Why is sugar regarded as 'empty kilojoules'?

Unlike other foods, sugar supplies energy only, which is why it is often accused of providing 'empty kilojoules'. The underlying fear is that if you eat a lot of sugar, you may leave out more nutritious foods, to the extent that your diet may be deficient in nutrients such as minerals and vitamins. However, studies of nutrient intakes have shown that this is not necessarily the case. There is in fact no evidence that people who eat a lot of sugar are more likely to suffer from nutrient deficiencies than those who eat very little.

The explanation for this apparent contradiction lies in the composition of the diet as a whole. Generally speaking, sugar consumption rises with income (up to a point), therefore people whose diets contain relatively large amounts of sugar also tend to eat large amounts of a wide variety of other foods, so it is unlikely that they will suffer from nutrient deficiencies. Incidentally, it is important to realise that when referring to sugar consumption we are talking not so much about `sugar bowl' sugar as about that contained in processed foods, desserts, and so on - in other words, in the diet as a whole.

Another interesting point here is the apparent inverse relationship between sugar and fat in the diet - described by some authors as the 'Sugar:Fat See-Saw'. Recent studies have shown that in certain populations, people who eat less sugar tend to eat more fat and vice versa. What these studies also revealed was that those who ate more sugar but less fat were taking in more of other essential nutrients and fibre as well.

The conclusion that can be reached from all this is that there is no direct relationship between the amount of sugar you eat and the overall quality of your diet. Far more important is the composition of the diet as a whole. Obviously, excessive sugar intake should be avoided, but if you are aiming to improve the nutritional value of your diet it would

be better to examine what you eat in total and make all-round improvements, than to focus on the elimination of a single foodstuff such as sugar.

The 'pure, white and deadly' tag

In the past few decades there has been an alarming increase in the incidence of so-called Western diseases such as heart disease, cancer, diabetes, hypertension and certain gastro-intestinal disorders. In the search to find out why this was happening, attention naturally focused on diet, since this was one of the areas that had undergone remarkable changes. Amongst other things, one aspect of the average diet that had changed was sugar intake.

In the early days sugar was a rare commodity out of the price range of most people, but as it became increasingly available, it was eaten in greater quantities by more and more people. Recognition of this fact led to a series of investigations in which sugar intake was compared with the incidence of various diseases and in many cases, the relationship seemed obvious - hence the claim made in the 1970's that sugar was 'pure, white and deadly'. However, in drawing simple comparisons such as these it is both easy and tempting to ignore the many other factors that could influence the outcome. In the years that have elapsed since these claims were first made, a great deal of research has been done on the causes of these diseases and we are now better able to identify those to which sugar may genuinely be linked.

Sugar and diabetes

Diabetes (or more correctly, diabetes mellitus) is a very complex disorder and neither its causes nor its treatment are as yet fully understood. For many years it was believed that eating too much sugar caused diabetes, but this theory has now been discounted. The cause is not yet known, although it is accepted that obesity is a contributory factor. Recent years have seen a considerable shake-up of traditional views on the treatment of diabetes. Nowadays, the diet recommended for diabetics is high in complex carbohydrates and low in fat. Some experts believe that a small quantity of simple carbohydrate can also be included, provided the condition is well-controlled and the intake of fibre sufficiently high. This is however controversial and no diabetic should eat sugar without the go-ahead from his or her doctor and/or dietitian.

Sugar and heart disease

The subject of diet and heart disease continues to be controversial and although there seems to be little doubt that the amount and type of fat you eat is important in determining your risk of having a heart attack, no such link has been confirmed for sugar. However, a small proportion of people are particularly sensitive to carbohydrate - for them, eating large quantities of sugar can result in a higher level of fat in the blood so sufferers of this condition should reduce their sugar intake to a minimum. This is generally referred to as 'carbohydrate sensitivity', a term used to describe a condition where serum triglyceride levels are elevated and the insulin response to a sucrose load is accentuated. The condition can only be diagnosed by a doctor with the aid of certain blood tests.

Sugar and dental decay

There are several factors involved in the development of dental caries (tooth decay), including heredity, oral hygiene and of course, diet. The role played by diet is more complex than you might think - it is not only what you eat that's important, but also how you eat it. The adhesiveness (stickiness) or abrasiveness of specific foods is yet another factor.

