John_Yudkin_-_Pure_White_and_Deadly_revised_1986_OCR

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- - -------------------- Pure, White and Deadly the liver - that is, an increase in the sort of 'scar tissue' that precedes the development of cirrhosis of the liver. This research was carried out by a group of scientists led by Dr Charles Best, who was one of the people responsible for the discovery of insulin in 1921. Other researchers have repeated the work of Best and his colleagues and produced the same results. All of this earlier work was done with rather special diets lacking particular nutrients. That is why the research team at Queen Elizabeth College has been looking at the effects of our routine diets, which are not deficient in any obvious way, and differ only in whether or not the carbohydrate part of the diet includes sugar. The most recent experiments have used extremely sensitive biochemical analyses to detect in the blood and in the liver the chemical fragments that the body uses to build up the collagen that is increased in liver fibrosis. Collagen, which exists in several forms of slightly different chemical structure, is the protein that is present in the walls of the body's cells, and also makes up a great part of the connective tissue that exists in the sinews or tendons, in cartilage and bone and in scar tissue. Our research has revealed that in sugarfed rats there is a distinct increase in these fragments, both in the blood and in the liver, long before it is possible to detect fibrosis in the liver with the microscope. The same increase is seen in rats with diabetes and in human subjects with cirrhosis of the liver caused by chronic alcoholism. Is there a link hetween sugar and cancer? There are some cancers that appear to have become more common in the last 50 or 60 years, and that also appear to be more common in the affluent than in the poorer countries. So I thought it might be worth while to see whether there was any relationship between the numbers dying from these cancers in several countries, and the amounts of sugar that their popUlations consumed. The usual snags faced us with the epidemiological studies. How many countries are there that keep proper records of the causes of death in their populations? Even where records are kept, how sure can you be that the diagnosis of cancer is correctly made, or made on exactly the same criteria, in different countries? Some sorts of cancer can be diagnosed fairly readily; others are 136 A host of diseases often misdiagnosed. Because of this, we gave most attention to three or four where the experts tell me that there is a reasonably good chance of correct diagnosis. The evidence at present comes chiefly from a study of international statistics and takes the form of an association between the average sugar consumption in different countries, and the incidence of tW9 or three particular forms of cancer. The cancers that seem most likely to be related to sugar consumption are cancer of the large intestine in men and in women, and cancer of the breast in women. The death-rate for these three cancers in different countries is quite closely associated with average sugar consumption, to about the same extent in fact as the association between sugar consumption or fat consumption with the death-rate due to coronary disease. An example is found in the international statistics for 1977-9 for breast cancer deaths in women over 65. The five countries with the highest rates are, in descending order, the UK, the Netherlands, Ireland, Denmark and Canada; the highest levels of sugar consumption, again in descending order, are in the UK, the Netherlands, Ireland, Canada and Denmark. On the other hand, the lowest mortality, in ascending order, is in Japan, Yugoslavia, Portugal, Spain and Italy, with the lowest sugar consumption in Japan, Portugal, Spain, Yugoslavia and Italy. My own observations of the association between sugar and cancer of the intestine and of the breast were made several years earlier than the study I have just quoted. I calculated what are called the 'correlation coefficients' between these cancers and sugar consumption in all the countries for which statistics were then available. Let me explain first what correlation coefficients are, and let me take as an example the relation between people's height and weight. On the whole, the taller people are, the more they weigh. But it is all very well to say that there is 'on the whole' this association between height and weight; it would be better if we could say how close this association is. Supposing that it was a precise and exact association, so that the person who was only a little taller than another would inevitably be heavier, and one still taller would be still heavier. If this were so, you would say that the correlation coefficient was 1'0. Supposing on the other hand - and this is even more unlikely - that there was no relationship whatever between height and weight, so that it would be just as likely for a man weighing 150 pounds to be five feet tall or six feet tall. In this case the correlation coefficient 137
