Ask someone to name his or her favorite food and, chances are, you’ll get a sweet answer such as cookies, cake, candy, or ice cream. However, sugars have long stirred up concern because of their possible link to health conditions such as obesity, diabetes, and heart disease.

Sugars are present throughout our lives, beginning with the “sweet” amniotic fluid in the womb, moving on to the milk sugar lactose in breast milk or formula, and then on to favorite foods. Sugars provide an array of functional properties important to food processing, as well as energy (calories), and sensory pleasure.

The question becomes, what does consuming sugar mean for our health?

A scientific session at the 2002 American Dietetic Association annual meeting, jointly sponsored by the International Food Information Council (IFIC) and the International Life Sciences Institute (ILSI), addressed this question. A panel of experts presented the latest consensus science regarding the impact of sugars on health, and offered guidelines for effectively communicating with consumers about this often-confusing topic. This article summarizes significant points from the session.

Challenges to Interpreting the Science

Several challenges complicate the interpretation of the science surrounding sugars and health. For instance, various definitions are commonly used to describe the sugars in foods and beverages. See the chart below.

Accurate assessment of sugars-consumption patterns is difficult because different methods are used to collect and report data. Food supply (disappearance) data collected by the U.S. Department of Agriculture’s (USDA’s) Economic Research Service (ERS) estimates consumption by tracking changes in food availability or supply by measuring the flow of commodities through the U.S. marketing system. In 2000, the food supply provided 32 teaspoons of caloric sweeteners per person per day, up 23 percent since the 1980-1984 survey. A concern is that food supply data overstate the consumption of caloric sweeteners because the data include food that is disposed of, not finished, inedible, or lost through spoilage or waste. However, the ERS makes some adjustments to the data to account for these factors.

Self-reported data derived from the USDA Continuing Survey of Food Intakes of Individuals (CSFII) indicate that during the 1994-1996 survey period, mean intakes of added sugars were 20.5 teaspoons per day for people older than 2 years of age, up 31 percent from the 1989-1991 survey period. CSFII defines “added sugars” as sugars eaten separately or used as ingredients in processed or prepared foods, such as white sugar or corn syrup.

Recommendations for sugars intake also are a mixed bag. The 2000 Dietary Guidelines for Americans say, “Choose beverages and foods to moderate your intake of sugars.” Although the Institute of Medicine’s (IOM’s) 2002 report Dietary Reference Intakes for Macronutrients did not set a Tolerable Upper Intake Level for sugars, it suggests a maximum intake of 25 percent of calories from added sugars. According to the IOM report, higher intakes are associated with a dramatic decrease in micronutrient intakes, especially calcium. The IOM panel determined no other adverse effects.

Sugars and Health: What the Latest Science Says

Despite the continuous controversy that swirls around sugars’ impact on health, scientific consensus indicates that no adverse health effects can be directly attributed to sugars consumption, other than an association with dental carries. The following sections highlight the science in several key areas.

Obesity: Obesity results when more calories are eaten than expended, whatever the source of the extra calories. Although there is no direct connection between added sugars and obesity, health guidelines to prevent or reduce obesity generally recommend increasing physical activity and reducing extra calories by eating fewer fats and sugars.

Diabetes and Insulin Sensitivity: The sugars in foods do not increase blood glucose levels any higher or faster than starches do. Therefore, current American Diabetes Association nutritional recommendations do not provide specific guidelines for sugars intake, except that sugars should be substituted on a calorie-for-calorie basis with other carbohydrates. Debate continues regarding the merit of using the glycemic index of starches and sugars in nutritional planning for people with diabetes.

Animal research shows that diets high in sucrose and fructose decrease insulin sensitivity. However, the results of experimental studies with humans are conflicting, with limited evidence showing that insulin sensitivity decreases when sugars intake is high (greater than 30 percent of daily calories for sucrose or greater than 15 percent of daily calories for fructose). Epidemiological studies do not show a link between sucrose consumption and insulin sensitivity independent of other dietary factors. More research is needed to determine the effect of sugars on insulin sensitivity in humans.

Serum Triglycerides and Heart Disease: Short-term studies show that sugars produce a dose-dependent increase in serum triglyceride levels. However, diets that meet recommendations for fiber, saturated fat, and unsaturated fat lessen this effect. Triglyceride levels are more likely to increase in obese individuals with metabolic syndrome who consume a high-sugar diet. However, several studies indicate that modest weight loss coupled with a shift to a diet rich in fruits, vegetables, and whole grains prevents a rise in triglyceride levels even when diets are high in sugars (greater than 20 percent of calories). Carefully controlled clinical studies are needed to determine whether an increase in triglyceride levels resulting from diets high in sugars affects the risk for heart disease.

Dental Caries: Sugars and cooked starches (i.e., bread, pasta, crackers, and chips) are fermentable carbohydrates that contribute to the risk for caries. The degree of risk from a carbohydrate-rich food is related to several factors such as form, stickiness, exposure time, and frequency of consumption. However, risk is decreased by several factors, with the most important being the use of topical fluorides and fluoridated water. Also important are good oral hygiene and eating a balanced diet in line with current dietary guidelines.

The Bottom Line: Research into potential links between sugars and health continues in several areas. Meanwhile, experts agree that a health risk is not posed by enjoying sweet foods and beverages in moderation as part of a balanced diet and a physically active lifestyle.