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!

Performance enhancement in perspective

There are countless nutritional products aimed at the sportsperson, which claim to have some performance-enhancing ability. These substances, called `ergogenic aids', theoretically improve performance to a point above that obtainable through a good training programme. Athletes are very susceptible to any claims for even the slightest improvement in performance, as fractions of a second could mean the difference between winning or losing.

Many ergogenic aids are basically expensive forms of proteins, minerals and vitamins. Their effectiveness is often unproven, based on folklore and reliant on the ignorance of the consumer (for example, substances such as Royal Jelly and wheat germ oil). On the other hand, some performance-enhancing principles are based on reputable scientific evidence that have been shown to improve performance in the laboratory (such as carbohydrate supercompensation - see overleaf).

However, it is interesting that even in cases where the supplement or _special diet has no physical basis, an athlete can sometimes gain purely psychological benefit from consuming something he or she believes in.

Proteins and amino acids

Although certain athletes may need an increased amount of protein, taking excessive amounts in the form of powdered or liquid supplements is unnecessary. Despite the claims of manufacturers, large quantities of protein will have no beneficial effects on muscle growth, strength or on performance. Any excess will simply be used as an energy source or stored as fat. In addition, kidney function may be hampered and dehydration caused as a result of taking in too much protein.

The supplements currently in vogue - especially among body builders and weight lifters - are amino acids, the 'building blocks' of proteins. The theory is that certain amino acids stimulate growth hormones. The increase however is slight and has no practical effect. Amino acids are not 'fat burners' or detoxifiers as has been claimed. Although tablets taken for this purpose are extremely expensive, the amount of amino acids in them is very small. In fact, a single egg contains far more than that found in seven or more amino acid tablets!

Vitamins and minerals

As mentioned earlier in this chapter, supplementing vitamins and minerals has no performance-enhancing properties in an athlete whose normal diet is not deficient. The effects of taking megadoses of certain vitamins may even impair performance.

Manufacturers and quasi-nutritionists have given certain substances vitamin status, although they are not scientifically classified as vitamins. For example, pangamic acid (otherwise known as vitamin B15) supposedly prevents various diseases, slows the ageing process and improves physical performance. None of these claims has been substantiated. Laetrile or vitamin B17 is a source of cyanide and has been banned. Other `pseudovitamins' are orotic acid (vitamin B13), bioflavenoids and vitamin B-T (or carnitine), all of which do not function as vitamins.

Carbohydrate loading

`Carbo-loading' is a phrase which has passed into common use. It has been proved scientifically that carbohydrate loading (otherwise known as carbohydrate supercompensation) is one of the practices which is effective in improving performance. It may be explained in the following way: Exercise which lasts for longer than 60-90 minutes is dependent on the amount of glucose available. Glycogen (glucose) stores in the muscle and liver are small, so enlarging them allows an athlete to continue exercising at a higher intensity for longer. A carbohydrate-loading programme increases the amount of muscle glycogen stored before you need to use it.

The best method of doing this is to gradually reduce the amount of training you do during the six days preceding an event and, during the final three days, eat a diet that is high in carbohydrate (500-600 grams per day). The extra glycogen stored in this way allows the athlete to continue exercising for longer.

Carbohydrates, fluids and sodium during exercise

It has been proved that supplying the body with carbohydrate during endurance-type exercise has a glycogen sparing effect which allows an athlete to exercise for longer. Many studies have been done in attempts to find a solution that will allow the maximum amount of water to be absorbed, while at the same time providing an optimal amount of carbohydrate. So far, it seems that a form of carbohydrate known as 'glucose polymers' has the best absorption rate. These are chains of glucose molecules linked together. A solution containing about 10 per cent carbohydrate in the form of glucose polymers supplies the most glucose to the body during exercise, and at the same time provides sufficient water replacement. (It is important to remember that a carbohydrate solution is only of benefit during prolonged exercise.)