It is common knowledge that sugar contributes to dental decay, but perhaps less well-known is the fact that this applies to all fermentable carbohydrates, including those that don't even taste sweet (such as sausage rolls or potato chips). Research has shown that perhaps the most important thing to consider in terms of diet and dental caries is how often you eat cariogenic (caries-producing) foods such as those containing sugar. To help prevent caries, these foods should be eaten with meals rather than in between. This is because tooth decay is caused by acid-producing bacteria present in the mouth. Each time cariogenic foods are eaten, acid is produced, so it follows that the more often you eat these foods, the greater the likelihood of caries developing. In addition, try to choose foods that are easily chewed and swallowed - the longer the food stays in your mouth, the more likely it is to cause trouble. Boiled sweets that are sucked slowly, or foods that leave bits stuck to the teeth (such as biscuits or dried fruit) are particularly cariogenic.

Interestingly, some foods act as 'buffers' and counteract the harmful effects of other foods on the teeth. These include nuts and certain cheeses (for example, mature Cheddar, Gouda, blue Brie and Mozzarella). Such foods cause less acid to be produced than does cariogenic food. So the long-standing tradition of following a sugary dessert with cheese is highly recommended, at least as regards dental health!

Overweight and Cholesterol intake in your diet

The effect of dietary cholesterol on cholesterol levels in the blood is less crucial and more variable among individuals than the effects of saturated fat - nevertheless, it plays an important contributory role and this is why the recommended limit for cholesterol consumption has been set at 300 mg per day. Of course, the average person has no means of measuring the amount of cholesterol in various foods, but what you can do is identify those which are rich sources and ensure that you eat them in moderation only (see below).

Foods high in cholesterol

Beef, butter, chicken, turkey, duck, cream, all full-cream dairy products, fish, lamb , mutton, pork, tongue

Foods very high in cholesterol

Brains, caviar, egg yolks, giblets, kidneys, liver, prawns, shrimps

These foods are also high in saturated fat and should be eaten only occasionally. (Saturated fats raise blood cholesterol levels far more than does dietary cholesterol in animal foods.)

Overweight and heart disease

The role of obesity or overweight as an independent risk factor for CHD has not been clearly established, but what is known is that it is associated with risk factors such as raised LDL (`bad') cholesterol and total blood cholesterol, lower HDL (`good') cholesterol, hypertension(high blood pressure) and diabetes mellitus. Hypertension is much more common in overweight people; moreover, when weight is reduced and then maintained at a lower level, blood pressure tends to drop as well - if the weight goes up again, so does the blood pressure. There is a particularly strong link between obesity and hypertension in children and for this reason, it is important that children and adolescents do not gain excess weight - in fact, maintaining an ideal body weight should be a goal for the population in general.

Obesity also seems to be a significant, independent predictor of coronary heart disease, especially in women. Although women generally have lower blood cholesterol levels than men, these tend to rise after the menopause. Smoking also seems to be on the increase in women and this can be an important contributory factor. It has been shown that if you are overweight, a cigarette smoker and you take oral contraceptives, your risk of having a heart attack increases significantly.

In summary, the maintenance of ideal body weight by means of a combined diet and exercise programme makes good sense because of the relationship between obesity and an increased risk of heart disease. Also, for a large number of people who suffer from hypertension, weight control can be an effective way of treating the problem and may prevent the necessity for drug treatment.

What are the choices?

First let's look at the choices open to you, which also happen to reflect three different 'schools of thought' on the subject of diet and cancer:

The first choice is to carry on as before, on the grounds that there is still controversy over the extent to which diet is involved in cancer development, that the changes you would have to make are huge and unacceptable, that success is not guaranteed and that in any case there is a large element of individual susceptibility.

Next, there is the stance of the 'activists' who believe that the evidence available is very convincing, that major changes are needed and that they can be put into practice. If you take this approach, you will find a good deal of support in the marketplace, since food products with a low energy or fat content and/or which are high in fibre are becoming more readily available.

