 Hi, I'm Jean Carper with Hospital Satellite Network and on this week's program, Medicine for the Layman, we take a look at the relationship between diet and cancer. Just what is the connection between diet and cancer? Some experts think that as many as one-third of all cancers are now related to something we're eating. They get this information from taking a look at animals in the laboratory and analyzing the eating patterns of people who go on to develop cancer. Now there are some new studies going on to determine exactly how you can change your eating habits to reduce your risk of cancer. Here to talk about that is Dr. Peter Greenwald, an expert at the National Cancer Institute. We visited Dr. Peter Greenwald to find out more about diet and cancer. Cancer is the second biggest killer in the United States. Diet is second to smoking as a factor contributing to cancer. Currently, about 40 percent of the body's caloric intake comes from fat. Dr. Peter Greenwald from the National Cancer Institute describes how diet can cause cancer. Diet affects your chances of getting cancer. We know that certain cancers may be affected by what you eat. For example, cancers of the intestinal tract, particularly the large intestine, are affected by what you eat. Also cancer of the breast and perhaps cancer of the prostate. The main things that we know about diet that people should pay attention to today are that fat in your diet increases the risk of getting cancer. Thus, you should cut down on the fats. We also know that fiber-containing foods such as any fresh or frozen fruits or vegetables, whole grain cereals and whole grain breads reduce your chances of getting cancer. We asked Dr. Greenwald how fat causes cancer cells to grow. We think that fat when it gets into the colon as you eat it, itself can be changed into cancer-producing substances or it can cause an increase in secretions into the bowel of bile. And this is acted on by bacteria in the intestinal tract to produce substances, chemicals that may lead to cancer or increase your risk of cancer. We think that fats also can affect the hormone balances in your body. It can affect the way different cells like the normal breast glandular cells act because of the way it affects the lining of the cell. And in this way can affect your risk of getting cancer. It can affect the likelihood of the normal cell changing to a cancerous cell. We asked Dr. Greenwald if fat is ever good for people. Fat, there is a value in a certain level of fat, but that level is way below the amount eaten by most Americans. Most Americans can cut down dramatically in the fat in their diet and get major benefits from that. It's only when you get far, far below what levels most people eat that we have a concern about essential fatty acids. Dr. Greenwald says there are things you can do to help reduce the chances of getting diet-related cancer. In the United States we have a diet that's higher in fat than almost any other country. We eat a lot of fried foods. I think cutting out the fried foods is a way of reducing fat. For example, if you're eating potatoes, a baked potato is a wholesome food. If you cut it up in a way that absorbs a lot of fat and deep fry it to make French fries, you have a problem. You're adding an unnecessary amount of fat to your diet and one that could cause harm. If you're eating meat it's perfectly fine to choose a leaner cut of meat, perhaps cut down on the portion size because meat does have some fat in it. But then you have a nutritious food. You can trim off the fat. Chicken or poultry without the skin on is very nutritious and low in fat. If on the other hand it's deep fried in a batter, as is done in many fast food restaurants, you lose the advantage of the lean poultry and you are eating a tremendous number of calories from fat and getting the fatty acids in the fat, which may be harmful. The National Cancer Institute recommends three simple steps to prevent diet-related cancer. Cut down on fats, increase fiber-containing foods, and keep trim. The main things to do, though, are just to learn a few principles that are easy to follow that don't take any major change in your diet. The first one would be to cut down on fats. You can do this, for example, by choosing the leaner meats if you're eating meat, trimming off the fat, cooking in a way that does not add fat, for example, don't fry. You can choose the non-fat dairy products rather than the higher fat ones. If you eat a variety of vegetables and fruits and whole grain cereals, which are good foods in themselves, you're likely to eat less of the fatty foods. You can choose low-fat salad dressings and take a fruit for dessert rather than a high-fat dessert. Dr. Greenwald also stresses that keeping trim is important because a relationship has been found between cancer and people who are overweight. There is a relation between obesity or overweight and cancer. We know that people that are quite a bit overweight do have a higher risk of certain cancers. In particular, they do get more cancer of the uterus, the endometrium or body of the uterus. They get more cancer of the gallbladder. There's probably more cancer of the breast, which is due both to fat and to more calories. There is a higher risk of some other cancers. We don't know completely the explanation for the relationship between obesity and certain cancers, although we do know