Sugars and Health

Behaviour

Although many believe that sugar can lead to hyperactivity and other behavioural problems in children and adults, scientific evidence suggests otherwise.

• Hyperactivity
• Memory
• Mood
• Addiction
• References

Hyperactivity

Several comprehensive scientific reviews have concluded that no evidence exists to link sugar intake to hyperactivity in normal children or those with Attention Deficit Hyperactivity Disorder (ADHD). Most recently, both the 2002 joint US/Canada Dietary Reference Intakes report on macronutrients, and a report on “Carbohydrates in Human Nutrition” by the Food and Agriculture Organization (FAO)/World Health Organization (WHO), concluded that sugars do not affect behaviour or cognitive performance in children.

The FAO/WHO report concluded that “it is not appropriate to recommend restricting a child’s sugar intake for the purpose of trying to control behaviour.” Rather, they recommend that ADHD, or true hyperactivity, which is a complex disorder found in only 2-5% of school-aged children, be diagnosed and treated using established medical interventions.

Despite this evidence, many people still believe that sugar causes hyperactivity in children. This belief can be partly explained by the fact that many people mistakenly attribute the excitement surrounding events such as birthday parties and Halloween to sugar, rather than to the event itself.

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Memory

Acute

Glucose is an important nutrient for the brain. Researchers have demonstrated that brain glucose utilization increases during cognitive functioning and that increases in blood glucose levels can improve memory.

Numerous animal and human studies have shown that a glucose-containing drink improves cognitive performance as early as 15 minutes, and up to one hour, after ingestion compared to a calorie-free sweetened placebo drink. The effects are especially evident in people with pre-existing memory deficits including the healthy elderly and patients with Alzheimer Disease. The strongest benefits are seen on tests of long-term verbal memory, whereas minimal or no benefits are seen on other cognitive tasks, such as short-term memory and attention.

Few studies have looked at the effects of other sugars, including sucrose, on cognition. Yet, the limited data suggests that all carbohydrates improve memory similarly.

In addition to carbohydrate, the other macronutrients (protein and fat) have been shown to improve memory within 15 minutes of ingestion compared to placebo, however, carbohydrates appear to have a more prolonged effect, lasting up to an hour.

Long-term

Preventing a decline in glucose regulation may help prevent cognitive decline. Research has shown a relationship between poor glucose regulation, even in healthy young adults, and impairments in memory, as well as a strong relationship between type 2 diabetes and the development of dementia, including Alzheimer Disease. Thus, behaviours that improve glucose regulation and lower the risk of developing type 2 diabetes, such as exercise and a diet high in fibre and lower in fat, may also reduce the risk of cognitive decline.

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Mood

Research indicates that in healthy adults the effects of sugars and other carbohydrates on mood is minimal. Yet, there is some evidence that carbohydrates have a beneficial effect in people with depression, seasonal affective disorder, and premenstrual syndrome. These subjects are able to relieve symptoms by eating carbohydrates that they crave. One possibility for this may be that carbohydrate intake increases brain serotonin levels, which leads to improvements in mood. Unfortunately, this theory does not fully explain the effects. Others have suggested that the beneficial effects are related to the ingestion of any pleasant tasting food, rather than specifically to carbohydrates. More research is required to determine the long-term impact of carbohydrates on mood.

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Addiction

There is a popular belief that sugar consumption can lead to addiction similar to that of drug or alcohol dependency. In 2009, a scientific review conducted by Dr. David Benton from the University of Swansea, United Kingdom, examined the plausibility of sugar addiction in humans and its potential role in the development of obesity and binge eating disorders. Using an addiction model as a framework, a series of predictions were developed based on the hypothesis that an addiction to sucrose consumption can develop. Relevant scientific literature was examined in order to determine the validity of these predictions.

The findings of this review revealed that human studies do not support the widespread belief that sugar is addictive. The author found no support from the human literature that addiction to food, or specifically sucrose, plays a role in obesity and eating disorders. Key findings from the review include:

• The study of food preferences and cravings does not support a specific role for sucrose or sweet taste in increasing food cravings as an addiction model would predict;
• Fasting did not increase cravings for sweet items as would be expected in sugar addiction;
• Although there is a genetically determined liking for sweetness, individuals differ in their response to sweetness and preference declines with age, opposite to that predicted by the addiction hypothesis;
• Food cravings are commonly reported for a wide variety of foods, often reported as savoury/salty and sweet/fatty but most foods craved are high in fat rather than high in sugar;
• Obese individuals did not find sweetness alone to be particularly attractive or prefer sucrose-containing foods relative to other palatable foods;
• The notion that binge eating reflects an addiction to sweet foods is not supported by the evidence which indicates that a wide range of highly palatable foods are eaten during bingeing.

The author concludes that it is important to examine the underlying mechanisms of eating behaviour so that this knowledge can lead to appropriate interventions. If it is falsely believed that sucrose is addictive and leads to obesity, treatment may inappropriately concentrate on this ingredient while ignoring more beneficial responses.

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References

Carbohydrates in the Classroom, Canadian Sugar Institute, 1999

Carbohydrate, memory, and mood. Benton D. Nutrition Reviews 61:S61-S67, 2003.

Carbohydrates in Human Nutrition, FAO/WHO, 1998

Dietary carbohydrate, glucose regulation, and cognitive performance in elderly persons. Greenwood CE. Nutrition Reviews 61: S68-S74, 2003.

Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, Institute of Medicine, 2005

The effect of sugar on behavior or cognition in children. A meta-analysis. Wolraich ML et al. Journal of the American Medical Association 274:1617-1621, 1995.

Plausibility of sugar addiction and its role in obesity and eating disorders. Benton, D. 2009:Clin Nutr;   Dec.26.

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