Pure, White and Deadly would be o. In fact, there is a relationship, but not a precise one; tall people tend to be heavier. If you work it out exactly, for adult men the correlation coefficient between height and weight comes to about 0·6. The correlation coefficients I have found so far for cancer and sugar consumption in different countries are as follows: Cancer of the large intestine in men: 0·60 Cancer of the large intestine in women: o· 50 Cancer of the breast: 0·63 However, such international statistics, as I have stressed repeatedly, can do no more than give a clue as to the possible role of sugar or fat in producing disease. But there are indirect studies that suggest why sugar might increase the risk of women developing cancer of the breast, and of both men and women developing cancer of the large bowel. During the past ten years the development of cancer of the breast has been linked with the female sex hormones, especially oestrogen. Evidence for this association comes from studies in several different countries. It has been suggested that cancer of the bowel may be caused by a high concentration of insulin in the blood, but a more likely possibility, put forward by workers in America, Hawaii and England, is that, like breast cancer, it is oestrogen that is involved. Again, there has recently been an increase in the incidence of testicular cancer in young men, and it has been shown that their mothers were often overweight during pregnancy, and have an increased concentration of oestrogen in their blood. Whatever is ultimately shown to be the cause of these cancers, the fact is that a high consumption ohugar can produce an increased blood concentration of both of these hormones - insulin and oestrogen. There have also been suggestions that other dietary components might be involved in causing cancer, especially of-the bowel. One suggestion blames a lack of dietary fibre; a second is that it is caused by an excess of saturated fat and a deficiency of polyunsaturated fat. I have already explained why, on evolutionary grounds, dietary fibre, especially from cereals, and polyunsaturated fat, largely from oil seeds, are not likely to have been significlijlt contributors to the diets of our ancestors, long before there began to be a high prevalence of the diseases of affluence. Moreover Japan, with a very low 138 A host of diseases incidence of bowel cancer, has a fibre intake very similar to that of the UK. And, experimentally, it is polyunsaturated fats rather than saturated fats that tend to produce cancer in animals. Sugar and drug action Let me here add one more interesting effect of sugar, although no one has yet pursued it sufficiently to see if it has any practical application. A dozen or so years ago, some of my colleagues looked at the question of whether diet has any effect on the action of drugs. They gave a common sedative drug, pentobarbitone (Nembutal) to rats that had been fed on a diet in which the carbohydrate was either starch or sugar, and they recorded how long the animals slept after taking the drug. They found that the rats taking the sugar diet slept for a significantly shorter time than did the rats taking the starch diet - on average 98 minutes compared with 141 minutes. This discovery raises several questions. Would sugar decrease the effect of Nembutal in human beings as well as rats? If sugar has this effect, do other dietary components behave in the same way? Can you deliberately decrease - or increase - the effects of other drugs by changing the diet? If so, would the effect be produced simply by changing the amount of sugar or other dietary component for just a day or two before the drug treatment begins, or even at the time it begins? Clearly, there is a lot more research to be done by nutritionists and pharmacologists before we have the answers to these questions. Sugar and protein One of the unexpected effects that we found when putting sugar into the diet was that it interferes with the body's use of the protein in the diet. We first noticed this when we fed our rats a diet that was low, but usually adequate, in protein. When fed on our normal diet with starch the rats grew perfectly well, but when we replaced the starch with sugar their growth was retarded. Looking more closely at the reason for this, we found that the sugar interfered with the body's use of protein, so that the rats lost protein instead of accumulating it as they should when growing. 139
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WHY DO PEOPLE EAT SO MUCH SUGAR? WH
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Also by John Yudkin THIS SLIMMING B
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Acknowledgements Introduction Much
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Pure, White and Deadly enormous amo
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Pure, White and Deadly protein food
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Pure, White and Deadly vation of ce
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Pure, White and Deadly nutritional
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Pure, White and Deadly 909 pups bor
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Pure, White and Deadly genetic chan
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Page 39 and 40: Pure, White and Deadly More recent
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Page 43 and 44: Pure, White and Deadly about nutrit
Page 45 and 46: Pure, White and Deadly polyunsatura
Page 47 and 48: Pure, White and Deadly have your he
Page 49 and 50: Pure, White and Deadly to by Keys,
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Page 53 and 54: Eat sugar and see what happens 14 E
Page 55 and 56: Pure, White and Deadly the walls of
Page 57 and 58: Pure, White and Deadly in fasting b
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Page 61 and 62: Pure, White and Deadly this point i
Page 63 and 64: Pure, White and Deadly causes both
Page 65 and 66: - - -------------- A pain in the mi
Page 67 and 68: Pure, White and Deadly made the gas
Page 69 and 70: 17 A host of diseases I now want to
Page 71 and 72: Pure, White and Deadly Number of de
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Page 81 and 82: Pure, White and Deadly will, I hope
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Page 87 and 88: Pure, White and Deadly implies that
Page 89 and 90: Attack is the best defence 21 Attac
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Page 93 and 94: Pure, White and Deadly The British
Page 95 and 96: Pure, White and Deadry and its role
Page 97 and 98: Pure, White and Deadly that the Ins
Page 99 and 100: Pure, White and Deadly that sugar i
Page 101 and 102: Pure, White and Deadly Chapter 6 Br
Page 103 and 104: Pure, White and Deadly Skin disease
Page 105 and 106: Index Index jaggery, 19 Kassen-Zahn
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