September 2012 Issue

Sweeteners: Facts and Fallacies — Learn the Truth About the Different Types of Sweeteners to Better Counsel Patients
By Connie Diekman, MEd, RD, LD, FAND
Today’s Dietitian
Vol. 14 No. 9 P. 42

Our love of something sweet isn’t totally the result of all the options available in the supermarket; it’s part of our biology. Sweetness is one of the five basic tastes and is often studied in breast-fed infants, who have clearly shown a biological response to the sweetness of breast milk with a broad smile.

The sweet receptors found on the tongue have been extensively studied and are thought to play a role in stimulating appetite. However, researchers have done less study of sweet receptors found in the gastrointestinal tract, pancreatic cells, the lungs, and the biliary tract. Views on how these cells impact our desire for sweetness continues to evolve, but it’s clear that without sweet taste in the mouth, the sweet receptors in the gastrointestinal tract do not convey taste.1

While the love of sweetness is a basic biological taste, sugar has been in the news during the past several years because of the growing problem of overweight and obesity. As the consumption of foods with added sugar has increased, so has the hypothesis that added sugars are linked to the overweight and obesity problem.

The 2010 Dietary Guidelines provide good evidence related to our intake of added sugars, indicating that 16% of total energy intake is from added sugar. This figure reflects National Health and Nutrition Examination Survey (NHANES) data from 2005 and 2006, while more recent NHANES data show an estimate of 14.6% of total energy intake. According to 2005-2006 NHANES data, sugar-sweetened beverages (eg, soft drinks, energy drinks, sports drinks, sugar-sweetened water), grain-based desserts, and fruit drinks are the top sources of added sugar calories for all age groups, contributing close to 60% of the added sugar intake.2

This evidence helps illustrate which foods contribute added sugar to the average diet while also showing how calories from added sugars are exceeding recommended amounts. Based on previously mentioned studies, it’s estimated that adults older than the age of 19 consume an average of 20 tsp of added sugars each day, exceeding the recommended intake of 8 tsp per day.3

The food industry has worked to develop lower-calorie but just-as-sweet options by incorporating nonnutritive sweeteners into many products. The expanding use of nonnutritive sweeteners has brought questions about the role of these substances in weight management, whether it’s safe to regularly consume them, and whether natural forms of sugar are safer. There’s not yet a consensus, but many studies are investigating these questions.

Types of Sweeteners
Nutritive sweeteners, which are also often referred to as sugar, added sugar, or caloric sweeteners, contain carbohydrates that are a source of energy. In addition to taste, sugar performs other functions in foods, ranging from adding texture to baked goods to preventing bacterial growth in jams and jellies. Added sugars provide little nutritional value beyond the calories they contain but do not pose a health or safety risk unless used in excess or at the expense of other nutrient-dense foods.4

Nonnutritive sweeteners, also referred to as low-calorie, artificial, or intense sweeteners, provide little to no energy when consumed. Nonnutritive sweeteners are many times sweeter than sugar, so they are used in significantly smaller amounts, resulting in little energy intake. They lack some of the functionality of added sugars, which does limit their usage.

In addition to providing a calorie-free option, compared with sugar, nonnutritive sweeteners generally do not increase blood sugar levels, making them a good option for people with diabetes. Also, since nonnutritive sweeteners do not contain carbohydrates, they do not promote tooth decay.

Nutritive Sweeteners
Nutritive sweeteners can be divided into two groups: naturally occurring sugars, such as those found in fruits, vegetables, and dairy foods, and added sugars.

Added sugars are defined by the USDA as caloric sweeteners added to foods during processing, preparation, or before consumption.2 Sucrose, probably the most recognizable added sugar, is made from sugar cane or sugar beets and is the white table sugar most consumers know. Brown sugar, confectioner’s sugar, turbinado sugar, and unrefined sugar made from sugar cane juice are also sucrose.2,4 Other added sugars include agave nectar, corn syrup or corn syrup solids, dextrose, fructose, high-fructose corn syrup, honey, inverted sugar, maple syrup, and molasses.

Agave nectar, honey, molasses, and turbinado sugar often are viewed as more natural choices because they’re derived from plant sources, so they may be perceived to be more healthful options than sucrose. The evidence doesn’t support that perception. The metabolism of all sugars follows a similar pathway, with the core molecule glucose being the end result of digestion. Avoiding added sugars requires good label reading and recognizing words that indicate the presence of sugar in a product.

