Indifference - the biggest enemy? continue...

Colon cancer update

Some recent findings to do with the prevention of colon cancer (one of the most common cancers) are heartening. Studies on human beings have shown that including less fat and more fibre in one's dietprobably lessens the presence of `mutagens' (substances which can promote the development of cancer) in the bowel contents.

A recent four-year study in the USA also produced interesting results. The subjects of the research were a series of patients with 'familial adenomatous polyposis'. This refers to a segment of the population with bowel polyps which are particularly prone to become cancerous. (Polyps are growths with a pedicle or stem which usually develop on mucous membranes.) These patients were put on a high fibre diet (about 22g of fibre daily compared with the usual daily intake of about 12g), the extra fibre being provided by commercial bran cereal. In all the patients, a regression or shrinking of the polyps resulted - an outcome which was regarded as very promising by the US National Cancer Institute.

Also interesting is the fact that elderly blacks examined in the Department of Gastroenterology at Baragwanath Hospital, Soweto, showed no evidence of polyps; indeed their bowels had the appearance and elasticity of that of white teenagers! Among old rural blacks, colon cancer is extremely rare and even among urban dwellers, its occurrence is only a tenth of that found in elderly whites. The significance seems to be that the diets of these people are generallymuch higher in fibre and lower in fat than those of their white counterparts.

Eating to combat cancer - a day's sample menu**

* Breakfast: Cereals (such as All-Bran flakes or Weet-Bix), or oatmeal porridge, with milk and sugar

* Orange juice, a poached egg on brown (preferably wholewheat) toast and a couple of slices of tomato

Tea or coffee

* Lunch: 2 or 3 slices of brown or wholewheat bread with margarine,cottage cheese, salad (eg lettuce, celery, raw carrot), an apple or a banana

Tea or coffee

Dinner: Fish or chicken (not fried), brown rice, baked or newpotatoes, a green vegetable, baked beans, gem squash and a brown roll

Stewed or canned fruit (eg pineapple) and yoghurt

**This suggested menu provides about 30% of energy from fat and about 20-25g dietary fibre.

The alcohol/cancer link

Too much alcohol is a risk factor for the development of several cancers, especially of the liver, oesophagus, lung, pancreas and rectum. But here again, little notice has been taken of calls to cut down and levels of consumption are still rising, not only in many Western populations but in all Third World urban populations as well.

What is a reasonable or safe alcohol intake? For the majority of consumers there is no health problem, since it is considered that the majority of people who drink do so moderately and never experience any harmful effects. The crucial question is: What is a sensible limit? The liver burns up one standard drink (a half pint of beer, a glass ofwine, a measure of whisky) in an hour. With this in mind, the following safe allowances have been put forward:

For men, four to six standard drinks, two or three times a week. Or, at most, from 18 to 20 standard drinks weekly. For women, two or three standard drinks, two or three times a week or, at most, 9 to 13 standard drinks weekly.

These recommendations (endorsed by World Health 1985) were set out by the London Health Education Council in a booklet titled 'That's the Limit: a Guide to Sensible Drinking'. The reason why the limits for women are lower than for men is twofold: firstly, in men, water makes up 55-65°/o of body weight and in women, 45-55%, therefore alcohol is more diluted in men than in women; secondly, alcohol is potentially more noxious in women than in men.

Smoking and cancer

Smoking is believed to be responsible, directly or indirectly, for about a third of total cancers. It increases the risk of certain diet-related cancers such as breast cancer, but appears to have little influence with others, such as cancer of the prostate. In many Western populations there has been a major decrease in cigarette smoking among men, although far less so among women. In the USA, current frequencies are 32% for men, but 26% for women. Nowadays more young women than young men smoke, and today's female smoker is a heavier onethan yesterday's!

In Third World countries, tobacco use is rapidly increasing - in African populations, consumption has doubled in the last 10 years. So the dismal view is that all tobacco-related cancers, especially lung cancer, will almost certainly increase in the years to come.

Indifference - the biggest enemy?

