacturers to sweeten their products and the one that those with diabetes have tried hardest to avoid.
Recently, as a result of improved understanding and better treatment tools, sucrose has been included as part of the medical nutrition therapy prescription. Properties such as the bulking effect of sugar, which is lacking in non-nutritive sweeteners, make it difficult to eliminate entirely in some recipes. Also, sucrose when combined with other ingredients high in fat, such as in ice cream, may not cause an overwhelming glucose elevation in the immediate postprandial period. In addition, with rapid acting insulins, as well as antidiabetes mediations that specifically stimulate postprandial insulin release, the insulin effect can now be more focused during the postprandial period. Some sucrose may be allowed as part of the carbohydrate content of a full meal (or as dessert). Calories still count, however, and for those on weight-loss diets, extra calories such as those in dessert-type foods are not advisable. If such foods are eaten, the usual recommendation is to have the patient carefully monitor postprandial glucose excursions and, with the help of a dietitian or other provider, develop his or her own medication adjustment scale for such foods.
Fructose (or "fruit sugar" or "levulose") is found in fruits and honey, and is approximately 1.2 times as sweet as sucrose. Fructose plus glucose make up sucrose. Fructose is absorbed into the bloodstream more slowly than sucrose and appears to cause a slower rise of the blood glucose level for a given concentration of calories in persons with well-controlled diabetes. It's metabolized in the liver and, unlike other sugars, does not require insulin for utilization by the body. However, people who have high blood glucose levels due to insufficient insulin convert fructose to glucose, which results in a further rise in blood glucose level. Fructose may also worsen pre-existing problems with hypertriglyceridemia. The routine use of fructose as a substitute for sucrose in small quantities such as in cooking and baking is reasonable.
The sugar alcohols are basically sugar molecules converted to their alcohol form. Commonly used sugar alcohols include sorbitol, xylitol, mannitol, and hydrogenated starch hydrolysates. These substances contain approximately 2 calories per gram. Compared with glucose and sucrose, they are not completely absorbed and thus cause less postprandial hyper-glycemia. But herein lies the problem, as well. Poor absorption can result in an osmotic diarrhea when these substances are consumed in large quantities (over 30 grams daily), although some patients will experience diarrhea, cramps and gas with smaller amounts. Sorbitol, for example, is found in many products such as ice cream, chewing gum, and "sugarfree" candy and baked goods. A key education point concerning foods containing sugar alcohols is that these "sugar-free" foods still contain carbohydrate -- sometimes as much as the regular version, as well as calories and fat, and thus need to be counted in the diabetes meal plan.
Non-nutritive Sweeteners
Non-nutritive sweeteners provide almost no calories and do not affect blood glucose levels. These include:
- Aspartame: Nutrasweet, Equal, Sweet Mate
- Saccharin: Sucaryl, Sugar Twin, Sweet Magic, Sweet 'n Low
- Acesulfame-K: Sunette, Sweet One
- Sucralose: Splenda, Nevella
- Stevia: PureVia, Truvia, Stevia Extract In the Raw, Only Sweet
Artificial sweeteners have improved the quality of life for many people with diabetes and those who are trying to lose weight. All of the nonnutritive sweeteners have undergone the FDA's rigorous safety testing.
Saccharin is 375 times sweeter than sucrose by weight. It has been available for some time, as it was first developed in the late 19th century. Until the advent of aspartame, saccharin was the leading non-nutritive sweetener, used in many soft drinks and as a tabletop sweetener, although many people complain that it has a displeasing aftertaste. A study suggesting a higher incidence of bladder cancer in animals given saccharin led to a reduction in saccharin use several years ago. However, these animals were fed very large and unrealistic doses of it, and there is no evidence of a cancer risk in humans. In 2000, saccharin was dropped from the FDA's cancer-causing chemical list.
Aspartame is considered a non-nutritive sweetener. Although it does contain 4 calories per gram, it is 180 times as sweet as sucrose, and it is effective in such tiny doses that it essentially has no real caloric value. Aspartame is made synthetically from the two naturally occurring amino acids aspartic acid and phenlyalanine. As it is made from phenylalanine, people with phenylketonuria (PKU) who cannot metabolize phenylalanine should avoid aspartame.
The Food and Drug Administration approved the use of aspartame in 1981. It is found in numerous products from cereals to soft drinks to chewing gum and does not have the same aftertaste as saccharin. It is added to products under the brand name Nutrasweet, while the tabletop form is marketed as Equal. Equal contains some added dextrose and dried corn syrup to allow its granular form to flow. Each packet is as sweet as 2 teaspoons of sugar, and provides 4 calories (compared with 32 calories for 2 teaspoons of table sugar). Aspartame is unstable at high temperatures and loses its sugar-like sweetness, so it is usually not used during the cooking process.
Aspartame has also faced some controversy. While extensive studies have not shown aspartame to be toxic, there have been a few reports that in some persons it may trigger migraine headaches or diarrhea. Some people are "sensitive" to aspartame, and even small quantities make them feel uncomfortable; thus they must be cautious in selecting commercially prepared foods to avoid aspartame. Fortunately, these complications appear to be relatively rare. Nevertheless, recommendations by both the ADA and the FDA suggest limiting the daily intake of aspartame to 23 mg per pound of body weight (50 mg/kg). For a person weighing 150 pounds, this would be about 3400 mg daily, a difficult amount to consume when you consider that one can of diet soda contains 170 to 200 mg of aspartame and that a packet of Equal contains 35 mg of aspartame. It should be noted that several health groups, including the American Medical Association, the American Diabetes Association, and the American Academy of Pediatrics Committee on Nutrition, have issued statements in support of aspartame's safety.
Acesulfame K. (acesulfame potassium) is a sweetener approved by the FDA in 1988 that is approximately 200 times sweeter than sucrose. It is derived from acetoacetic acid and chemically resembles saccharin. Acesulfame K is stable both in liquid form and for cooking and has no major health warnings. Some people do complain that it has a bitter taste when used in high concentrations, which is why this sweetener may be combined with other low-calorie sweeteners to improve the taste profile.
Sucralose, approved for use by the FDA in 1998, is a non-caloric sweetener made from sugar. It is 600 times sweeter than sucrose. Its stability enables it to retain sweetness over a wide range of temperatures, which allows it to be used in a variety of foods. It is found as a low-calorie sweetener (Splenda, Nevella) in fruits, juices, baked goods, sauces and syrups. More than 100 studies conducted over 20 years demonstrate the safety of this sweetener. Sucralose is safe for use during pregnancy.
Neotame, approved for use by the FDA in 2002, is the fifth nonnutritive sweetener available in the United States. This sweetener, which is approximately 8000 times sweeter than sucrose, is expected to be used in a wide variety of foods, including beverages, frozen desserts, dairy products, baked goods and chewing gum. Neotame is not yet widely used in products, although there are a few beverages and candies available that contain it.
Stevia. Some people use stevia as a sweetening agent. Stevia is a South American shrub whose leaves have been used for centuries in South American cultures to sweeten a beverage called yerba mate. Stevioside, the main ingredient in stevia, is three hundred times sweeter than sucrose and is calorie-free. Stevia has been available as a dietary supplement and sold in health food stores for a long time, but recently, the FDA approved a highly purified extract of it called rebaudioside A(rebiana). This form of stevia is now available as a tabletop sweetener and will soon be added to beverages and foods.
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