Nutrition-Related Cancer

Introduction

World-wide epidemiological studies carried out in the past two decades suggest that up to 80% of human cancers, in particular bowel cancer, stomach cancer, breast cancer and head and neck cancer, are induced by what we eat and drink. Cancer of the prostate and of the pancreas are also affected by dietary factors, but to a much lesser extent.

The Large Bowel

Cancer of the large bowel is found mostly in affluent, highly-developed countries and it is much more common in urban areas than in rural, sparsely populated districts in those countries. Furthermore, there seems to be a direct link between the consumption of meat and the frequency of bowel cancer. This disease is virtually unknown in Tibet and Thailand, where practically no meat is consumed. It occurs with moderate frequency in Japan and Chile, where modest amounts of meat are consumed, but the highest incidence of bowel cancer occurs in Scotland, Canada, New Zealand, Australia and the USA, which are countries with the largest meat consumption.

In 1985 130,000 cases of bowel and rectum cancer were diagnosed in the US, of which 65,000 died. A further piece of conclusive evidence about the link between diet and bowel cancer is provided by the US black population. American blacks have shown a dramatic increase in bowel cancer following the introduction of the Bill of Rights and their resulting affluence. This has raised their standard of living and has enabled them to copy the diet of whites, including daily consumption of large amounts of meat. The extremely high bowel cancer rate in American Negroes stands in marked contrast to Negroes in Africa, among whom bowel cancer is virtually unknown.

Evidence to show lower incidence of bowel cancer because of a higher consumption of cereals, fruit and vegetables in their diet, is provided by US Mormons and Seventh Day Adventists in California. Similar evidence also comes from other parts of the world. For instance, in India, the Parsees who eat a Western-style diet suffer from bowel cancer much more frequently than the general Hindu population.

Further very convincing evidence is provided by Japanese migrants who have settled in Hawaii or California and who, on adopting a Western-style diet, including large beef consumption, have shown a parallel rise in cancer of the large bowel after one generation.

What, therefore, has been shown by these studies is that it is not only high meat consumption but a diet low in vegetables, particularly cabbage, broccoli and Brussel sprouts, which appears to increase the likelihood of developing cancer of the colon.

Similarly, a high-fibre diet seems to have a protective effect as shown by the low incidence of bowel cancer in rural Africans, as well as in Israelis of Asian or African origin who eat fibre-rich food.

Summary

World-wide studies have confirmed conclusively that a diet high in total fat and high in red meat, especially when it is also low in fibre, vegetables and the mineral selenium (p. 85), is associated with a significantly increased incidence of large-bowel cancer. The disease eventually develops in approximately 6 per cent of the American population, and six million Americans who are alive today will die of it.

The Stomach

Cancer of the stomach is known to occur more frequently in lower class Western males around the age of 55 years. The incidence of stomach cancer can be lowered by eating Western-type vegetables, such as lettuce, tomatoes, celery and corn, whereas eating Japanese-style salted, seasoned, spiced or cured food tends to raise the frequency of stomach cancer.

Nitrites and nitrates are chemical substances containing nitrogen which are present in human saliva. These substances have been shown to cause stomach cancer in experiments on animals. Their role in human cancer is a complex one, but they do not appear to increase the risk of stomach cancer in people, particularly when they are eaten together with fruit, vegetables and salads. It is thought that they are neutralised by the high Vitamin C content of these foods. This is one reason why fresh vegetables and fruit should be eaten throughout the year, rather than seasonally. It is worth repeating that a reduced salt intake is beneficial as regards avoiding stomach cancer.

The Breast

Convincing epidemiological evidence is available to show that diet is one of the many contributory factors to breast cancer. In Western countries the incidence of breast cancer continues to rise after the menopause, whereas it remains the same in Japan. This difference is believed to be due to dietary practices in the high-risk countries of the West. This belief is reinforced by the increased incidence over the past 40 years of breast cancer in American blacks. This again is thought to be due to eating more of the rich food now available to them as the result of their improved earning capacity.

Similarly, the latter-day increase of breast cancer in Japanese women is thought to be related to the recent shift of the Japanese to a more Western-style diet with a particular increase in fat consumption. This is known to affect the hormones associated with breast tissue.