Nonnutritive Sweeteners
The first nonnutritive sweetener, saccharin, was discovered in 1879. Since then, four other nonnutritive sweeteners, along with the herb extract stevia and the fruit extract luo han guo, have joined the category. The seven nonnutritive sweeteners currently approved for use in the United States are acesulfame-K, aspartame, luo han guo (monk fruit) extract, neotame, saccharin, stevia, and sucralose.3

Acesulfame-K (Sweet One, Sunett) is a combination of an organic acid and potassium and is 200 times sweeter than sucrose. It was originally approved in 1988 for use in food products and as a tabletop sweetener, with approval for use in beverages 10 years later. General-purpose sweetener usage was approved in 2003.3,5

Aspartame (Equal, NutraSweet) is a combination of the amino acids phenylalanine and aspartic acid and is 160 to 220 times sweeter than sucrose.3 Because it contains phenylalanine, foods with aspartame must carry a statement warning those with the rare disorder phenylketonuria about the presence of aspartame in the product. The FDA first approved its usage in 1981, with beverage use approval coming two years later. Finally, it was approved as a general-usage sweetener in 1996.3,5

Luo han guo is the extract of the swingle fruit and is often referred to as monk fruit extract. It’s between 150 and 300 times sweeter than sucrose.3 The wide range of sweetness is a function of the type of glycoside that exists in the fruit extract. It received FDA approval in 2009.6

Neotame also is a combination of the amino acids phenylalanine and aspartic acid, but it’s between 7,000 and 13,000 times sweeter than sucrose.3 This high intensity of sweetness means that it contains very little phenylalanine, therefore it doesn’t require a warning label like aspartame.5 It was approved by the FDA in 2002 as a general-use sweetener but is used in very few foods.3,5

Saccharin (SweetN’ Low), which is often combined with other sweeteners, is a soluble sodium salt not metabolized by the body, so it’s eliminated without yielding any calories. Saccharin is 300 times sweeter than sugar. Its safety was challenged in 1977 because of studies showing it caused tumors in rats.3 At the time, it was the only artificial sweetener on the market, and Congress subsequently permitted its continued availability during further testing to ensure that those with diabetes would have a sugar alternative. Subsequent studies have shown no link between saccharin and cancer in humans. Saccharin often is combined with other nonnutritive sweeteners to improve the flavor palate or increase the versatility of the sweeteners.

Stevia (Truvia) is extracted from the leaves of the Stevia rebaudiana Bertoni plant, which is native to South America.5 Stevia leaves are sold as dietary supplements, but they aren’t the same as steviol glycoside, which is the source of the sweet taste in stevia. Stevia is 200 to 300 times sweeter than sugar, is more stable in liquid form than aspartame or acesulfame-K, and is found in many foods and beverages and as a tabletop sweetener. It was approved for use in 2008.3,5

Sucralose (Splenda), which is 600 times sweeter than sugar, starts as a regular sugar molecule, then the three hydroxyl groups are removed and three chlorine molecules take their place. This new molecule can’t be absorbed by the body and is excreted unchanged from the body. Sucralose was approved in 1998 for use in 15 foods and beverages and then received approval as a general-purpose sweetener in 1999. What’s more, sucralose is heat stable.3,5

Sugar Alcohols
Another category of sweetener is sugar alcohols, or polyols. They contain calories but because of their digestibility and metabolism, the calorie yield per sugar alcohol varies. Most sugar alcohols are used in combination with another sugar alcohol or with nonnutritive sweeteners to help reduce the actual calorie level of foods that contain sugar alcohols. A recent Academy of Nutrition and Dietetics (the Academy) position paper, “Use of Nutritive and Nonnutritive Sweeteners,” provides a good review of the sugar alcohols currently in use, which include sorbitol, mannitol, xylitol, and erythritol.3

Safety
Safety concerns have been raised about nonnutritive sweeteners. In the United States, the FDA is charged with approving food additives such as nonnutritive sweeteners before they can be made available for sale.7 As the FDA reviews products containing nonnutritive sweeteners, they establish an acceptable daily intake (ADI), based on body weight, that is deemed safe over a lifetime. The ADI is set at 1% of the amount that has been found not to produce any adverse health effects in animal studies.3,5

Here is a brief summary of how the various nonnutritive sweeteners have fared as far as testing:

• Acesulfame-K has been thoroughly tested in animal studies using amounts that significantly exceed those anyone could consume, and there has been no evidence of tumors or cancer.5,7

• Aspartame has been tested extensively due to its long history and questions related to tumor development. Aspartame’s 1981 FDA approval followed extensive testing, which showed no evidence of cancer. But in 1996, a report raised questions about its connection to brain tumors. Once again, extensive review of National Cancer Institute (NCI) data showed that the overall incidence of brain tumors started to increase in 1973, before aspartame was available for consumption, and continued until 1985. This data, along with evidence that shows brain cancer incidence is higher in those over the age of 70, led the NCI to declare that there was no link between aspartame and brain tumor development.7

• Luo han guo received Generally Recognized as Safe status from the FDA in 2009.6

• Neotame was approved for use in 2002 after the FDA reviewed more than 100 studies showing no evidence of health risks or a connection to cancer.