that fat cells will affect the levels of estrogens and other hormones in your body. There is an interaction between overweight and the way in which fats and hormones function in your body. Dr. Greenwald points out that a relationship has been established between alcoholism and cancer. Alcohol and particularly alcoholism does affect your chances of some cancers. The reason I said alcoholism is that most of the studies relate to people that drink quite a lot and they also tend to smoke. They have the double risk factor then of heavy smoking plus drinking. We know that these people do have more cancer of the mouth and more cancer of the throat and more cancer of the liver and pancreas. The alcohol does increase the risk. If the smoking was stopped, there would still be a slight increase, but not as much as the combined effect of smoking and alcohol. The message is if you drink, do so in moderation. According to Dr. Greenwald, the food supply of the future may be healthier. It will be possible to have foods that are just as delicious, just as well produced and yet may have lower health risks by lowering the fat, for example. We also see opportunities through more research in the diet and cancer area to be able to be more specific about just what benefits you can get from dietary modification and to know more precisely what we can do to achieve these benefits. Currently there is no completely effective means of preventing cancer, but there are measures one can take to lower the risk of cancer through diet. This program will cover some of the risk factors contributing to diet related cancers. We'll examine some of the ongoing research in this area, and we'll look at some dietary recommendations and general dietary guidelines that you can follow. We know from studying cancer patterns in different parts of the world that about 80% of cancer is linked to the way we live. This slide gives you estimates of the frequency of risk factors that contribute to cancer. The leading risk factor for cancer is smoking, which leads to cancer of the lung and contributes to a variety of other cancers. In this country about 30 to 35% of all cancer is related to smoking. It has now passed breast cancer as the number one cause of cancer related deaths in women. Next to smoking, dietary influences are the most important risk factor contributing to cancer. Researchers estimate the percentage of cancer cases attributed to dietary causes may be equivalent to those associated with smoking. However, it is important to understand that the evidence upon which dietary estimates are based is much less precise. Exposure to certain industrial chemical pollutants contributes to about 5% of cancer. This exposure occurs mostly in a very small portion of the population working in fairly dirty, heavily exposed settings. Research shows these chemicals may be harmful to animal or cell systems. Thus it's prudent to limit future exposures to these chemicals, even though scientists cannot attribute much of today's cancer to these factors. Alcohol contributes to cancer in perhaps 3% of cases, and most people who drink heavily also smoke. Whether food additives contribute to a small portion of cancer is an ongoing debate. There are suspicions that certain additives may even be protective. Although this is not yet proven. How do scientists come up with these estimates? First, it is known that there are very big differences in cancer throughout the world. One example is Finland, a country with a diet not unlike our own. But in Finland, a heavy grain, high fiber bread is common in the diet. The Finns eat about twice as much fiber as we do. If you live in Finland, your chances of getting or dying from colon cancer are less than one-third than found in the United States. On the other hand, New Zealand, a developed but largely rural country, has a high fat diet and a high rate of cancer of the colon and cancer of the breast. Japan, which is industrialized, has very low frequencies of cancer of the breast and colon. When scientists look at evidence comparing cancer in different countries, they make an estimate of how much cancer is due primarily to the environment. Genetic factors may also contribute to cancer. However, the overriding factors are related to the way people live. In addition to variations between countries, scientists know that when people move from one country to another, their risk of cancer changes. One of the best set of studies were done on Japanese living in Japan, Japanese who moved to Hawaii, and those who moved to California. What scientists know is that when the Japanese moved to Hawaii in California, their chances of getting breast or colon cancer rose as they took on the American lifestyle. We have similar evidence for breast cancer in Poland and the United States. The rate of breast cancer increased in Polish immigrants after they moved to the US when compared to Poles in Poland. There are socioeconomic and cultural differences, more evidence that environment contributes to cancer. For example, the black population in the United States has had a doubling of the death rate from cancer of the colon over the past 30 years. Today, this percentage is about equal to that of the white population. Scientists think this may be due to dietary changes, since it is thought that colon cancer is related to diet. In Los Angeles, the Hispanic population has only two-thirds