The scientific facts about sugars

The scientific facts about sugars

Carin Napier, Durban University of Technology
What is sugar?
Sugar is a macronutrient that provides energy to the body, but is not a source of micronutrients. Sugars are Dietary Carbohydrates and can be sub divided in to monosaccharides, disaccharides and polyols. In this short discussion we will concentrate on monosaccharides and disaccharides with glucose, fructose, galactose, sucrose, lactose and maltose as components. Fructose is a sugar found in fruit, honey and root vegetables. Galactose is a sugar present in milk and dairy products. Sucrose can be found in fruit and vegetables but is concentrated in sugar cane from which table sugar is extracted. Lactose is a natural sugar present in milk. Maltose is sugar present in malt products and some cereals used in the fermentation process.

What is the role of sugars in the body?
Most commonly used sugars contain glucose that is absorbed in the small intestine and the main source of energy for the body that is required for the brain and muscles to function.

Why do we eat sugars?
Sugars can be found naturally in all kinds of foods, it is often added to foods to improve the taste that may increase the intake of the food item, for example sweetened yogurt may help to increase calcium intake. Bland tasting breakfast cereals which are significant sources of nutrients become more acceptable if sugar is sprinkled over. Sugars added to food and those occurring in a natural form in the food are all metabolized in the same way in the body.

What is the maximum amount of sugars I can eat?
Due to limited scientific evidence linking higher sugar intake in the diet to a lower micronutrient intake, it has not been necessary to set an upper level intake of added sugar. A diet lower in sugars does not guarantee a higher intake of micronutrients. The World Health Organisation recommends that added sugar should not exceed 10% of total energy intake.

The role of carbohydrates and mental performance
The brain is the only carbohydrate dependent organ in the body. The Dietary Reference Intakes (DRIs) for carbohydrates has been calculated by the Institute of Medicine (IoM) as 130g per day. This is minimum required for optimal brain function for children and adults.

Sugars and hyperactivity
Various studies over decades have confirmed that there is no direct link between hyperactivity and sugar consumption. Many studies published made in clear that sucrose had no effect on child behaviour. A diet low in nutrients and energy can lead to poor test performance, therefore it is recommended that good dietary habits are the best way to ensure optimal mental and behavioural performance.

Sucrose and dental caries
Anderson (2009) reported that out of over 1856 different published research papers it has been concluded that there are no reliable relationship between quantity of sugar consumed and dental caries. Out of these a limited number of the papers linked frequent use of sugar to dental caries. Baked goods and snack items were however positively linked to the disease. Good oral hygiene is of importance to prevent dental caries.

The role of sugars in the development of disease
The American Heart Association acknowledged that it is unlikely that a single food is responsible for obesity. Various studies have also indicated that dietary sugars are not an independent risk factor in chronic diseases.

The role of sugar in weight management
For weight management balancing energy intake with physical activity is critical regardless if the energy source is dietary fats, protein or carbohydrates. It is probable that when fat in the diet is replaced by carbohydrates in the form of sugars or complex carbohydrates it can lead to a lower body weight. When sugars are consumed as part of a balanced diet and in moderation it is unlikely that it will result in overweight.

The diet should consist of nutrient dense foods with variety, balance and moderation to improve and maintain health.

References
Livingstone M.B.E. and Rennie K.L. 2009. Sugars and micronutrient dilution. Obesity reviews, 10(1): 34-40
Van Baak M.A. and Astrup A. 2009. Sugars and body weight. Obesity reviews, 10(1): 9-23
International Food Information Council Foundation. 2010. The science of sugars. Washington DC
International Food Information Council Foundation. 2010. The truth about sugars, 10 facts you may not know. Washington DC
World Health Organisation/ Food and Agricultural Organisation. 2003. Diet, nutrition and the prevention of chronic diseases. WHO technical report series 916. Geneva.