The Oesophagus

Alcohol and tobacco are known to interact and reinforce each other’s detrimental effect in the production of cancer. Too much of both increases the risk proneness to oesophageal cancer. There are a number of oesophageal-cancer ‘hot-spots’ in Western Europe, North America and the wheat-eating (as opposed to the rice-eating) parts of China.

When alcohol intake is excessive it can destroy hunger, seriously depress appetite and interfere with absorption of nutrients, vitamins and minerals. This can lead to an unbalanced diet and nutritional deficiencies which give rise to cancer.

The Pancreas

High fat consumption and over-eating are associated with an increased incidence of cancer of the pancreas. It is this excessively rich type of diet which has been linked with the climbing rates of pancreatic cancer in the West, particularly among American Jews who eat food much richer in fat than Jews of Asian or African origin. Dietary fats are thought to create carcinogens in the bile and cause it to flow back into the pancreas.

The Prostate

There is a marked difference, both geographic and racial, between Western countries (including the USA and Britain) where prostatic cancer is common, and Japan and Africa where it is rare, as well as between the US black and white population, where the incidence is greater among blacks. Yet African blacks have a much lower incidence than even American whites, which suggests that environment affects American blacks. An important factor appears to be population density, as there are fewer deaths from prostatic carcinoma in sparsely populated areas in the USA. When prostates in men who have died from other conditions are examined through a microscope, unsuspected cancer is found in about 45 per cent of all men over the age of 50, but it is only in affluent societies that they seem to develop into active malignant lesions. This is probably caused by increased hormone production, resulting from over eating.

There is an interesting scientific relationship parallel between the incidence of prostatic cancer and that of breast and colon cancer. When comparing the high- and low-risk areas in the world, the one striking difference was found to be the intake of fat. In the high-risk areas the intake is double (40 per cent of the total calorie intake) that of the low risk regions (20 per cent of the total calorie intake). When comparing geographic areas in the United States in relation to their whole-milk and beef consumption (as a measure of the fat-intake of the respective populations) it is found that the north-central and mid-west areas, with the highest fat consumption also have the highest prostatic-cancer mortality rate.

Like breast cancer, prostatic cancer is hormone-dependent and any factor, such as diet, affecting hormonal secretion, also influences the frequency of prostatic cancer. It is interesting to note that, in fact, a vegetarian diet was found to lower the prostatic cancer rate, possibly because of a decreased overnight release of such hormones as testosterone.

Our Daily Bread

Our life expectancy is longer now than it was 200 years ago. It is longer, not because we are healthier but because of our greatly improved public health measures, in particular:

• vaccination against smallpox, tetanus, whooping cough, diphtheria and infantile paralysis
• sterilisation of water supplies
• compulsory pasteurisation of all milk.

In fact our health is worse and this is due, to a large extent, to our food which is richer, softer and sweeter than ever before. It is richer because we eat more fat; it is softer because it is processed and refined to a high degree and has lost its natural fibre content (together with other nutrients) and it is sweeter because our greatly increased consumption of sugar makes us prefer sweet foods, which manufacturers are very happy to supply.

We already know what eating habits cause cancer and so must realise that by changing these eating habits we could avoid cancer and that the choice is ours, even if we decide to do nothing about it. Just as we assume (wrongly) that it is normal for old people to lose their mobility and energy, to suffer from rheumatism, arthritis and chestiness, to become overweight and lose some of their mental alertness, so we accept (again wrongly) cancer and heart disease to be part of our normal lives today; they certainly are not normal and the evidence that they need not be is clear.

There are about 40 substances that we should eat for good health, but no longer do; instead we fill ourselves with refined, high-calorie food, rich in fat and sugar and, as a result of feeling full, leave out certain food items which the body cannot do without. Too few of us realise that eating what we like and eating healthily are compatible and that as food and health are so closely related, our choice of food also decides our state of health.

There are two main reasons for eating: firstly we provide the body with nutrients for tissue growth and repair; and secondly, we eat for fun, which is obviously the more pleasurable one of the two, although rarely healthy.

Since it is food we eat, not nutrients, we need to find out which of the three main types of food (proteins, fats and carbohydrates) are most required for good health.

