Health Effects of Sugars and Alternative Sweeteners

Fiber-rich carbohydrate foods such as vegetables, whole grains, legumes, and fruits should predominate in people’s diets; the naturally occurring sugars in these foods and in milk are acceptable because they are accompanied by many nutrients. In contrast, concentrated sweets such as candy, cola beverages, and other soft drinks, cookies, pies, cakes, and other foods with added sugars add kcalories, but few, if any, other nutrients or fiber. The Dietary Guidelines for Americans offer clear advice on added sugars: reduce intake. People who want to limit their use of sugar may choose from two sets of alternative sweeteners: sugar alcohols and nonnutritive sweeteners.

Sugars

Recent decades have seen a dramatic upward trend in the consumption of added sugars. Sugary foods and beverages taste delicious, cost little money, and are constantly available, making overconsumption extremely likely. Though people are adding less sugar in the kitchen, food manufacturers are adding plenty to foods during processing. Soft drinks and other sugar-sweetened beverages are a major source of added sugars in the diets of U.S. consumers. An estimated 75 percent of the packaged foods in the United States contain sweeteners, mostly added sugars. On average, U.S. adults consume almost 15 percent of their daily energy intake from added sugars. Most people can afford only a little added sugar in their diets if they are to meet nutrient needs within calorie limits.

The U.S. population is not alone in increasing sugar consumption. The trend is a worldwide phenomenon. In response, the World Health Organization has also taken a stand on sugar intake: consume less than 10 percent of total calories from added sugars. The World Health Organization further suggests that consuming less than 5 percent will provide additional health benefits.

The increase in sugar consumption has raised many questions about sugar’s effects on health. In moderate amounts, sugars add pleasure to meals without harming health. In excess, however, sugars can be detrimental, and the average American diet currently delivers excessive amounts. Mounting evidence links high intakes of added sugars with obesity and other chronic diseases. Sugars can also contribute to nutrient deficiencies by supplying energy (calories) without providing nutrients and to tooth decay, or dental caries.

Sugar and Obesity

Over the past several decades, as obesity rates increased sharply, consumption of added sugars reached an all-time high—largely because high-fructose corn syrup use, especially in beverages, surged. High-fructose corn syrup is composed of fructose and glucose in a ratio of about 50:50. Compared with sucrose, high-fructose corn syrup is less expensive, easier to use, and more stable. In addition to being used in beverages, high-fructose corn syrup sweetens candies, baked goods, and hundreds of other foods.

The use of high-fructose corn syrup sweetener parallels unprecedented increases in the incidence of obesity, but does this mean that the increasing sugar in- takes are responsible for the increase in body fat and its associated health problems?

Excess sugar in the diet may be associated with more fat on the body. When they are eaten in excess of need, energy from added sugars contributes to body fat stores, raising the risk of weight gain. When total energy intake is controlled, however, moderate amounts of sugar do not cause obesity. Thus, to the extent that sugar contributes to an excessive energy intake, it can play a role in the development of obesity.

Because swallowing liquids requires little effort, the liquid form of sugar in soft drinks makes it especially easy to overconsume calories. Sugar-sweetened beverages are energy-dense, providing more than 150 calories per 12-ounce can, and many people drink several cans a day. The sugar calories of sweet beverages also cost less than many other energy sources, and they are widely available. The convenience, economy, availability, and flavors of sugary foods and beverages encourage overconsumption.

Limiting selections of foods and beverages high in added sugars can be an effective weight-loss strategy, especially for people whose excess calories come primarily from added sugars. Replacing a can of cola with a glass of water every day, for example, can help a person lose a pound (or at least not gain a pound) in one month. That may not sound like much, but it adds up to more than 10 pounds a year, for very little effort.

Sugar and Heart Disease

Added sugars also influence the balance between the body’s fat-making and fat-clearing mechanisms, a balance that plays critical role in the development of heart disease.16 Fructose stimulates the body’s fat-making pathways and impairs its fat-clearing pathways in ways that could lead to an unhealthy build-up of blood lipids.

To determine whether added sugars raise blood lipids, researchers studied more than 6000 healthy adults. They observed that people with higher intakes of added sugars had blood lipid values indicating an increased risk of heart disease.

In another study, young adults who consumed more sugar-sweetened beverages had greater abdominal fatness, more harmful blood lipids, and higher blood pressure than those who drank fewer.19 It may not take an unrealistic amount of added sugars to cause this effect. As little as the equivalent of one or two fructose- or sucrose-sweetened soft drinks a day consumed for only a few weeks significantly changes blood lipids in ways that may pose risks to the heart and arteries.

