What is sugar?



Sugar or sugars?


The term ‘sugar’ is generally understood to refer to table sugar – sucrose – the type of sugar which we add to our tea or use in baking.  It is naturally-occurring and is extracted from sugar beet and sugar cane.

Sugars’ are carbohydrates – the starches and sugars in our diet which provide fuel (energy).  The term ‘sugars’ covers the full range of mono– and disaccharide molecules, for example, fructose, sucrose, glucose, lactose and maltose.  They occur naturally in fruits, vegetables and dairy, as well as being an ingredient used in a wide range of foods and drinks.  Nutrition experts recommend that adults and children aged two years and above obtain approximately 50% of their daily calories from a variety of carbohydrate sources*.  The bulk of these should come from starch-rich foods including bread, rice, pasta and other wholegrain and high fibre sources.

Starch consists of hundreds of molecules of glucose joined together. When starch is digested, it is broken down into maltose and glucose.

Use these links for more information about a healthy diet and the eatwell guide.

Did You Know?: Sugars and starches provide four Calories per gram.
Did You Know?: In the UK the main source of carbohydrate in the diet is bread*

* SACN (2015) https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/445503/SACN_Carbohydrates_and_Health.pdf 
(accessed 21/07/15)

The science ...


The most common sugars in the diet fall into two main categories:

and disaccharides

Monosaccharides (‘Mono-‘ = one) are single molecules of sugar. The most common monosaccharides in the diet are: glucose, fructose and galactose

  • Glucose (dextrose) is a monosaccharide found in many plants and is a component of most carbohydrate foods including sugars and starches.  Glucose is important as most carbohydrates are eventually digested or converted into glucose by the body for fuel.  
    • Occurs naturally in: fruits and vegetables
    • Used in: confectionery and baking (as glucose syrups)
  • Fructose  (also known as fruit sugar) is a monosaccharide.  It is mostly converted into glucose by the liver
    • Occurs naturally in: fruits, vegetables, honey
    • Used in: fruit preparations and dairy products
  • Galactose part of lactose, the sugar found in milk

Did You Know?: The brain requires approximately 130g carbohydrate each day to meet its glucose needs*

Disaccharides (‘Di-’ = two) are two linked sugar molecules which are broken down into the monosaccharides by digestion. The disaccharides are: sucrose, lactose and maltose

  • Sucrose = glucose + fructose
    Also known as table sugar (such as granulated, caster or demerara sugar).  Extracted from either sugar beet or sugar cane and often referred to as ‘added sugars’
    • Occurs naturally in: sugar beet, sugar cane, plants, fruits and vegetables
    • Used in: confectionery, cakes, biscuits, jams and preserves
  • Lactose = glucose + galactose (the milk sugar)
    • Occurs naturally in: milk and dairy products
    • Used in: dairy and dry mixes such as instant soups
  • Maltose = glucose + glucose
    Formed when starch is broken down
    • Occurs naturally in: germinating seeds such as barley
    • Used in: malted drinks and beers, glucose syrups for confectionery and baking

* EFSA (2010) Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre.  EFSA Journal 8(3): 1462

Where does table sugar come from?


Sugar is produced in plants, either sugar cane or sugar beet, by a process known as photosynthesis.  The juice is extracted from the sugar beet or cane and impurities are removed. It is then crystallised into white sugar, which is 99.95% sucrose. Sugar is identical whether it comes from beet or cane but the climate of a geographical region is the prime influence on which is grown.

Sugar Cane – key facts:

  • Sugar cane is a member of the grass family and grows to five metres in height
  • Found in the tropical and semi-tropical climates of the world where it is hot and sunny all year with heavy seasonal rainfall – conditions in which the plant thrives

Sugar Beet – key facts:

  • Sugar beet is a large off-white root crop similar to the parsnip
  • Grows in the temperate climate of Europe and North America

See our Production of Sugar section for more information

Different types of sugar


The most obvious difference between types of sugars used in the home is colour.  When sugar has been extracted from the juice of the beet or cane plant, a strong tasting black syrup (known as molasses) remains.

When white sugar is made, the molasses are entirely removed, whereas brown sugars retain varying amounts of this natural coloured and flavoured syrup. The more molasses in brown sugar, the stickier the crystals, the darker the colour and the stronger the flavour, for example, muscovado sugar.  However, the presence of molasses does not change sugar’s nutritional value.

These commonly-used sugars vary in colour, flavour and crystal size:

  • Granulated: all-purpose sugar for general use (‘table’ sugar)
  • Caster: small grains ensure smooth blending to give even textures in cakes and other baked foods
  • Icing: milled sugar to give a fine powder.  This provides texture to icings and buttercreams – useful for decorating cakes
  • Demerara: a brown sugar with larger grains providing crunch and flavour – ideal for use in biscuits and crumbles

Did You Know?: A level teaspoon of sugar (4g) provides 16 Calories

Glycaemic Index and Glycaemic Load


Most carbohydrates will end up as glucose to provide that vital energy, as it is absorbed more quickly than other sources of energy such as fat or protein.

The Glycaemic Index (GI) is a measure of blood glucose response to foods after eating (postprandial glycaemic effect).  The effects of carbohydrate-containing foods are measured against the same quantity of a reference source, usually 50g of glucose (GI 100)*, and ranked according to how quickly glucose is released, from slow-release (low GI) to quick-release (high GI).

Many factors can affect GI.  This can include cooking method, how the food is stored or processed and other components of the food, for example, moisture content or ripeness of a fruit*.  The matrix of a food can also affect the rate at which glucose is absorbed.