Proteins

Proteins are the main body-building and repair foods. The most concentrated sources are found in meat, fish, cheese, milk, eggs, nuts and soya beans. Other, smaller sources of protein are wheat and pulses. The total daily protein requirement is only 45g ((fl. oz.) and should represent no more than 10 per cent of our daily food intake.

Fats

Fats give long-term energy because they take longer to be digested and absorbed into the system. They are found in foods as visible fats like lard, suet, cooking fat, oil, butter, margarine, cream and fat on meat, and as invisible fats in milk, fatty meat, cheese and oily fish. Small quantities are even contained in cereals. Vegetables and fruit, apart from avocado pears and olives, contain a very small amount of fat. When chemically analysed, fats contain, as part of their make-up, substances known as fatty acids. These come in three types:

Saturated Fatty Acids

These are found mostly in foods of mainly animal origin. Over long periods, eating too much food containing saturated fatty acids tends to increase the blood cholesterol level. These fats are found in cream, cheese, milk fat, butter, meat fat, cooking fat, dripping, lard, suet, coconut and palm oils, cocoa and chocolate, and in hard and soft margarines which are not specifically polyunsaturated.

Mono-unsaturated Fatty Acids

These fats neither raise nor lower blood cholesterol levels. However, they do add to the total daily fat (and energy) intake, and foods containing them also have some saturated fatty acids as well. They are found in largest amounts in olive oil, peanut oil, olives, and avocado pears.

Polyunsaturated Fatty Acids

These tend to lower blood cholesterol levels. They are found in safflower, sunflower, corn and soya-bean oil. Polyunsaturated margarines are a convenient source of this type of fatty acid. However, even the highest polyunsaturated fats are only 72 per cent poly, the rest being mono and saturated fat.

Essential Fatty Acids

Three fats are referred to collectively as Vitamin F. Although required in only very small amounts, they are nevertheless essential to health (that is why they are called essential fatty acids or EFA). They must be supplied in such foods as milk, cheese, eggs, nuts, sunflower or corn oil, linseed or wheatgerm.

The total daily fat allowance should be below 20 per cent (not as at present, over 40 per cent) of the daily food intake, that is less than 50g ((fl. oz.).). For instance, butter is pure fat, as is margarine. Cheese is equally unhealthy, because it is concentrated fat. If women, in particular, continue eating it in anything but small amounts they might just as well spread it on their thighs, because sooner or later that is where it will surely end up! Low-fat cheese is better, but no cheese is best. Other whole-cream milk products should also be struck off one’s shopping list. In fact, anything with the word cream in it is better omitted: cream cheese, whipped cream, ice cream, cream soup, sour cream and so on. If we substitute the word fat for cream and call them fat cheese, whipped fat, ice fat, fat soup or sour fat, because that is what they all are, it may be easier to give them up. Mayonnaise is also bad; it is full of fat and salt; one tablespoon has the calories contained in two tablespoons of white sugar. On the other hand, low-fat yoghurt is a wonderful substitute for sour cream, for instance in a baked potato.

Cholesterol

Cholesterol is a fat which is found in the blood. It is one of the main factors contributing to heart disease and as a fat also represents a cancer risk. It is manufactured in the body but it is also supplied in food; there are four food-groups:

• Cholesterol-free: all plants, vegetables and their products.
• Low cholesterol: skimmed milk and low-fat yoghurt.
• Medium cholesterol: fish, lean meats, whole milk and cheese.
• High cholesterol: all offal (such as heart, liver, brain, sweetbread), roes, shrimps, prawns, Stilton, Cheddar and egg yolk.

Red meat also contains a lot of hidden fat; veal is leaner; skinless chicken is better but fish is even healthier; like cheese, meat is best left out altogether. This also goes for fried food. Grill, steam, boil or bake instead.

Carbohydrates

There are two groups of carbohydrates. Natural, also called complex, carbohydrates are known as the ‘good guys’. The simple processed or refined carbohydrates like white sugar are the bad guys’, and contain sugar in the form of sucrose.