Many in this activist group take the holistic approach to avoiding disease, in other words, they believe that we should improve our diets so as to protect ourselves against all diet-related 'killers', not only cancer. Sir Richard Doll, a well-known British medical statistician, expressed this attitude in his 1982 Harveian Oration in London on 'Prospects for Prevention', when he urged:

'...whether the object is to avoid cancer, coronary heart disease, hypertension, diabetes, diverticulitis, duodenal ulcer or constipation ... the type of diet least likely to cause disease is one that provides a high proportion of calories in whole grain cereals, vegetables and fruit; provides most of its animal protein in fish and poultry; limits the intake of fats and if oils are to be used, gives preference to liquid vegetable oils; includes very little dairy produce, eggs and refined sugar; and is sufficiently restricted in amounts not to cause obesity'.

The third group recognizes the truth of the evidence put forward and accepts that dietary changes are required. But their view is that what is needed is simply to eat less and to practice moderation, even to the extent of cutting out alcohol and rich foods. This was the attitude taken by Hippocrates, Galen, Moses Maimonides and numerous other great physician-philosophers of the past.

The bottom line

Firstly, in spite of what might be regarded as a pessimistic tone to this chapter, it must be emphasised that what has been given here is an overview. The results of research may certainly give the experts good cause to be pessimistic - but remember that they deal in statistics. As in so many areas of life, if you as an individual are motivated enough to make the necessary changes, you can make the difference - to yourself and possibly to your family. In fact, considering the wealth of information now available, the prospect of taking individual avoiding action has never been better!

A diet which supplies 25% of energy from fat, and which contains 30g of fibre on a daily basis can certainly be formulated and could, with determined effort, become your personal norm. To do this you will probably have to eat far more of cereal products (which include whole grain breads, unrefined rice and breakfast cereals) and increase your vegetable and fruit intake considerably. You may also have to combat conservatism, inertia and lack of conviction and get used to a 'less palatable' diet - at least until you begin to enjoy foods that are closer to the way nature intended them to be!

It is important to realise that our eating habits are just that - habits - which we have learned and are capable of 'unlearning' if necessary. We don't come into the world craving over-refined breads, fried foods or creamy desserts; our tastes are developed from an early age in our own homes (which is why parents have a particularly important responsibility to guide the development of those tastes). A child who is regularly given white bread sandwiches and sweets for school lunches will probably always regard wholewheat bread and fresh fruit as hard work - yet getting into the habit of eating these and other unrefined foods will undoubtedly put him or her on a healthier nutritional path for life.

In conclusion, the take-home anti-cancer message could be reduced to simply this:

'Stop smoking; eat moderately; eat plenty of plant foods; and seek medical help early'.

Points to ponder

• Recently, there have been major reductions in the occurrence of a number of common diseases, including strokes and coronary heart disease. The full reasons are not known. Hence, it is conceivable that decreases could occur in some cancers, again for reasons not altogether understood. For example, there has already been a major fall in stomach cancer and in some childhood cancers.
• Individuals differ tremendously in their susceptibility to diseases. Obviously, if a parent had colon cancer, or a mother or sister had breast cancer, then the chances of getting such cancers are increased. However, because of differences in the ways people respond to cancer-producing substances, protection against the disease may not require too much avoiding action by a section of the community. This means that even partial reduction in the risk factors mentioned could put some people in a less vulnerable position.
• The dietary and non-dietary measures for the avoidance of cancer are exactly the same as those urged for the avoidance of coronary heart disease and other important diseases. So by following a low fat, high fibre diet you will in any case be protecting yourself against other 'killer' diseases.
• The field of alternative medicine may well produce some useful guidelines for fighting cancer in the future. Already the question is being asked: Are there 'non-orthodox' methods to prevent cancer, or to treat it, or even to cure it? Some interesting recommendations have been made, for example in the diets put forward by Kelley, by Gerson and by Forbes. These diets are largely or wholly vegetarian, with much of the plant food being eaten raw. There are encouraging case- histories which record the arrest and even regression of tumours, but none of the programmes described have been subjected to any form of controlled trial. At present enormous amounts of money are spent on trials in the treatment of various diseases, especially coronary heart disease. Perhaps some money should be devoted to investigating cases of possible 'alternative' cures for cancer. Even the validation of a small number of individual cases would be of great value, bearing in mind the formidable nature of the disease.