9 January 2014
Despite the widespread recognition that many people in the UK need to cut down intake of added sugar to meet current recommendations, the recent media headlines describing sugar as a leading cause of obesity and diabetes and comparing it with tobacco are misleading. As health campaigners and industry continue to debate this issue, what does the science tell us? Are consumers being misled about the amount of sugar in foods and drinks?
Do we need to cut down on sugar?
Sugar is a type of carbohydrate that provides energy for the body in the form of glucose. In particular the brain needs glucose to function, as do muscles during exercise. Some sugars are found naturally in foods (e.g. fruit, vegetables and milk), while others are added during processing. These added sugars are known as non-milk extrinsic sugars (NMES). Foods that naturally contain sugars (e.g. fruits, vegetables, milk) typically provide other nutrients, such as vitamins, minerals or fibre, which are an important part of a healthy diet, whereas foods such as confectionery, biscuits and cakes, which can contain a lot of added sugars may provide calories without significant amounts of micronutrients. Consuming excess calories from sugar (or from any other source) can lead to weight gain over time, and frequent consumption of sugary foods and drinks can increase the risk of tooth decay. Therefore, it is important that we monitor our intake of sugars and avoid frequent consumption of foods and drinks that contain high amounts.
As a guideline, an average adult should consume no more than 90g of total (natural and added combined) sugars per day. Government advice states that NMES should provide no more than 11% of food energy intake (around 55g based on a 2000 kcal diet). As a population, our average intake of NMES exceeds the recommended level, especially in children. The National Diet and Nutrition Survey (2008-2011) showed that the highest intakes were seen in children aged 11-18 years, where mean intakes were 15.3% of food energy intake. However, levels have improved recently especially in the youngest age groups.
Does sugar cause obesity, diabetes and heart disease?
An excess of total calories (from any food or drink source), which is not balanced with sufficient physical activity, can lead to weight gain. Sugars are carbohydrates and like all carbohydrates, they provide a source of energy in our diet (4 kcal per gram or 16 calories per teaspoon). Although sugar provides less energy than fat (9 kcal per g), it can contribute to the energy density (calories per gram) of foods and drinks. The palatability of sweet foods and drinks (which may also be high in fat) can encourage overindulgence.
However, recent major reviews of the body of scientific evidence by Expert Committees have not found sufficient evidence of a direct link between total sugar intake and obesity or related conditions including diabetes, cancer and heart disease (http://www.nutrition.org.uk/nutritioninthenews/headlines/sugar). There is some evidence of a link between consumption of sugar-sweetened beverages and obesity.
Do foods contain ‘hidden’ sugars?
A wide range of different foods may contain sugars, either those that occur naturally in foods such as fructose in fruit or lactose in dairy products or those that have been added to foods during processing or preparation. This includes foods that may not be thought of as ‘sweet foods’ such as condiments, sauces and some soups, although some of these foods, such as condiments are consumed in small amounts so their overall contribution is small.
Foods containing fruit, such as juices, or milk will provide sugars because this occurs naturally in these ingredients, for example 100ml semi-skimmed milk contains 4.4g of sugars (lactose) and 100ml of unsweetened orange juice contains about 9g sugars (a mixture of glucose, fructose and sucrose). Dietary recommendations concern non-milk extrinsic sugars rather than naturally occurring sugars, although honey is usually included in the definition of non-milk extrinsic sugars as are fruit juices as the sugar has been released from the cellular structure of the fruit.
The most common sugars in foods are glucose, fructose, sucrose, lactose and maltose – collectively they are known as ‘sugars’. Sources of sugars that are added to foods will be included on the ingredients label (listed in order of weight) and the vast majority of foods sold in the UK already provide nutrition information on the back of pack (which will be mandatory under legislation now in place), which provides a figure for ‘carbohydrates – of which sugars’ (total sugars, which includes both naturally occurring and added sugars) in the food. In addition, many packaged foods have front of pack labelling showing the total sugars content of the food alongside a traffic light colour coding or a percentage of the reference intake for sugars. This means that sugars cannot be ‘hidden’ in pre-packed foods as they must be declared on food packaging.
In some instances foods and drinks are bought without packaging that provides nutrition labelling showing their sugars content, for example in coffee shops, cafes or restaurants. In such cases, it is important to be aware of the types of foods and drinks that can contain high levels of sugar and therefore calories, for example syrup-sweetened coffees.
Should sugar be compared to tobacco? Is it addictive?
The brain is dependent on a constant supply of glucose (approximately 120g per day) in order to function normally and prevent hypoglycaemia (very low levels of glucose in the blood). It is therefore not surprising that there is a basic biological drive to ensure that minimum requirements for carbohydrate are met. However, this does not qualify as evidence that sugar is addictive. Most experts agree that comparisons to the addictive behaviour associated with substances such as tobacco and alcohol are unhelpful (see http://www.nutrition.org.uk/bnfevents/pastevents/foodaddiction).
What are the major sources of sugar in UK diet
Most people have an intake of NMES higher than advised (11% food energy). According to the National Diet and Nutrition Survey (2008-2010), the major sources of NMES in the UK diet are:
- non-alcoholic beverages
- cereals and cereal products, and
- sugar, preserves and confectionery.
Soft drinks are the largest contributor to NMES intake for children aged 4 to 10 years (16% of total intake) and 11 to 18 years (29% of total intake).The largest contributor to intake of NMES in children aged 1.5 to 3 years is fruit juice (15% of total intake). Sugars, preserves and confectionery together contribute 24-27% of total intake in adults aged 19 and over, whereas cereal products, including buns, cakes, pastries and fruit pies, are the biggest contributor in adults aged 65 years and over (31% of total intake).
Although many of the recent media reports have highlighted bread as an important source of sugar, it contributes 8% of total sugars intake in UK adults. Breakfast cereals contribute 5% for adults and 8% for young children (4-10 years).
It should be emphasised that the sugars in fruit, vegetables and milk (and products made from them) come ready packaged along with beneficial micronutrients.
How should the food industry respond?
Sugars are widely used by the food industry not just for taste but also for colour, and adding bulk and thickness to food products. They also prevent mould forming and act as a preservative.
Reducing calorie intake and increasing physical activity is central to lowering risk of obesity and avoiding weight gain in the population. In the context of the obesity epidemic, reductions in the energy content of foods and drinks where possible is to be welcomed as this can contribute to reducing energy intakes, providing portion sizes don’t increase.
The Public Health Responsibility Deal food network has a calorie reduction pledge and, in some cases the calorie content of foods or drinks is being reduced by decreasing their sugar content, for example in soft drinks. The pledge also includes other activities like providing smaller portion sizes, changing the balance of foods and drinks offered to favour lower calorie options, and using education and promotions to encourage consumers to choose lower calorie options, which are widely available especially in the drinks sector.
In addition, a government-led front of pack labelling scheme, being widely adopted by retailers, includes the use of colour coding to highlight whether products are high, medium or low in a number of nutrients including sugars. This will also provide an incentive to reduce sugars content so that products can aim to be medium or low in sugars where possible rather than high.
However, there will be some foods and drinks in which sugars cannot be reduced, for example, where sugars occur naturally (e.g. fruit, milk) or where they are needed for functional purposes.