The natural carbohydrates are fruit, vegetables and whole grain products such as bread, cereals, flour, potatoes, rice, maize and pasta. They convert slowly into blood sugar and supply us with vitamins, minerals and roughage; they are the desirable ones.

The bad guys’, those in soft drinks, colas, white bread, and sugary cereals are empty calories with little nutritional value. They are rapidly converted into glucose in the blood; they cause sugar imbalances, they exhaust the pancreas and can eventually lead to diabetes. They include all forms of sugar, whether white, brown, raw, or Demerara, glucose, syrup, treacle, molasses, jam and marmalades and also honey (which contains fructose not sucrose). Fructose is also found naturally in all fruits and in this form is easier to digest without putting a strain on the pancreas.

Obesity

Obesity is a pre-cancerous stage. Avoid obesity and you can avoid cancer. There is a direct link between opulence, overweight and the cancers of affluence.

Fats and sugar are the two ‘high-calorie risk’ food components in any diet; they are needed by the body solely as a source of energy for heavy physical work and for athletic pursuits. In the absence of such physical activities, too much fat and/or sugar taken regularly will inevitably lead to fat storage and weight gain. Fat has the highest calorie content per volume and eating butter and margarine, or constantly frying foods in cooking fats or oil, will greatly increase calorie consumption.

Each ¼lb (120g) packet of butter or margarine provides over 1,000 calories. Fat forms at least 40 per cent of the total calorie content of cakes, biscuits, pastries, puddings, potato crisps, peanuts, chocolate and chocolate-covered sweets, sauces, cream soups, salad cream, sausages, mayonnaise, beef burgers, most meats, all fried food, cream, eggs, whole milk and cheese.

Of the carbohydrates consumed, one-third is taken as sugar and half of this is used in tea or coffee and the rest in manufactured and cooked foods. Sugar should be reduced to the status of a condiment, not only on account of its calorie content but because together with fibre deficiency, it alters the dominant type of colon bacteria, thus increasing the risk of cancer of colon and rectum.

Drinking a total of five cups of either tea or coffee a day, with two teaspoons of sugar in each cup, gives 225 empty calories; most people throw away 10 per cent of their daily calorie intake on non-food. Similarly, alcohol provides no nutrition - only calories. A percentage of these surplus calories, not needed to fuel the body with energy, is then stored as body fat and this is what makes people overweight.

To lose weight, the amount of dietary fat and sugar taken must be reduced. Reduction of the complex carbohydrates is not a good thing because fibre-rich starchy foods are an essential part of a complete, balanced, healthy diet. Most people are, or at least should be, aware that short-term rapid weight loss with rigorous diets depends on loss of body water (with glycogen and protein) not body fat. It takes months for many overweight people to lose the actual excess fat. A weight reduction of 21b ((1kg) per week is the maximum loss desirable for the majority of adults. After weight loss, the energy intake should be permanently adjusted in order to avoid regaining weight; this can be achieved by increasing consumption of wholemeal bread and wholegrain cereals (high-fibre content), vegetables and fruit. Food rich in fat (meat products and fried food) and those rich in sugar have to be restricted on a long-term basis.

Behavioural Slimming

Behaviour slimming is based on the idea that overweight people wishing to slim need first to be told how to recognise what causes their current bad habits. Then they must be shown how to invent methods to overcome these problems and so establish new, better patterns of behaviour. Few obese people are aware, for example, that they eat a great part of their food while walking about the house doing other tasks. They need to become conscious of this so that they can regulate their eating pattern. Those who wish to slim should have meals in a setting where they can appreciate that they have had a meal, without other distractions. In this way snacks between meals can be avoided, because the routine for meals has to be followed at all times. Many people eat more when they are bored, tired or under stress, so slimmers should pay special attention to their eating habits at these times. A considerable effort is demanded of the slimmer and success depends on his or her dedication. Adopting the 'restricted foods' type of diets is undesirable for healthy people though they may be necessary for patients with allergies or other abnormalities. The most effective and painless way to lose weight is first to choose an ideal weight for the rest of one's life, then to try and reduce one's diet by 200 calories a day, through a mixed diet of skimmed milk, whole-wheat grain, vegetables, poultry, fish, fruit and the occasional egg - a diet which ensures an adequate amount of all vitamins and minerals. If, additionally, another 300 calories a day can be lost in physical activity (an hour's brisk walking), this will lead to a total daily reduction of 500 calories and will result in a weekly loss of 500g (one pound) of fat. Since it takes months to gain weight it cannot, despite claims to the contrary, be lost in a few days. The only solution is to learn new eating habits and to keep them for life. Perhaps the best rule of all to help achieve this is always: 'eat little of everything and nor too much of anything' In health, as in all other worthwhile pursuits, quick short-cuts actually never stand a chance. Yet, since hope springs eternal in the human breast and since people are even more gullible than usual when it comes to health or slimming, they will be only too willing to believe what they read about instant loss of weight and will try to buy hope, as if they were in a betting shop or on the stock exchange. Inevitably they will lose because, as with the other areas of our lives, most great achievements have to be earned the hard way.

