I can remember a time when some people were calling sugar 'pure, white and deadly', yet there seems to be little fuss about sugar now. Just what is the current position on the relationship between sugar and health generally?

Introduction – Sugar in the Diet

Sugar is the commonly used term for sucrose, a naturally occurring ‘simple’ carbohydrate (see the Appendix for definitions of ‘simple’ and ‘complex’ carbohydrates, and the place of sucrose alongside other sugars). This FAQ also uses the word ‘sugar’ to refer to sucrose.

In Australia, nearly all sugar has been extracted from farmed sugar cane. Extracts include raw, brown, caster and white sugar, molasses and plain syrup. Contrary to popular opinion, all these forms of sugar (and honey) provide similar nutrition—none is a source of essential nutrients such as vitamins and minerals, or of dietary fibre.

As applies to all ingested carbohydrates, sugar is broken down by the digestive processes to release even simpler carbohydrates, including glucose. Glucose is normally the brain’s only source of energy, and also the muscles’ preferred source of energy for vigorous physical work.

However, there is no need to eat sugar to obtain all the glucose the brain and muscles need. Complex carbohydrate foods such as bread, rice and pasta (preferably wholegrain), legumes (peas, beans, lentils and so on) and potatoes will achieve this, while also providing vitamins, minerals, protein and dietary fibre. Fruit and milk products (especially low- or reduced-fat) also provide essential nutrients along with some carbohydrate. The Australian dietary guidelines include “Consume only moderate amounts of sugars and foods containing added sugars”. [For access to all the Dietary Guidelines for Australians, go to: http://www.nhmrc.gov.au/publications/synopses/dietsyn.htm ]

Although sugar may be added at the time of consumption (e.g. to breakfast cereal, tea, coffee), it is more often ‘hidden’ in manufactured foods such as cakes, biscuits, pastries and soft drinks. Because consumption of these products is rather high in Australia, excess sugar intake is more likely to be via these foods/drinks rather than through sugar added at the time of consumption.

Sugar and Health

Type 2 Diabetes

People with type 2 diabetes have an impaired ability to handle the sugars (including glucose) that are absorbed through the intestine following the breakdown of carbohydrate. As a result, the level of glucose in the blood can build up to dangerous levels.

The rate at which a carbohydrate food releases glucose into the body is called the ‘glycemic index’, abbreviated to GI, and it is now believed that the slower-releasing sources of carbohydrate (i.e. those with lower GI) are generally more health promoting. [see the FAQ in this series on ‘Glycemic Index’ for more on this]. In summary, the lower the GI, the more slowly the food is absorbed and so the more time the body has to cope with the incoming carbohydrate.

Therefore, low GI foods are believed to be better than high GI foods at allowing people with diabetes to maintain an appropriate blood glucose level. It is also widely believed that basing the diet largely on foods with low GI will reduce the risk of developing diabetes in the first place.

Contrary to popular belief, sugar itself has only a moderate GI compared to other foods, so it is by no means the most rapidly absorbed carbohydrate. In fact, some foods that were previously considered to be more appropriate than sugar in the 'diabetic diet' are absorbed more rapidly than sugar, leading to a greater 'assault' on the body's ability to cope with absorbed carbohydrate. Potato chips, mashed potato, baked potato, non-wholegrain and non-sourdough breads, and some breakfast cereals (e.g. Coco Pops, Cornflakes and Rice Bubbles) all have higher GI than sugar.

One problem with high sugar consumption is sugar’s tendency to raise the level of triglycerides in the blood. This effect is thought to be primarily due to the fructose present in sugar. High triglyceride levels are common in people with type 2 diabetes and are a risk factor for coronary heart disease. High sugar intakes may further increase this risk. However, moderate intakes are unlikely to be a cause for concern.

According to the Expert Dietary Guideline Panel (2003): “Development of type 2 diabetes does not appear to be related to ingestion of sugar or other carbohydrates: it is predominantly influenced by genetics, body weight and lifestyle factors”.