the rate of colon cancer, as does the white population. Scientists think this is largely due to the amount of fiber in their diet. The most important dietary risk is fat. The more fat you eat, the greater your risk of getting cancer of the breast, cancer of the colon, perhaps cancer of the prostate, and other cancers as well. With fat and breast cancer, a number of different populations have been studied using different research methods and different investigators in different parts of the world. Now let's join Dr. Greenwald at the National Institutes of Health in Bethesda, Maryland, where his lecture on diet and cancer prevention is in progress. Dr. Greenwald describes some of these studies. In Hawaii, there was an analysis of five different ethnic groups. Very strong correlation was found between dietary fat and breast cancer. We noted the international changes. The time of World War II in England, the fat level went down for a few years as they cut down on meat and they ate more whole grain cereals. And vegetables. During that period, there was a lowering of the rate of breast cancer, which persisted for several years after the war. So we have evidence from epidemiology that breast cancer is related to fat. These are just some examples, as you well know, of the fatty foods. We have consistent evidence from the lab. If you feed an animal, we call it an animal model, that's an animal in which cancer is induced with a certain chemical, if you feed this animal a high-fat diet, it more frequently will get mammary tumors than if you feed a comparison group of the same type of animal, a low-fat diet. Based on this type of information, the National Cancer Institute feels it's reasonable today to make recommendations to cut down on fat. At the same time, it's crucially important to continue our research. At this time, there are two studies in their early phases of testing aimed at seeing if a very low-fat diet, half or about 20% of calories from fat, results in a lower frequency of breast cancer. We've identified women at very high risk of breast cancer, largely because of family history and other factors, and we're seeing if this 20% or 15 to 20% of calories from fat will lower the risk. Well, our general recommendation is to cut out a quarter of the fat. The study is to cut it in half. We don't feel we have enough precise information at this time to make the general recommendation of cutting it in half, but we think the study will give us more precise information about the biology of what's happening and about the time relationship. If you change your diet today, how long does it take to receive the benefit? Fat and calories are interconnected. This is an example of the trial referring to the 20%. Fat and calories are interconnected. We know that when people go on a low-fat diet, they tend to lose a little bit of weight. Because fat is a very concentrated form of food, concentrated in calories, and you store it more easily than you do the starches or complex carbohydrates. Another risk factor for certain cancers is obesity or overweight, which was the question many of the studies. I think the man on the left is eating heavy cheese as a nut popcorn, which is a good high fiber food. About the same types of cancers are related to obesity. It's, well, cancer of the gallbladder, which is not very common, but cancer of the breast, probably prostate, maybe several others. I'd like to go from here to the third risk factor, which is fiber. By fiber, we're really talking about a food that comes only from plants as part of the cell wall of plants. And it usually gives the structure to the cell wall. It's a group of substances that are not easily digestible. They tend to stay undigested until the lower part of the colon. They add bulk to the stool. As with fat and breast cancer, we have the same sort of international variation differences between countries. But in this case, fiber is protective. So what you're aiming for is to raise the fiber in your diet, perhaps double it. We noted the country of Finland with less than one third of our colon cancer death rate. In northern India, the Punjabis eat a diet high in vegetable fibers. And they have a very, very low rate of cancer of the colon, much lower than in southern India, where there's a low fiber, high rice diet. In Israel, there was a carefully conducted study by excellent investigators of colon cancer patients compared to other people. The colon cancer patients were eating more fat and less fiber, again, showing that these things contribute to risk. In England, there was a correlation of different geographic parts of the country. And it showed that the people in areas that ate more fiber, particularly one type of fiber that's present in bran, had lower rates of cancer of the colon. In San Francisco, another study was done of black colon cancer patients, and it was found that they were eating more fat and less fiber. Again, we have a consistent threat of evidence through a number of different studies, all tending to suggest the protective effect of fiber. Well, I said all, but actually you never get complete consensus in science. Actually, there are maybe 22 different studies that look at this question in different populations. About three quarters show the protective effect of fiber. One quarter show no effect. None show harm. When we look at these studies, we have to look at the details