Micronutrients (Vitamins and Minerals)

Vitamins

Most people have an adequate vitamin intake in their diet, sufficient to ensure good health, yet in the UK the annual over-the-counter-sales of packaged vitamins is estimated at over £45 million. Similar figures are found in other parts of the Western world too. Although vitamin supplements are rarely needed for normal adults, they should be considered for: - people who rarely go into the sunlight -- people with a restrictive diet, such as vegetarians and other food faddists - people with a poor intake, such as anorexics, depressives and alcoholics - people of advanced years - people, such as commercial travellers, who regularly eat in canteens and low-price cafes - people who live on packaged and 'fast' junk food - convalescents, expectant nursing mothers, infants, young children and adolescents. Here are some concentrated sources of the five principal vitamins: Vitamin A: liver, carrots, apricots, spinach and cheddar cheese Vitamin B (complex): brewer's yeast, unpolished rice, wheatgerm, whole grains, liver, cheese, fish, yoghurt, nuts, pulses. The essential Vitamin BY is required in tracer doses. Except for yeast and seaweed it exists almost exclusively in foods of animal origin such as liver, most meats, milk, eggs and cheese. For this reason vegetarians may experience deficiency. Vitamin C: rose hip, fresh citrus fruits, cabbage, red and green peppers, fresh green leaf vegetables, strawberries and watercress. Nobel-prize Laureate Dr Linus Pauling recommends high doses to maintain the immunological defence system. Vitamin D: milk, cheese, cod liver oil, herrings. Vitamin E: wheat germ, whole wheat, almonds, peanuts.

Minerals

All minerals essential for health are plentiful in a mixed diet and mineral deficiency, therefore, is rare. For example, in a well-balanced diet, calcium is found in milk and cheeses, phosphorus in all meat products and eggs, magnesium in bran and nuts, iron in red meat, liver, black treacle and baked beans and zinc in meat, offal and shellfish.

One of the main functions of minerals is to keep a perfect balance between many of the acid and alkaline elements in the body. Sodium, potassium, calcium, magnesium, manganese, iron and copper are alkaline and iodine, phosphorus, chloride and sulphur are of an acid producing nature, thus preventing an alkaline excess. Sodium probably plays the most important role in keeping a perfect balance between the acid and alkaline elements in the body. The desirable daily intake of sodium, usually in the form of ordinary salt (sodium chloride), should not exceed a quarter of a teaspoon (one teaspoon has more than 2 grams). There is nothing good about adding sodium to our foods, because it is already in almost everything we eat in larger quantities than we need; there is salt in mayonnaise, cottage cheese, soya sauce, tomato sauce and a long list of other foods.

Free Radicals

A free radical (sometimes also called an oxygen radical) is an atom or a group of atoms with an uneven electrical charge, meaning that these atoms have acquired one surplus electron as a result of oxidation and become extra-reactive and determined to combine with something else. Inside the body this something else is usually the DNA (the cell’s genetic blueprint) from which, in order to complete themselves, the radicals steal an extra electron; this can set up a chain reaction during which more free radicals are produced. These are then available to damage more cells, thereby interfering with normal cell production and initiating a mutation - a change of chemistry and function - as a result of which the cells will start dividing abnormally, in an uncontrollable manner, which may ultimately culminate in a cancerous growth. If the oxidative process can be prevented there will be no atoms with surplus electrons and so no mutation.