• Saccharin’s safety has been discussed and reviewed for much of the 40-plus years it has been in use. In 1977, the FDA issued a warning related to bladder cancer in rats, but subsequent research demonstrated that the mechanism in rats was not relevant to humans. As a result of these findings, starting in 2001, products containing saccharin no longer need to carry the warning label.5,6

• Stevia has been documented as safe for use since the 1980s, and a 2008 review by the Joint Expert Committee on Food Additives concluded it’s safe for general use.5

• Sucralose was deemed safe based on extensive toxicology studies, though human research is limited.3

The Academy’s Evidence Analysis Library (EAL) project on nutritive and nonnutritive sweeteners assesses the body of evidence related to adverse effects of nonnutritive sweeteners, but the articles used in the library are only human subject research. The EAL asks the following question: What’s the evidence from human subjects research that (the individual sweetener) consumption is associated with adverse effects in the general population? While the EAL gives aspartame’s role in energy-restricted diets a grade of 1, or good, the grade for other nonnutritive sweeteners is limited due to the low number of human studies.8

Trends data on consumption of sugar-sweetened beverages and foods show a 41% increase from 1989 to 2004. During the same time period, the intake of nonnutritive sweeteners increased 34% from 493 g to 663 g per consumer.9 A 2006 review on intake levels of nonnutritive sweeteners assessed intake relative to safety and found that intake of acesulfame-K, aspartame, and saccharin fell below the ADI for each. Data were lacking on newer nonnutritive sweeteners, with the review reporting little change in nonnutritive sweetener intake from 1999 to publication of the review.10

Role in Weight Management
The use of nonnutritive sweeteners in weight management is a point of much discussion and research. The 2010 Dietary Guidelines recommend that “replacing added sugars with non-caloric sweeteners may reduce calorie intake in the short-term, yet questions remain about their effectiveness as a weight management strategy.”2

A multitude of studies have attempted to assess whether nonnutritive sweeteners can suppress appetite as a means of lowering food intake, with little positive outcome, but some have demonstrated that using beverages with nonnutritive sweeteners in place of sugar-sweetened beverages can meet the desire for sweet taste while reducing calorie intake. If such changes are implemented within an overall calorie-controlled eating plan, the nonnutritive sweeteners can aid weight loss or maintenance. But most studies associated with nonnutritive sweeteners and weight control have been observational studies, and a recent article calls for more controlled studies to assess the role of nonnutritive sweeteners in weight management.11

Final Thoughts
While the science behind nonnutritive sweeteners is an important part of how RDs prepare themselves to help their clients, understanding how they function and how their tastes vary can help dietitians guide patients to an appropriate choice.

“Nonnutritive sweeteners all trigger slightly different taste receptors, and they have different properties when used for different applications (heated or in acid foods),” says Cindy Fitch, PhD, RD, a coauthor of the Academy’s position paper on sweeteners. “People who want to use a nonnutritive sweetener should try a few of them, alone or in combination, to find the taste that they prefer.”

— Connie Diekman, MEd, RD, LD, FAND, is director of university nutrition at Washington University in St Louis.

 

References
1. Brown RJ, Rother KI. Non-nutritive sweeteners and their role in the gastrointestinal tract. J Clin Endocrinol Metab. 2012;Epub ahead of print.

2. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th ed. Washington, DC: US Government Printing Office; 2010.

3. Fitch C, Keim KS. Position of the Academy of Nutrition and Dietetics: use of nutritive and nonnutritive sweeteners. J Acad Nutr Diet. 2012;112(5):739-758.

4. Sweeteners — sugars. MedlinePlus website. http://www.nlm/nih.gov/medlineplus/ency/article/002444.htm. Updated May 5, 2011. Accessed June 18, 2012.

5. Facts about low-calorie sweeteners. International Food Information Council Foundation website.
http://www.foodinsight.org/Content/6/LCS Fact Sheet_11-09.pdf. November 2009. Accessed June 19, 2012.

6. Agency response letter GRAS notice no. GRN 000301. US Food and Drug Administration website. http://www.fda.gov/Food/FoodIngredientsPackaging/GenerallyRecognizedasSafeGRAS/
GRASListings/ucm200326.htm
. January 15, 2010. Accessed June 21, 2012.

7. Artificial sweeteners and cancer. National Cancer Institute website. http://www.cancer.gov/cancertopics/factsheet/Risk/artificial-sweeteners. Reviewed August 5, 2009. Accessed June 21, 2012.

8. Nutritive and nonnutritive sweeteners. Academy of Nutrition and Dietetics Evidence Analysis Library. http://www.adaevidencelibrary.com/topic.cfm?cat=4116. Accessed June 25, 2012.

9. Mattes RD, Popkin BM. Nonnutritive sweetener consumption in humans: effects on appetite and food intake and their putative mechanisms. Am J Clin Nutr. 2009;89(1):1-14.

10. Renwick AG. The intake of intense sweeteners — an update review. Food Addit Contam. 2006;23(4):327-338.

11. Anderson GH, Foreyt J, Sigman-Grant M, Allison DB. The use of low-calorie sweeteners by adults: impact on weight management. J Nutr. 2012;142(6):1163S-1169S.

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