People all around the world eat sugar as part of a healthy, nutritious and balanced diet. Many people worry that eating sugar may be bad for their health. Their concern is unnecessary as extensive research has not been able to link the consumption of sugars to any chronic disease except dental caries (tooth decay). And even though dental caries has been associated with sugar consumption, there are many other factors (including the consumption of other carbohydrates and oral hygiene) that play an important role in the development of caries.
1 : What are sugars?
Sugars are a class of carbohydrates and thus one source of food energy. Carbohydrates can be divided into 3 different groups, namely: sugars; oligosaccharides and polysaccharides. Sugars can be further divided into 3 classes: monosaccharides; disaccharides and polyols.
Monosaccharides are single unit sugars. Those commonly found in food are:
- glucose (often called blood sugar when talking about blood glucose)
- fructose (one of the main sugars found in fruit – the others are sucrose and glucose)
- galactose (found in milk)
Disaccharides consist of two monosaccharides linked together. Those commonly found are:
- sucrose (table sugar) = glucose + fructose
- lactose (milk sugar) = glucose + galactose
- maltose (malt sugar) = glucose + glucose
References to "sugar" usually mean sucrose or table sugar, while references to "sugars" means any combination of mono-, di- and oligosaccharides.
2 : Sources of sugars?
Sugars are found naturally in many foods. For example:
||Fruits, vegetables, table sugar, honey, milk products, cereals
||Fruits, vegetables, honey
||Fruits, vegetables, table sugar, honey
||Malt products, some cereals
3 : Uses of sugars
Some uses of sugar are listed below:
3.1 Sugar as a source of energy
Sugar is an important source of food energy. During digestion, all food carbohydrates (starches and sugars) break down into single molecule sugars. These sugars are absorbed from the intestine into the blood stream and travel to the cells, where they are used to provide energy for cellular functions. In parts of the world where people suffer from energy malnutrition and are undernourished, sugar is valued as an inexpensive source of energy to support human activities.
3.2 Sugar as a source of income
Sucrose is stored in large quantities in sugar cane and sugar beet plants. After it has been separated from its plant materials it can be purified to produce sugar on a commercial scale. Sugar beet grows in cooler climates unsuitable for sugar cane. Sugar cane is a major agricultural product and important source of revenue for many developing countries.
3.3 Function of sugar in foods
Sugars have a number of functions in the preparation of foods, such as improving taste and texture. Important uses of sugars in food include:
- Providing sweetness
- Serving as preservatives in jams and jellies
- Increasing the boiling point or reduces the freezing point of foods
- Allowing fermentation by yeast
- Reacting with amino acids to produce colour and flavour compounds important to the taste and golden brown colour of baked goods.
- Making foods that have limited moisture content crisp
3.4 Medical uses of sugar
Table sugar can be used to make oral rehydration solution (ORS), which can help prevent dehydration in children who have infantile diarrhoea or vomiting in developing countries. The effective use of ORS saves millions of lives around the world each year. Although recipes for ORS vary from country to country, one widely used recipe is made up of 1 litre of water, 8 teaspoons sugar and ½ teaspoon of salt.
3.5 Sugar and fortification
Fortification of foods with micronutrients is generally recognised as the most cost-effective long-term strategy for eliminating micronutrient malnutrition. It is also socially acceptable, requires none or little change in food habits and characteristics, and provides a means for reaching the greatest percentage of the population requiring the micronutrients. Sugar is a safe and economical foodstuff that is accepted and consumed by populations at risk including those who are very poor. So fortified sugar can play a critical role in fighting nutrient deficiency.
Sugar is used as a vehicle for supplying vitamin A in a number of Central American countries (Guatemala, Nicaragua, Honduras and El Salvador), in Zambia and more recently in the Philippines. Pilot studies have also been conducted in other developing countries such as India and Vietnam. The consumption of fortified sugar has resulted in significant increases in vitamin A intake and improvements in the vitamin A status of a surveyed population in Guatemala. Vitamin A fortification can significantly reduce the risk of a permanent form of child blindness and mortality from severe infections in undernourished children.
3.6 Industrial uses of sugars
Sugars are also used in the production of surfactants, fabrics, cement.
4 : Consumption of sucrose
4.1 How is sucrose consumption measured?
When people look for an estimate of sucrose intake, they often use statistics called "per capita disappearance" or "sugar available for consumption". Availability data are reported as kilograms of sugar per person per year by dividing the amount of sugar produced in a country (plus its imports and minus its exports) with its population. It is misleading to use this method to estimate how much sugar people actually eat without adjusting for the amount of sugar wasted, or used in making foods like bread and wine or used for non-food uses of sugar (eg pet foods, fabrics, cement).
4.2 How much sucrose should people eat?
A wide range of sugar intake is compatible with a balanced diet and sugar must be seen as one food source of carbohydrates. All the carbohydrates that a person eats should supply more than half of the energy in the diet.
Some people theorise that people who eat large amounts of sugar may not be getting enough vitamins and minerals in their diet and sugars are often criticised as "empty calories" thought to displace nutrients from the diet. This theory is called micronutrient dilution or micronutrient displacement. Whilst refined sugar contains only carbohydrate, there appears to be a wide range of sugar intakes over which nutrient adequacy of the overall diet is not compromised. High sugar consumers do not generally have lower intakes of vitamins and minerals than low sugar consumers.
According to the Food and Agriculture Organisation of the United Nations (FAO), the key to getting the best from your food and choosing a diet with the optimum nutritional benefit is to:
- Eat a variety of foods
- Eat to meet your needs - that is, those who do a lot of physical activity and so use up a lot of energy should take in more energy than those who don't do much physical activity
- Protect the quality and safety of your food
- Keep active and stay fit
5 : References
Bolton-Smith C (1996) Intake of sugars in relation to fatness and micronutrient adequacy. International Journal of Obesity 20(Suppl 2):S31-S33
FAO Nutrition Manual. Get the best from your food. http://www.fao.org/docrep/x0242e/x0242e00.htm
Food and Agriculture Organisation / World Health Organisation Expert Consultation (1998) Carbohydrates in Human Nutrition. FAO Food and Nutrition Paper No 66. FAO, Rome
Food and Nutrition Board (FNB) / Institute of Medicine (IOM) (2002) Dietary reference intakes for energy, carbohydrates, fiber, fat, protein and amino acids (Macronutrients) USA. National Academic Press Ch 6, p25 and p42
Ribaya-Mercado JD, Solomons NW, Medrano Y, Bulux J, Dolnikowski GG, Russell RM, Wallace CB (2004) Use of the deuterated-retinol-dilution technique to monitor the vitamin A status of Nicaraguan schoolchildren 1 year after initiation of the Nicaraguan national program of sugar fortification with vitamin A. American Journal of Clinical Nutrition 80(5):1291-8