Foods with a high GI aren’t necessarily bad for you, just as those with a lower GI may not necessarily be better for you.  Eating lower GI foods can help regulate blood glucose levels but it is important to ensure balance to maintain energy levels.

GI table (3)   

Glycaemic Load (GL) is a measure which takes into account the quantity of carbohydrate in a food and its GI value to indicate the overall effect of a portion of food on blood glucose levels*

GL can be calculated as follows:

GI x Carbohydrate (g) content per portion ÷ 100

For example: 1 apple
GI of 36 x 15g carbohydrate per portion ÷ 100
= GL of 1 apple is 6 (low)

For more information, visit the Glycemic Index Foundation

* Foster-Powell,K; Holt, Susanna HA; Brand-Miller, Janette C (2002) International table of glycemic index and glycemic load values. Am J Clin Nutr 2002;76:5–56

What is sugar used for?


Sweetener: sugar is added to foods or drinks to make them taste more pleasant. For example, to balance the bitterness of coffee or reduce the tartness of sour fruit

  • Preservative: sugar is a natural preservative that is highly soluble and prevents the growth of micro-organisms, thereby reducing food spoilage, such as in chutneys
  • Texture: sugars give texture to a variety of foods, for example, cakes or crunch in biscuits
  • Enhance look and taste: sugar can improve the look and flavour of food, including its colour.  This increases palatability and may help to widen the range of foods that are consumed.  For example, breakfast cereals or baked goods


Did You Know: Jams must contain at least 60% sugar to comply with food standards regulations in England*

* Food Standards Agency – Jam and Similar Products (England) Regulations (2003)

Food labelling


food labelInterpreting food labels can be confusing. By law, manufacturers are now required to list all ingredients on food labels, with ingredients shown by weight in descending order1. Nutrition labelling also includes values for both carbohydrates and sugars2.



How are sugars labelled?
Despite common perceptions, ingredients cannot be ‘hidden’ in our food. They may, however, be listed in different ways. The list below highlights some of the more common terms for sugars:  

  • Invert sugar syrup mixture of glucose and fructose, obtained from the hydrolysis of sucrose
    • Used in: confectionery, baked goods
  • Honey made by bees as food for the hive. It contains fructose and glucose and is a popular ingredient due to its unique taste
    • Used in: snack bars, cakes
  • Molasses/treacle viscous syrup that is a by-product of extracting sucrose.  Contains sucrose, glucose and fructose
    • Used in: variety of foods including gingerbread
  • Agave syrup extracted from the agave plant, this primarily contains fructose and some glucose
    • Used in: drinks, confectionery, cakes
  • Fruit juice concentrates provide a source of fructose, glucose and sucrose
    • Occurs naturally in: a wide range of different fruits, such as grapes, apples, dates or prunes
    • Used in: to sweeten drinks, biscuits, cakes
  • Isoglucose is a glucose-fructose syrup, comprising approximately 42% glucose and 58% fructose
  • High fructose corn syrup (HFCS) or fructose-glucose syrup. Comprises approximately 55% glucose and 45% fructose and is extracted from corn. It receives a lot of media attention and is commonly used in America. However it is not commonly found in UK foods due to EU quotas and currently accounts for only 5% of sweeteners3
    • Used in: cakes, cereals, fruit products, drinks

Label claims such as ‘no added sugar’ indicate foods where sugars, i.e. mono-or disaccharides, have not been added. However these foods may still taste sweet due to naturally-occurring sugars. ‘Low sugars’ or ‘sugars-free’ claims can only be made where foods contain no more than 0.5g of sugars per 100g or 100ml4.

Other sugars terminology may include:

  • Non-milk extrinsic sugars (NMES)
    • Sugars not contained within the cellular structure of a food. It includes sugars in unsweetened fruit juice and honey, as well as sugars that are added to food and drink but excludes sugars in milk and milk products. It also includes 50% of the weight of sugars found in dried, stewed or canned fruit5
  • Added sugars 
    • Sucrose, fructose, glucose, starch hydrolysates (glucose syrup, high-fructose syrup, isoglucose) and other isolated sugar preparations used as such or added during food preparation and manufacturing6
  • Free sugars         
    • Monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates7
  • Sugars   
    • This indicates the ‘total sugars’ content of a foodstuff, including both mono- and disaccharides, whether added by the cook or manufacturer or naturally occurring.

1 Regulation (EU) No 1169/2011 of the European Parliament and of the Council http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011R1169 (accessed 25/06/15)
2 FDF (2015) https://www.fdf.org.uk/keyissues.aspx?issue=628 (accessed 15/07/15)
3 European Food Information Council (2015)
http://www.eufic.org/page/en/page/FAQ/faqid/glucose-fructose-syrup/ (accessed 25/06/15)
4 Europa (2015)
http://ec.europa.eu/food/food/labellingnutrition/claims/community_register/nutrition_claims_en.htm#9 (accessed 25/06/15)
5 COMA (1989) Dietary Sugars and Human Disease. Report on Health and Social Subjects. No 37, HMSO, Department of Health, London
6 SACN (2015) Carbohydrates and Health Report
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/445503/SACN_Carbohydrates_and_Health.pdf (accessed 23/11/15)
7 WHO (2015) Guideline: Sugars intake for adults and children
http://apps.who.int/iris/bitstream/10665/149782/1/9789241549028_eng.pdf?ua=1 (accessed 25/06/15)

Health professionals

History of Sugar