TCS Daily

The Lowdown on Sweet

By Jonathan Robison, PhD, MS - May 18, 2004 12:00 AM

Sugar has definitely gotten a bad rap over the years. It has been blamed for causing (among other things) tooth decay, obesity, diabetes and heart disease. Furthermore, it is common knowledge as reported by parents, teachers and other experts that children become hyperactive after they eat candy and other sugary foods. Indeed, the dangers of sugar have become legendary. Its damaging effects have even been compared to those of another white powder by a well-known consumer advocate group, and an entire industry -- non-sugar sweeteners -- has grown up around the fear produced by the legend. What is it about this wonderful-tasting stuff that inspires such trepidation?

Sugars 101

With carbohydrates and especially sugars being in the news so often recently, it can be confusing to pin down exactly what the terms mean. Sugars are referred to as simple carbohydrates to distinguish them from complex carbohydrates such as starches. The monosaccharides glucose, fructose and galactose combine in pairs called disaccharides to form the most common sugars as shown below:

Food Source
 Sucrose à glucose + fructose (sugar cane, honey, corn syrup)
 Lactose à  glucose + galactose  (milk products)
 Maltose à  glucose + glucose  (malt from grains)

Sugars are further classified as being either naturally occurring -- such as the fructose in fruit or the lactose in milk; or added -- such as the sucrose or other refined sugars that are incorporated into pop and fruit drinks. In examining the relationship between sugars and human health, the most important facts to remember may be that 1) most dietary sugars (and most complex carbohydrates as well) are eventually broken down into the monosaccharide glucose and 2) the body cannot distinguish between sugars that are added to foods and sugars that occur naturally in foods. (1)

Don't Sweat The Sweet Stuff

So what does the research say about the relationship between dietary sugar and human health? Perhaps surprisingly, there is little evidence to support sugar as the dangerous villain that it has been made out to be. Below are some of the most important findings in that regard.

1) Sugar and Heart Disease: The etiology of heart disease is complicated; in fact, there are currently more than 300 identified risk factors. However, diets high in carbohydrates and low in fats provide the cornerstone of dietary recommendations for preventing coronary heart disease. In general, an increase in dietary carbohydrate is associated with a decrease in dietary fats. Research does not support the suggestion that carbohydrates in general or sugars in particular contribute to the etiology of heart disease as the following statements from a variety of prestigious health organizations indicate.

U.S. Food and Agriculture Organization and World Health Organization:

"There is no evidence for a causal role of sucrose in the etiology of coronary heart disease (2)

American Heart Association:

"There are no dietary trials linking sugar consumption and CVD..." (3)

2) Sugar and Obesity. Too many calories from any food will eventually cause weight gain, but per gram, fat is much more likely to do this than sugar. Each gram of fat contributes about 9 calories while each gram of carbohydrate (complex or simple) contributes about 4 to total energy intake. As a recent review of the literature in Family Economics and Nutrition Review concluded,

Many factors contribute to obesity, but evidence does not single out dietary sugar as a cause." (4)

Perhaps surprisingly, a number of population studies actually demonstrate an inverse relationship between sugar consumption and obesity. (5-7) Furthermore, the ability of the body to store carbohydrates is limited and excess intake causes an increase in the amount of carbohydrate burned for energy, whereas excess fat intake does not generally increase fat oxidation. Finally, research indicates that excess fat calories are readily converted to body fat stores while the body only rarely changes excess carbohydrates into fat. (8) Therefore "as fat is stored more efficiently than excess carbohydrate, use of high carbohydrate foods is likely to reduce the risk of obesity in the long term" (2)

3) Sugar and Diabetes. Contrary to much popular wisdom, The American Diabetic Association (ADA) contends that sugar does not cause diabetes, does not make it more difficult to control and can certainly be used as a part of a balanced diet for a person with Diabetes. Clinical studies that have manipulated the amount of sucrose in the diet have generally found no adverse effects of sucrose on average glucose control. (9-11) Therefore, in a recent Position Statement entitled Evidence-Based Nutrition Principles and Recommendations for the Treatment and Prevention of Diabetes and Related Complications, the ADA concluded that: (12)

"Intake of sucrose and sucrose containing foods by people with diabetes does not need to be restricted because of concern about aggravating hyperglycemia."

This is certainly not meant to suggest that individuals with diabetes do not need to be aware of their carbohydrate/sugar intake. Careful monitoring of all carbohydrates and adequate covering with insulin or other glucose-lowering medication when necessary is essential for the ongoing health of these individuals. However, the research consensus to date on the relationship of dietary sugar to diabetes is clearly stated by the World Health Organization:

Sucrose and other sugars have not been directly implicated in the etiology of diabetes." (2)

4) Sugar and Hyperactivity in Children. Perhaps the most pervasive myth surrounding sugar concerns its supposed untoward effects on children. Parents and teachers especially have been convinced that sugary treats result in out of control children. It is not hard to imagine how this myth developed. Parents taking their young children to birthday parties where the kids eat cake and ice cream noticed that they proceeded to get quite rowdy. By association, it was assumed that the food was the culprit. Unfortunately, a more controlled observation might have discovered what was more likely to have been the truth; that the same rowdiness would have occurred even sans sugar. In fact, a recent, in-depth review of the research relating to sugar intake and children's behavior concluded: (13)

"Twelve double-blind, placebo-controlled studies of sugar challenges failed to provide any evidence that sugar ingestion leads to untoward behavior in children with Attention-Deficit Hyperactivity Disorder or in normal children."