Sugar and Nutrient Deficiencies

Empty-calorie foods that contain lots of added sugars such as cakes, candies, and sodas provide the body with glucose and energy, but few, if any, other nutrients. By comparison, foods such as whole grains, vegetables, legumes, and fruits that contain some natural sugars and lots of starches and fibers also provide protein, vitamins, and minerals.

A person spending 200 kcalories of a day’s energy allowance on a 16-ounce soda gets little value for those kcalories. In contrast, a person using 200 kcalories on three slices of whole-wheat bread gets 9 grams of protein, 6 grams of fiber, plus several of the B vitamins with those kcalories. For the person who wants something sweet, a reasonable compromise might be two slices of bread with a teaspoon of jam on each. The amount of sugar a person can afford to eat depends on how many discretionary calories are available beyond those needed to deliver indispensable vitamins and minerals.

By following the USDA Food Patterns and making careful food selections, a typical adult can obtain all the needed nutrients within an allowance of about 1500 kcalories. Some people have more generous energy allowances. For example, an active teenage boy may need as many as 3000 calories a day.

If he eats mostly nutritious foods, then he may have discretionary calories available for cola beverages and other “extras.” In contrast, an inactive older woman who is limited to fewer than 1500 calories a day can afford to eat only the most nutrient-dense foods—with few, or no, discretionary calories available.

Added sugars contribute to nutrient deficiencies by displacing nutrients. For nutrition’s sake, the appropriate attitude to take is not that sugar is “bad” and must be avoided, but that nutritious foods must come first. If nutritious foods crowd sugar out of the diet, that is fine—but not the other way around. As always, balance, variety, and moderation guide healthy food choices.

Sugar and Dental Caries

Does sugar contribute to dental caries? The evidence says yes. Any carbohydrate-containing food, including bread, bananas, or milk, as well as sugar, can support bacterial growth in the mouth. These bacteria produce the acid that eats away tooth enamel. Of major importance is the length of time the food stays in the mouth. This, in turn, depends on the composition of the food, how sticky the food is, how often a person eats the food, and especially whether the teeth are brushed afterward.

Total sugar intake still plays a major role in caries incidence; populations whose diets provide no more than 10 percent of calories from sugar have a low prevalence of dental caries. The Academy of Nutrition and Dietetics and the Dietary Guidelines for Americans recommend a combined approach to prevent dental caries— practicing good oral hygiene, drinking fluoridated water, and reducing the amount of time sugars and starches are in the mouth. 

Recommended Sugar Intakes

Moderate sugar intakes are not harmful and make eating more enjoyable, but the average U.S. intake is well above moderate. Thus, the Dietary Guidelines for Americans urge people to “reduce the intake of calories from added sugars.” These added sugar calories (and those from solid fats and alcohol) are considered discretionary calories—and most people need to limit their intake. The USDA Food Patterns suggest about 8 teaspoons of sugar, about the amount in one 12-ounce soft drink, in a nutrient-dense 2000-kcalorie eating pattern.

The USDA Food Patterns recommendations for sugar represent about 5 to 10 percent of the day’s total energy intake. As noted earlier, the World Health Organization agrees that people should restrict their consumption of added sugars to less than 10 percent of total energy and that reducing added sugar intake to less than 5 percent of total energy would have additional health benefits.

The DRI committee did not set a Tolerable Upper Intake Level for added sugars, but, as mentioned, excessive intakes can interfere with sound nutrition and good health. Few people can eat lots of sugary treats and still meet all of their nutrient needs without exceeding their calorie allowance. Instead, the DRI committee suggests that added sugars should account for no more than 25 percent of the day’s total energy intake.

One out of eight in the U.S. population exceeds this rather high maximum intake. For a person consuming 2000 calories a day, 25 percent represents 500 kcalories from added sugars—the equivalent of 40 ounces of cola, 1⁄2 cup of honey, 125 jelly beans, 23 marshmallows, or 30 teaspoons of sugar. Perhaps an athlete in training whose energy needs are high can afford the added sugars from sports drinks without compromising nutrient intake, but most people would do better following recommendations to limit added sugar consumption to less than 10 percent of the day’s total energy intake.

Recognizing Sugars

People often fail to recognize sugar in all its forms and so do not realize how much they consume. To help your clients estimate their sugar intakes, tell them to treat all of the following concentrated sweets as equivalent to 1 teaspoon of white sugar (4 grams of carbohydrate):

  • 1 teaspoon brown sugar, candy, jam, jelly, any corn sweetener, syrup, honey, molasses, or maple sugar or syrup
  • 1 tablespoon ketchup
  • 11⁄2 ounces carbonated soft drink

These portions of sugar all provide about the same number of calories. Some are closer to 10 kcalories (for example, 14 calories for molasses), whereas some are more than 20 kcalories (22 kcalories for honey), so an average figure of 16 calories is an acceptable approximation. 