Adding sodium to replacement fluids increases the concentration of the fluid. It was initially thought that this would hamper the absorption of the fluid, but the most recent findings suggest that the addition of a very small amount of salt (1-2 grams per litre) is in fact necessary for absorption.

Alcohol

Not surprisingly, it has been proved that alcohol has no beneficial effect on exercise. In reality alcohol is a depressant that slows reaction time, impairs muscle reflexes and disturbs coordination. In addition, it causes dehydration which interferes with fluid balance and has a negative effect on performance.

Caffeine

Some athletes use caffeine as a stimulant and to increase the amount of free fatty acids in the blood. Theoretically, more fat is then available to be used for energy, resulting in glycogen sparing (see above). However, an excessive amount of caffeine is necessary to produce this effect and, apart from the fact that a very high concentration of it in the urine can disqualify a competitive athlete, there are several other disadvantages to using caffeine in this way. The main one is that it has a diuretic effect, which results in increased fluid losses and a greater risk of dehydration. In addition, overconsumption of caffeine can result in headaches and nausea and it is therefore not advisable to use large doses of this stimulant in an attempt to enhance performance.

Other imposters

Royal jelly, wheat germ oil, ginseng, extracts of various herbs and numerous other products have all at one time or another been touted as performance-enhancers. The truth is, however, that the only possible effect most of these substances could have would be a psychological one.

Cancer – Can Your Diet Make the Difference?

Firstly, can it really be said with confidence that if you eat much less, or much more, of a particular foodstuff - or combination of foodstuffs - you will become immune or less at risk to this or that cancer? To begin with, it has been proved beyond doubt that cancer can be prevented in experimental animals through dietary changes. In particular, reduced energy (kilojoule) and fat intakes and increased consumption of fibre- rich foods and certain vitamins have been found to inhibit the development of cancer. The question is, can these findings be appliedto human beings?

Here there are two very important questions: Firstly, to what extent is there a link between human diet and cancer, and secondly, how drastic are the changes we have to make to our eating patterns in order to bring about a significant drop in cancer development?

The first question is possibly easier to answer than the second. Researchers are now convinced that, in dietary terms, humans share the same cancer risks as animals. Simply put, these are:

• eating too much food in general and too much fat in particular
• not eating enough of the fibre contained in grains, legumes (beans, peas, lentils), fruit and vegetables
• low intakes of certain vitamins

The fat, vitamin and fibre factors

A high fat intake leads to a high concentration of faecal bile acids which can, under certain circumstances, act as carcinogens (cancer- producing substances). A low fibre intake results in a high faecal pH value, which favours the development of carcinogens; it also causes waste to take longer to move through the bowel, allowing time for cancer-causing substances to develop and take effect. On the other hand, a low intake of certain vitamins has a negative effect on the mechanisms which combat damaging reactions in the body's cells.

High fat diets - especially those high in saturated fats - have been linked to cancers of the breast, prostate and colon-rectum and low fibre diets to the latter in particular. A diet low in vitamin C is associated with gastric cancer, while one that is deficient in vitamin A seems to create favourable conditions for prostate cancer; a lack of vitamin D is linked to cancer of the colon. The mechanisms involved in all these processes are far from clear and much research still has to be done. (See also The Cabbage Patch Diet on page 187.)

The challenge to change

Authorities on cancer such as the US National Cancer Institute, the 1988 US Surgeon-General's Report and the 1989 Report of the UK COMA (Committee on Medical Aspects of Food Policy) have laid down guidelines for dietary changes which they regard as vital in the fight against cancer. Firstly, they maintain that fat should supply only 25-30% - instead of the present 40⁰/a - of our total food intake. In effect, this reduction by a third or so would bring our fat consumption to the level of the poorest people in the big cities in the 1920s! No fall in fat intake has occurred recently in Western populations.

For a marked fall, there would have to be a big increase in the intake of carbohydrate, or starchy, foods. But as mentioned above, our bread consumption is low - 120-150g or 3 to 4 slices daily - and possibly decreasing. Why has it fallen? Firstly, there has been a marked increase in the consumption of more 'palatable' foods such as dairy produce, meat, fish and eggs and secondly, the modern era's obsession with slimness has led to the (erroneous) belief that bread is specially fattening. It is invariably one of the first foods to be restricted or cut out totally in any attempts at weight loss.