It therefore appears that there is a place for sugar, in moderation, in the diet of people with diabetes. However, high intakes of sugar are not recommended. [For more on this, see the Detailed FAQ on Diabetes in this series].

Overweight/Obesity

In relation to weight control, it has been reported that a 'sugar/fat seesaw' effect exists; that is, people who eat more sugar usually do so at the ‘expense’ of eating less fat, while high fat consumption is often accompanied by low intake of sugar. It has also been reported that people who are above their optimal body weight tend to eat more high-fat food and less food containing sugars than normal weight people. So a high consumption of sugars may be a marker for a generally lower fat diet.

Of course, this should not be used as an excuse to eat more sugar! It is important to stress that excess energy in any form will promote the accumulation of excess body fat. However, many sugary foods (e.g. soft drinks, pastries, biscuits and cakes) are of low nutritional value. They are also often significant sources of saturated fat, and therefore should be eaten only as occasional treats.

In the context of weight control, there are other good reasons for limiting sugar intake. After eating a meal or snack that is rich in carbohydrate, the body will increase its use of glucose as the major source of energy. If the quantity of glucose entering the body is greater than that needed to fuel the body’s metabolism over the next few hours, some of the excess glucose will be stored in the liver and muscles. The remainder may be converted into fat, and this seems to apply especially to people who already have excess body fat. In other words, excess sugar in the diet can actually add directly to body fat, i.e. it can promote obesity.

But even if the excess glucose isn’t converted to fat, its presence will inhibit the body’s use of its own fat stores to meet energy needs; after all, why would the body go through the more difficult process of extracting energy from its fat stores if plenty of glucose is already available in the bloodstream! This means that even if excess sugar in the diet isn’t converted to fat, its presence in the body discourages the use of body fat as a source of energy, so high sugar intake can help maintain excessive body fat levels.

As a result of this potential to aggravate overweight/obesity, excess sugar in the diet has been implicated as a possible contributor to conditions that are associated with excessive body fat, including increased risk of heart disease and diabetes.

Heart Disease

According to the Expert Dietary Guideline Panel (2003) “There is no evidence of a causal role for sugar in the development of cardiovascular disease. Ensuring that the diet contains adequate amounts of fruit, vegetables and carbohydrate-rich foods – at the expense of fat – and maintaining a healthy body weight are the basis of dietary advice aimed at reducing the risk of cardiovascular disease”.

However, as mentioned above, although sugar has not been directly implicated in heart disease, excessive consumption may increase the risk through promoting or maintaining overweight/obesity. Also, as discussed in greater detail above, there is some evidence that high sugar intakes may raise the level of blood triglyceride (an independent risk factor for heart disease). So for people at greater risk of heart disease (e.g. people with diabetes) or those who have high blood triglyceride levels (as determined by their doctor), moderating sugar intake may be especially beneficial.

Tooth Decay

It has been demonstrated unequivocally that consumption of sugar is associated with increased risk of tooth decay.

In this regard, it should be noted that 'sugars' (including those that occur naturally in fruits and in honey) all promote tooth decay, although to varying degrees. In fact, all carbohydrates that come in contact with teeth have the potential to increase acid levels in saliva (resulting from the action of bacteria in plaque), leading to decay.

Although other carbohydrate foods may contribute to tooth decay, because of its high levels of consumption sugar is one of the major components of the diet contributing to dental problems.

The risk of tooth decay can be reduced by consuming high carbohydrate foods or beverages only as part of a meal (rather than as between-meal snacks) and then allowing a period of two hours (or more) before eating again. This will greatly increase the likelihood that the teeth will have time to recover before they are again exposed to carbohydrate. (It also means that high calcium foods such as low- or reduced-fat milk and milk products—especially those that do not contain added sugar—are ideal snacks in this period between meals).

It is also true that 'liquid' forms of sugars (i.e. sweet drinks) are less likely to promote tooth decay than are solid forms (e.g. confectionery, dried fruits, chips, biscuits and muesli bars), with 'sticky' solid forms (e.g. toffee) being possibly the worst of all for teeth. This is because the liquid forms are more readily washed from the teeth, while sticky, solid confectionery tends to cling to the teeth, allowing bacteria to convert the sugars into the acid that attacks the tooth enamel.