of the research methods. That's what the scientists do. And we try to explain the discrepancies. In this case, we cannot think of any type of systematic bias that would cause, by artifact, an untrue effect related to the benefit of fiber. We think there's a real benefit. We can think of a number of possibilities that could cause some studies not to show the difference. One problem, which you probably realize if you think about it, is that it's hard for people to remember what they ate, especially what they ate a few years ago. And this tends to dilute out the differences in the study groups. We also have some populations where the whole population does not eat very much fiber. And if you do a study in that type of population, you may not see a difference. So we think we have the evidence. Again, it's supported by lab data. And I'll just mention a couple of ideas of what we think might be happening. This refers to mechanisms in the bowel. On your left, you see that fat in the bowel may increase the risk of colon cancer. Fiber is also there a little bit. The fat may be, it's not proven yet, but we have some evidence that the fat may be acted upon by bacteria that normally occur in your large intestine. And the fat also may increase bile secretions, which may be acted upon by these bacteria. These may then form mutagens, things which cause genetic damage in bacteria. And it's possible but not proven that these mutagens lead to the cancer. Fiber has other effects. It increases the bulk of the stool, which may dilute out things that contribute to cancer. We think it may lessen the rate at which these mutagens are produced by bacteria, because the bacteria seem to be happier in the fiber environment. And it may bind and cause the excretion of some things like the fats. I want to mention a few other risk factors. One is alcohol. I probably should say alcoholism. Most of our evidence does not relate to alcohol per se, although there is a little bit of that. But to heavy drinkers, the studies were done of heavy drinkers. These people have other differences in their life besides the heavy drinking. They may not be too well nourished. They usually smoke heavily. And probably the best thing they could do is avoid smoking and driving. Have to think of the rest of us. So I'll go through some of the others later. This is just to kind of summarize the high fiber ones on the left being good and the others things to cut down on. Well, at this point, I think we might highlight for you a bit of the research going on. Thus far, most of the evidence I discussed came from epidemiology, from human population studies. We have complementary research in the lab. We also have a very intensive program of human cancer prevention trials. Part of this area is called chemo prevention. By that, we mean that we're adding specific defined chemicals to the diet to see if it can lower the frequency of cancer. This does include vitamins like vitamin A, C, and E, certain minerals like certain types of selenium. It also includes synthetic compounds. Part of the hints that lead us into these human trials are epidemiology. But there are also laboratory studies. And let me just give you a couple of examples. In 1955, there was an English doctor named Liznitsky. What she did was she had a way of growing in a little watch glass mouse prostate cells. She put in some chikembryo and chikserum, a little concoction in the watch glass. And these prostate cells would grow. If she then added a chemical which causes cancer in animals, chemicals called methylcholanthrin, she could get the cells to change. They wouldn't change all the way to cancer, but they would become abnormal in an in-between type stage. She then found that if she added vitamin A, she would prevent the change. And in fact, if the vitamin A was added a little bit after the carcinogen, after the chemical, she still would prevent it. That has important significance to us because it's implying that the later part of the process in which cancer develops can be affected. To you and I, it means that if you make a change in your 40s or 50s or even later, you may well derive the benefit of the change. It's an effect on what we call promotion. We have better studies now, more sophisticated ones. One done here at NIH is by Dr. Sporn and his group. What they've done is they have a model where they put a tube into the stomach of a rat or a mouse and squirt in a cancer-producing chemical. After about six months, 40% of the rats have cancer of the bladder. With the best of our inhibitors, these are compounds related to vitamin A, but not what you can buy in the health foods who are not nationally occurring. With the best of these compounds, the frequency of bladder cancer can be reduced from 40% to 5%. Another model is another chemical called MNU, which when you inject into a rat will lead almost 100% of the time to mammary tumors, breast tumors. With the best of our inhibitors, we can reduce this from 100% to 20%. So we have that in a number of other models. And what we're seeing is consistency in different animal species with the same inhibitors working enough that we think there must be something in it for people. And what we've begun for the first time in history in the past two years are human cancer prevention trials based on this type of knowledge. They're now 26 in progress. Let me describe some of the trials for