Against the background of all this evidence and the educational efforts of authorities worldwide, what are the chances that in the decades to come, people will change their eating patterns to protect themselves against cancer? Unfortunately, the experts agree that these chances are slim indeed. For one thing, they say, there is no record of any population ever changing from a palatable diet high in fat to a less palatable one which is lower in fat, for health's sake.

To justify this pessimism, it has to be admitted that despite all the evidence and the urging of respected authorities such as those mentioned above, statistics show that people in Western nations are not cutting down on their food and fat intakes. In fact in many countries - such as the US and Australia - obesity is rising. South Africa is no exception in this regard, since several reports havetestified to the high frequency of obesity in our inter-ethnicpopulations, especially among women. Obviously, food consumption in prosperous Western nations - and in 'higher-class' Third World urban populations - is governed mainly by pleasurable taste and hedonisticattraction.

The Cabbage Patch Diet

There has been a lot of discussion in the media about the valuable anti-cancer properties of fruit and particularly of 'cruciferous vegetables'. These are vegetables which have four leaves at the base of the stalk in the shape of a cross - hence the name. Cabbage, brussels sprouts, broccoli and cauliflower all fall into the group. These vegetables also provide us with a large amount of fibre. Along with many other fibrous foods, cruciferous vegetables are rich in vitamins A, beta-carotene, C and E. It has recently been discovered that these vitamins act as important defence mechanisms against damage to tissues and the impairment of their function due to 'free radicals' - compounds which are produced in the everyday working of our bodies.

The vitamins, which act as 'anti-oxidants' or scavengers, tend to lessen the damaging effects of bacteria and other parasites and also have an inhibiting effect on the development of cancer and other degenerative diseases. While these findings may tempt you to rush out and stock up on multivitamins, all authoritative dietary bodies are emphatic that it is infinitely preferable to increase your vitamin intake by eating more plant foods rather than by popping pills. (This applies particularly to vitamin A, which can be toxic in large doses.)

This is borne out by the well-known experience of some populations during World War II. During that time there was a significant drop in the consumption of fat and sugar - simply because they were not freely available - and a marked increase in the intake of less refined bread and of vegetables and fruit. In the populations most affected, there were varying decreases in dental caries, obesity, diabetes, coronary heart disease, constipation and appendicitis. Admittedly there was no clear-cut evidence of a fall in diet-related cancers, perhaps because the length of time these changes were in operation was too short. But the point of this story is that once wartimerestrictions were removed, dietary patterns reverted and frequencies of all the disorders and diseases mentioned returned to their former levels - and then increased.

A recent survey by the American Cancer Society showed that 'only 15% of those polled (white persons) reported that they had made significant changes in the foods they eat because of theirunderstanding of a possible diet-cancer link'. In the Tecumeseh Diet Study (also in the United States) in which peoples' perceptions of change were assessed after a 15-year interval, there was no fall in the intakes of fats and oils. And a survey in the Netherlands indicated that only 4% of the population were consuming a 'prudent' diet.

With increasing urbanization and prosperity, energy and fat intakes are rising in Third World populations to the levels consumed by their white brothers and sisters. Simultaneously, fibre intakes are falling to levels even below those of white populations. Education among urban Third World populations has certainly created an understanding that nutritional deficiency diseases, mainly in children, such as proteinenergy-malnutrition (marasmus, kwashiorkor), can be fought by making appropriate changes, and that adult nutrition is very important in the control of tuberculosis. However, to suggest that their increasingly palatable diet, with higher intakes of animal products, should now be modified to lessen their chances of developing 'killer' diseases in later life seems like a contradiction, and is largely ignored.

In the American Cancer Society study referred to, it came to light that blacks and Hispanics were less inclined than whites to alter their diets so as to reduce their risk of getting cancer - even though these minority groups appeared to be just as aware of the link between nutrition and the reduction of cancer risk. One reason stated was that blacks and Hispanics are more likely than whites to feel that they cannot afford the required nutritious diet. (In America, brown bread costs more than white bread and breakfast cereals, vegetables and fruit are comparatively expensive.)