Free radicals are formed by many normal reactions, such as the presence of oxygen peroxide, or the inhaling of oxygen. For example, unsaturated oils such as vegetable oils, which are particularly susceptible to free radical damage become rancid, especially when heated.

The body defends itself against free radicals by using the small molecules that protect cellular DNA from oxidative damage. The most important among these are the three vitamins: A, C and E. The reason, for example, that Vitamin A in carrots, and carotene-containing yellow, red and green vegetables, provides effective protection against lung cancer in smokers, may be related to the high level of oxidants in both cigarette-smoke and tar, and how these are attacked by the carotene.

Selenium

Alternatively, there are enzymes designed to disarm free radicals. One such antioxidant enzyme is called glutathione peroxidase (GP). its effective action depends on the mineral selenium. When the dietary intake of selenium is increased by a factor of ten the activity of GP will be doubled. In a number of studies it was found that people with a very low selenium level had a greater chance of getting cancer than those with a very high level. Similarly, breast cancer rates in selenium-rich parts of the world are unusually low.

Too little dietary selenium is associated with an increased risk of fatal cancer. What is more, low Vitamin E intake may enhance this effect. Selenium is abundant in meats, seafood, yeast, eggs, liver, kidney, garlic, onions and mushrooms. It is absent from refined foods, but ample supplies always exist in a balanced mixed diet. An adequate daily dose is 300 micrograms.

Uric Acid

Another antioxidant is uric acid. its high blood concentration can be further increased by consumption of dietary purins, but too much can cause gout. Foods high in purins are sweet-breads, anchovies, sardines, shrimps, mackerel, liver, kidney, meat extracts and dried legumes. (In smokers a low uric acid concentration may represent a contributory factor to lung cancer.)

Summary

Vitamin A, Vitamin C, Vitamin E, selenium and uric acid have been shown to be the most important anti-carcinogenic protective factors in our diet. Of these only selenium and uric acid are toxic in too high concentrations:

Other Minerals

Nitrates

A great deal has been written about the danger from nitrites and nitrates used against the deadly botulism in the preparation of bacon and the curing of various meats, because in the body they combine with amines to produce nitrosamines, which are known to be strong carcinogens in most animals. Of course, traces of nitrosamines are found in both bacon and some processed meats but traces are also found in most vegetables such as spinach, radishes, celery, lettuce and turnips. In any case, nitrites are also found in human saliva and it is therefore not surprising that there is no evidence that in humans nitrite-treated foods are carcinogenic.

Cyclamates

As regards cyclamates, even in animals, more recent repeat-tests have failed to confirm the development of bladder tumours, following the original scare in the USA in 1969, when eight out of 240 rats on very high doses of cyclamates developed what appeared to be bladder tumours, four of which were subsequently confirmed as carcinomas.

Saccharin

Similarly, saccharin appears to be quite safe. It has been in use for 81 years and although three out of 100 rats fed huge amounts of saccharin developed bladder tumours when the experiment was first carried out in Canada in 1977 (resulting in the banning of saccharin in Canada), the results of these experiments have not since been confirmed by other experiments.

In any case, most epidemiological studies in humans since 1977 have failed to show any relationship between taking saccharin and bladder cancer. Significantly, diabetics have a lower bladder cancer incidence than that found in the rest of the population, possibly also because diabetics smoke less heavily than average.

There is, therefore, no evidence that artificial sweeteners such as cyclamates and saccharin cause cancer in man, and they should both be considered safe.

Cooking

During cooking, the outside of food can be burnt, for instance on charcoal grilling of steaks at barbecues, or when carbohydrates are caramelised, as on the brown-crust of toasted bread. These burnt or caramelised surfaces contain a large variety of DNA-damaging agents, which are presumptive carcinogens, known to produce cancer in animals. Good cooks do not usually burn much of the food they are cooking, but they do caramelise it.

The total amount of such burnt material consumed may be as much as several grams, a menacingly large amount when compared with a mere half-gram of burnt material inhaled in a single day by a person smoking 20 cigarettes, and who as a direct result, can expect a shortening of his or her life expectancy by an average of eight years.