In practical terms, to reduce our fat intake to the recommended levels, the average person would have to eat a good 50% less of all visible fat - butter, margarine, spreads and obvious fat on meat - than at present. The realization that changes in this area must be large, not trivial, has been underlined by recent studies which show that in the case of breast cancer, only a very low fat intake which supplies as little as 25% of energy (50-60g fat daily), is likely to give protection.

What about fibre? The experts recommend that it be increased from the present 10-15g to 25-30g or more daily, through a higher consumption of fibre-containing foods, cereal products (wholewheat bread, brown rice and unrefined breakfast cereals), legumes, vegetables and fruit. This means adopting a diet similar to that of strict vegetarians. In the USA, surveys show that only half of the population eat one serving of fruit and one serving of 'garden' vegetables on any one day - yet four or five helpings arerecommended. The fact of the matter is that in most countries, there have been no significant increases in the amounts of plant foods eaten daily.

The picture is much the same when it comes to intakes of vitamins and mineral salts. Admittedly, pill manufacturers are doing a roaring trade, but as any doctor will tell you, that is not the way to get your vitamins. Nature has provided us with an abundance of fruit and vegetables which, apart from being excellent sources of vitamins and fibre, are a good deal lighter on the pocket than the packaged variety. In addition, some vegetables have been found to be particularly effective in fighting diet-related cancers because of their high concentrations of certain vitamins.

Food allergy or food intolerance?

There are at least five reasons why some people are unable to tolerate certain foods, of which allergy is only one (see below). In true food allergy the body's immune system is directly involved, whereas in food intolerance other factors play a role. The manifestations of the reaction - such as sudden vomiting or diarrhoea - may be identical in both cases.

The most obvious example of food intolerance is simple toxicity. Contaminants - substances which get into food during the growth, harvesting, processing, packaging or storage of food - are occasionally harmful. In severe cases these incidental additives can make foods poisonous and anyone eating them will suffer ill effects.

Much less obvious are the adverse reactions of a few people who lack the enzymes necessary to digest certain foods. A common example is lactose intolerance. A significant number of people come into the world without the enzyme lactase, which is essential for the digestion of the milk sugar lactose. As a result, they invariably suffer from flatulence and diarrhoea when they drink cow's milk. The majority of the population obviously have the necessary enzyme and can drink milk without any ill effects.

A third - and very interesting - possible cause of intolerance is our psychological reactions to foods. It has been shown that if you are convinced, because of a past experience, that you have a bad reactionto a certain food, you will usually avoid it. But if you do eat it again the chances are it will affect you in the same way, sometimes eventhough it cannot be proved that you are in any way allergic to it. One survey of 580 adults found that two-thirds of them avoided one ormore foods because of their taste or texture or due to some past reaction.

Next come foods that produce reactions which seem very much like true allergic responses. For example, mature cheese may contain histamine or tyramine (which will cause reactions) while foods such as strawberries and shellfish may trigger off certain cells in the body which are directly involved in allergic reactions. These are not true allergic reactions because they do not involve the immune system and naturally occurring chemicals within the foods - not the foods themselves - are responsible for triggering off the reactions.

So much for food intolerance. What we are really referring to when we talk about 'food allergy' are those reactions which have a truly allergic basis and have to do with the body's immune (defence) system.

Potential problem foods

The following are some of the foods which most commonly cause reactions in sensitive individuals:

Foods rich in histamine: Cheese, chocolate, avocados, bananas, tomatoes, sauerkraut, broad beans, canned figs, soy sauce, meat and yeast extracts, smoked or pickled fish, liver, alcoholic beverages (except whisky, gin and vodka).

Foods rich in tyramine: French cheeses such as Camembert, Brie, Gruyere and Roquefort; Cheddar cheese, brewer's yeast, herrings, chianti.