However, acidic drinks—such as most sweetened, carbonated soft drinks, many ‘diet’ soft drinks, sports drinks and fruit juices—pose another threat to teeth: ‘dental erosion’. This can occur if acidic drinks are sipped over long periods, rather than drunk reasonably quickly. By continually ‘bathing’ the teeth in acid, much of the enamel can be permanently lost. This means that it is better to finish drinking your sports drink, fruit juice or other acidic drink within a few minutes of starting drinking. If plain water is available, a water rinse following the sweet drink will help to wash any remaining sugar and acid from the teeth and will therefore further reduce the risk of both tooth decay and dental erosion.

Obviously, there are other important non-dietary factors for good dental hygiene, including brushing teeth at least twice a day after meals with fluoridated toothpaste and/or chewing sugar-free gum for 20 minutes, regular visits to the dentist, and drinking fluoridated water.

What are suitable alternatives to sugar?

Nutritious alternatives to sugary snacks include fresh and dried fruit, crisp vegetables (e.g. carrots and celery) with low-fat dips, cherry tomatoes, and low-fat dairy products (e.g. low-fat yogurt). Honey, can be used as an alternative to sugar to sweeten foods (but note that nutritionally, other than having a slightly lower GI than white sugar, honey is really just another form of ‘sugar’). Bread with jam, honey or banana (or honey and banana) is another suitable snack food, especially for hungry children. Fruit smoothies are also popular with people of most ages.

Are there any situations where you would recommend eating sugar?

When eaten in moderation, sugar can be part of a health-promoting diet.

Sugar, honey or preserves can all be used to help improve the taste and acceptability of high carbohydrate nutrient dense foods and help to increase overall nutrient intake.

An example of appropriate use of sugar might be offering children flavoured reduced- or low-fat milk, or showing them how to make a ‘skinny’ milkshake or fruit smoothie. Lightly sprinkling sugar, or pouring a small amount of honey on unflavoured low- or reduced-fat yoghurt, on fruit salad or on breakfast cereal will often encourage consumption of these nutritious foods. Spreading jam or honey on wholegrain bread, toast, crumpets or pikelets will encourage children (and adults) to eat more of these nutritious grain foods.

If the individual controls the amount of sugar that is added (e.g. to Weet Bix, Vita Brits), less sugar may be used than is found in many pre-prepared foods (e.g. Coco Pops and Fruit Loops).

Active people, such as endurance athletes can also benefit from using sugar (or foods/beverages with added sugar) as sources of ‘instant energy’ during the event or training session, and also to replenish muscle carbohydrate reserves soon after completion of sustained vigorous activity.

For more information Nutrition Australia recommends:

• Diet and Dental Caries
• Weight for a Change
• Eating Activity Sport and You

Appendix: Definitions of ‘Simple’ and ‘Complex’ Carbohydrates

For many years, nutritionists divided carbohydrates into ‘simple’ carbohydrates (sugars) and ‘complex’ carbohydrates (starchy foods).

Simple carbohydrates include sucrose (commonly known, rather confusingly, as ‘sugar’), glucose, fructose (the most common sugar in fruit), and lactose (in milk). Honey is a mixture of several sugars, including fructose, glucose and sucrose. Simple carbohydrates are generally sweet.

Starch consists of many molecules of one type of sugar (glucose) chemically bound together. Bread, rice and potatoes are examples of complex carbohydrate foods. Complex carbohydrate is not sweet.

As discussed above, a new approach is emerging to the classification of carbohydrates with respect to their nutritional effects. This is the glycemic (also spelled glycaemic) index, abbreviated to GI. For more on GI see the FAQ on ‘Glycemic Index’ in this series.

View the summary FAQ on sugar.

Back to Frequently Asked Questions Index

Disclaimer: This material is provided on the basis that it constitutes advice of a general nature only. It is not intended to replace the advice of a physician or a dietitian.