Cooking also makes the oil and fat in meat go rancid and this increases the number of oxygen radicals and hence of presumptive carcinogens. Protecting ourselves against these large numbers of oxygen radicals should be a most important step in our campaign to avoid cancer. We can do this by increasing our consumption of uncooked food, avoiding burnt or caramelised food and by taking plenty of Vitamin E, Vitamin C, beta-carotene, selenium and uric acid.

Coffee

One cup of coffee contains 100 milligrams of caffeine which at one time was thought capable of inhibiting DNA repair thereby increasing the likelihood of tumour formation following a mutation. Recently, as a result of a survey of 14,000 coffee drinkers who had been observed for 17 years, coffee has been cleared of this suspicion. Scientists could find no association between coffee and cancer, despite a US survey three years ago that prompted researchers to suggest that it might cause cancer of the pancreas. These findings have been hotly disputed ever since. It is thought that the answer to the relationship between cancer of the pancreas and increased coffee consumption reported by the US scientists has been misinterpreted; it is now suggested that it is the condition itself which may cause the sufferers to drink more of everything, including coffee, due to the body’s disturbed glucose tolerance. It is thought that this factor, which would directly affect the amount of coffee consumed, was not taken into account by the US researchers. (Yudkin et al., Lancet February 1984.) On the other hand, it should not be forgotten that browning and burning organic substances such as roasting coffee beans, produces substances which can damage DNA or inhibit its repair faculties. Several such substances have been isolated so it is a good idea to refrain from drinking too many cups of coffee a day. Besides, frequent cups of coffee or tea make people over-tensed and unable to relax properly, this contributing to stress instead of, as intended, relieving it.

Tea and coffee act both as a drug and a stimulant; as a drug they are habit forming, as a stimulant they are nutritional stressors causing increased general irritability.

Their stimulating effect is due to the caffeine (or theine) they contain. They are refreshing, because they are served hot and because, in our minds, we associate them with comfort and sympathy.

Dietary Fibre

Dietary fibre is the medical term for roughage ~ food; it is the scaffolding that supports plants, giving them their shape and strength. Modern research has shown that as well as preventing constipation it has many other beneficial effects yet it is removed by modern food processing to our great loss. Most fibre is a mixture of substances which passes through our digestive system more or less unchanged and unabsorbed.

It was Dr Denis Burkitt who said that dietary fibre, and in particular bran, might be important in the prevention of bowel cancer. Bran is the husk, or outer shell, of the wheat grain, and is not used by human digestive enzymes. In whole-wheat there are two types of fibre: crude fibre and dietary fibre (which is finer and about five times as plentiful). It contains complex carbohydrates such as lignin which passes through the bowel totally unchanged, cellulose, hexose and pentose polymers. Pentose polymers are abundant in cereal fibre, present to a lesser extent in other vegetables, but do not occur in potatoes and are thought to produce soft, bulky stools. It is probable that the cancer-reducing effect of fibre is due to the reduced time that the soft bulky stools remain in the bowel. Also, this cancer-reducing effect is increased by altering the total number and proportions of different types of bacteria in the bowel, some of which are capable of destroying carcinogenic metabolites. Furthermore, the presence of phytic acid in bran inhibits the iron mediated formation of the free oxygen radicals. In this way colonic carcinogenesis can be suppressed by bran and other diets rich in iron binding phytic acid.

These findings are confirmed by reports from Scandinavia where there is close correlation between bulky stools containing pentose polymer and phytic acid and low large-bowel cancer. This is the case in rural Finland where diets include large amounts of unrefined rye bread; the stools are bulky and the incidence of large-bowel cancer low. The opposite is true in Copenhagen, where the chief difference from the Finnish diet seems to be a much smaller consumption of unrefined cereals.

Because of its vital importance to health, it is worth repeating that eating vegetables, fruit and high-fibre foods, will not only supply far fewer calories, but by virtue of their bulk, will tend to prolong the ‘full-up’ feeling thus reducing appetite and promoting bowel movement (intestinal peristalsis). This is very important because constipation is still one of the commonest disabilities in the affluent West and laxatives are in such great demand that £4 million are spent on them each year in Great Britain and $49 million in the USA.