People often ask: What is the difference between honey and white sugar? Is honey, by virtue of being natural, more nutritious? Honey, like white sugar, contains glucose and fructose. The difference is that, in white sugar, the glucose and fructose are bonded together in pairs, whereas in honey some of them are paired and some are free single sugars. When you eat either white sugar or honey, though, your body breaks all of the sugars apart into single sugars. It ultimately makes no difference, then, whether you eat single sugars linked together, as in white sugar, or the same sugars unlinked, as in honey; they will end up as single sugars in your body.

Honey does contain a few vitamins and minerals, but not many. Honey is denser than crystalline sugar, too, so it provides more energy per spoonful. Honey and white sugar are similar nutritionally—and both fall short of milk, legumes, fruits, grains, and vegetables. Honey may offer some health benefits, however: It seems to relieve nighttime coughing in children and reduce the severity of mouth ulcers in cancer patients undergoing chemotherapy or radiation.

Some sugar sources are more nutritious than others, though. Consider a fruit such as an orange. The orange provides the same sugars and about the same energy as a tablespoon of sugar or honey, but the packaging makes a big difference in nutrient density. The sugars of the orange are diluted in a large volume of fluid that contains valuable vitamins and minerals, and the flesh and skin of the orange are supported by fibers that also offer health benefits. A tablespoon of honey offers no such bonuses. Of course, a cola beverage, containing many teaspoons of sugar, offers no advantages either.

Alternative Sweeteners: Sugar Alcohols

The sugar alcohols are carbohydrates, but they trigger a lower glycemic response and yield slightly less energy (2 to 3 calories per gram) than sucrose (4 calories per gram) because they are not absorbed completely.24 The sugar alcohols are sometimes called nutritive sweeteners because they do yield some energy. One exception, erythritol, cannot be metabolized by human enzymes and so is calorie-free.

Sugar alcohols occur naturally in fruits and vegetables; they are also used by manufacturers to provide sweetness and bulk to cookies, sugarless gum, hard candies, and jams and jellies. Unlike sucrose, sugar alcohols are fermented in the large intestine by intestinal bacteria. Consequently, side effects such as gas, abdominal discomfort, and diarrhea make sugar alcohols less attractive than nonnutritive sweeteners.

The advantage of using sugar alcohols is that they do not contribute to dental caries. Bacteria in the mouth metabolize sugar alcohols much more slowly than sucrose, thereby inhibiting the production of acids that promote caries formation. They are therefore valuable in chewing gums, breath mints, and other products that people keep in their mouths awhile.

The Food and Drug Administration (FDA) allows food labels to carry a health claim about the relationship between sugar alcohols and the nonpromotion of dental caries as long as certain FDA criteria, including those for sugar-free status, are met. 

Alternative Sweeteners: Nonnutritive Sweeteners

The non-nutritive sweeteners sweeten with minimal or no carbohydrate or energy. The human taste buds perceive many of them as extremely sweet, so just tiny amounts are added to foods to achieve the desired sweet taste.25 The FDA endorses nonnutritive sweeteners as safe for use over a lifetime within Acceptable Daily Intake (ADI) levels. Like sugar alcohols, nonnutritive sweeteners make foods taste sweet without promoting tooth decay. 

Nonnutritive Sweeteners and Weight Management

Whether the use of non-nutritive sweeteners promotes weight loss or improves health by reducing total kcalorie intakes is not known with certainty. Some research even suggests that their use may promote weight gain through unknown mechanisms; these are topics of current research. When people reduce their energy intake by replacing sugar in their diets with non-nutritive sweeteners and then compensate for the reduced energy at later meals, energy intake may stay the same or increase. Using nonnutritive sweeteners will not automatically lower energy intake; to successfully control energy intake, a person needs to make informed diet and activity decisions throughout the day.

Safety of Nonnutritive Sweeteners

Through the years, questions have emerged about the safety of nonnutritive sweeteners, but these issues have since been resolved. For example, early research indicating that large quantities of saccharin caused bladder tumors in laboratory animals was later shown to be inapplicable to humans.

Common sense dictates that consuming large amounts of saccharin is probably not safe, but consuming moderate amounts poses no known hazard. Aspartame, a sweetener made from two amino acids (phenylalanine and aspartic acid) is one of the most thoroughly studied food additives ever approved, and no scientific evidence supports the Internet stories that accuse it of causing disease.

However, aspartame’s phenylalanine base poses a threat to those with the inherited disease phenylketonuria (PKU). People with PKU cannot dispose of phenylalanine efficiently. Food labels warn people with PKU of the presence of phenylalanine in aspartame-sweetened foods. In addition, foods and drinks containing nonnutritive sweeteners have no place in the diets of even healthy infants or toddlers.

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