Perhaps ironically, the most recent research actually suggests that, far from being a hyperactivity-inducing food, sweets actually appear to play a significant role in helping to calm us down when we are stressed. It turns out that both high sugar and high fat foods are capable of turning off our metabolic responses to chronic stress, decreasing the potential damaging effects of excess stress hormones. (14)

5) Sugar and Dental Caries. All foods containing starches and/or sugars are easily broken down in the mouth to produce acid which in turn increases the risk of dental caries. This risk however, is highly variable among individuals, depending on a host of factors including oral bacteria, saliva, tooth enamel, food substrate, genetic susceptibility, type of food and frequency of consumption. Therefore, although sugar is most certainly involved in tooth decay, research suggests that "good oral hygiene, good genes, fluoridation of water and restricting snacks between meals can prevent tooth decay, no matter how high the sugar consumption." (4)

Sweetening The Pot

Like so many other food-related issues, what is missing in relation to sugar is largely a matter of balance. There is little evidence that sugar is a dangerous food that needs to be treated as if it were a controlled substance. While high intakes can certainly affect oral health and displace other important nutrients in the diet, the same can be said of almost any food eaten in excess. Sugar is a good source of quick energy for our bodies and for our brains as well.

Perhaps even more importantly, sugar adds sweetness and taste to our foods. This enables us to enjoy a wider variety of foods and helps to make those foods more palatable. Most people would consider strawberries to be a very healthy food. Yet strawberries, particularly in the off-season, may not be sweet enough to attract the attention of some people, particularly young children. However, a quick dipping in sugar permits the full sweetness of the nutritious fruit to come forth and allows us to get the benefits of its vitamin C and other nutrients. The world can be a bitter place sometimes. Perhaps this is why sweets are one of the few innate food preferences that we have as human beings.


1. Murphy S, Johnson R. The scientific basis of recent US guidance on sugars intake. The American Journal of Clinical Nutrition 2003;78(4):827S-833S.

2. Food and Agriculture Organization of the United States and the World Health Organization. Carbohydrates in Human Nutrition. 1998; (FAO Food and Nutrition Paper - 66) Chapter 3, Dietary Carbohydrate and disease.

3. Howard B, Wylie-Rosett J. Sugar and Cardiovascular Disease: A Statement for Healthcare Professionals From The Committee on Nutrition of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association. Circulation 2002;106:523-527.

4. Mardis, A. Current knowledge of the health effects of sugar. Family Economics and Nutrition Review; Washington; 2001;13(1):87-91.

5. Gibney, M., Siman-Grant, M., Stanton, J., Keast, D. Consumption of Sugars. American Journal of Clinical Nutrition 62(1 suppl):178S-193S.

6. Gibson, S., Williams, S. Dental caries in pre-school children: Associations with Social Class, tooth brushing habit and consumption of sugars and sugar-containing food. Further analysis of data from the National Diet and Nutrition Survey of children aged 1.5-4.5 years. Caries Research 33(2):101-113.

7. Ruxton, C., Garceau, F., Cottrell R. Guidelines for Sugar Consumption in Europe: Is a quantitative approach justified? European Journal of Clinical Nutrition 1999;53(7):503-513.

8. Food and Agriculture Organization of the United States and the World Health Organization. Carbohydrates in Human Nutrition. 1998; (FAO Food and Nutrition Paper - 66) Chapter 2, The Role of Carbohydrates in Maintenance of Health.

9. Bantle, J., Swanson, J., Thomas, W., et al. Metabolic effects of dietary fructose and sucrose in types I and II diabetic subjects. Diabetes Care 1993;16:1301-1305.

10. Bantle, J., Swanson, J., Thomas, W., etal. Metabolic effects of dietary fructose and sucrose in types I and II diabetic subjects. JAMA 1986;256:3241-3246.

11. Wise, J., Kleim, K., Huisinga, J., et al. Effect of sucrose-containing snacks on blood glucose control. Diabetes Care 1989;12:423-426.

12. American Diabetes Association Position Statement. Evidence-Based Nutrition Principles and Recommendations for the Treatment and Prevention of Diabetes and Related Complications. Diabetes Care 2002;25(1):202-212.

13. Krummel, D., Seligson F., Guthrie, H. Hyperacticity: Is candy causal? Critical Review of Food Science and Nutrition 1996;36(1-2):31-47

14. Dallman, M. Pecoraro, N., Akana, S., et. al. Chronic Stress and Obesity: A New View of "Comfort Food." Proceedings of the National Academy of Sciences 2003;100(20):11696-11701.


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