you just so you get an idea of them. There are some trials that are aimed at benefiting the population at large, most of us in this room. The best known is a study of US physicians. The doctors are the guinea pigs. There are 22,000 doctors in the United States taking part in this trial. It's done by Dr. Hennigans at Harvard. The doctors are taking a pill called beta-carotene. This is the orange color in carrots, and it turns into vitamin A compounds in your intestines. They're taking the beta-carotene to see if it will lower their chances of getting cancer. Some of them, they don't know who is who, take an identical pill called a placebo. That's part of the study design. Neither the doctors nor the investigators know who gets the beta-carotene or who gets the placebo. This is an example of a cancer prevention trial, the benefits which would apply to the population at large. We're doing another study of this type in Finland in a group of people that smoke much more heavily than do US doctors, most of whom have stopped. A second type of study aims at people who have a very high risk. In Seattle, there's a study of workers who smoke and who are exposed to asbestos. They have x-ray evidence of damage from asbestos, but not cancer. Up till now, all we can tell these men to do is not to smoke. We do not have a good early detection method for lung cancer. The study then is to intervene after exposure to see if we can prevent the onset of cancer. A third group of studies aims to prevent progression of a medical condition that is not cancer, but it predisposes to cancer. This depicts a study that I and others here at the National Cancer Institute are assisting our colleagues in China in conducting. It's a study aimed at preventing the progression from a precancerous condition of the esophagus to cancer. It's done in a part of the world, one part of China, not all of the country, but one part where one out of four deaths are due to cancer of the esophagus. It gives us a better method of conducting the study. What happens, as shown on your right, is that a little tube is put into the stomach that has a balloon on the end and a little gauze over the balloon. That's put in and pulled out. And it's like a pap test. The cells are put on a slide and looked at under a microscope. Those that have abnormal cells are then studied. First of all, they have a swallow of barium to prove that they don't have cancer. And if they have this precancerous condition but not cancer, they're entered into the trial, which aims to see whether or not we can prevent progression to cancer or cause regression of this abnormal lesion. And again, we're using, in this case, different vitamins and minerals. While we bring along in the lab some more potent inhibitors that aren't yet fully tested for safety, at the present time, we know of about 350 things that may have some potential for cancer inhibition. We've sifted through them to throw out those that you would never put into a person because of toxicity. And we're testing in a systematic process about 68 different compounds to see which ones succeed in showing efficacy in a number of animals, relevance to humans, safety, and a number of other features. Another thing we look for is whether there were late in the cancer induction process. Because we think that means that you might benefit by starting late in life, not starting as a teenager and taking something throughout life. Well, that's just to give you an idea of some of the exciting research efforts. There's a great deal of basic research that is crucially important that complements these clinical prevention trials. Let's go back and just take a look at the guidelines. The first is to cut down on the fat in your dial. We think the easiest way to do that is just to learn a few principles. You don't have to memorize any menus. Just take the foods you eat, and if you eat dairy products, choose the low-fat ones. If you're eating meat, take a leaner portion, cut down on the portion size, trim off the fat. Choose cooking methods that are low and fat. The worst one's frying. If you take a good bit of potato, cut it up in a way that it soaks up fat, you have a problem. If you fry, you could use a nonstick method. Most of the other methods do not add fat, like microwave does not add fat. Chicken is a very wholesome food without the skin on. If you put the skin on and deep fry it, you lose the advantage. Salad dressing, some are high-fat, some are low-fat. And there are good fruit choices as an alternative to certain rich desserts. A second is to keep trim. Part of this is net energy balance, an interplay between exercise and calorie intake. This isn't only fiber-containing foods, but it's healthful ones. Eat fiber-containing foods. By that, we mean any whole-grain cereal or bread product, any fresh or frozen fruits and vegetables, the legumes, the peas and beans. And if you roughly double that, what most Americans are eating, we think there's no risk to that. At very high levels, there might be a little binding of calcium, which you can offset with skin milk. But at the level we're recommending, we don't think that that occurs. I didn't want to leave this one out because it's a key factor. Finally, I wanted to end by going through a few questions that we sometimes get. One is, can you benefit by changing your lifestyle at middle age or later? We think the answer is yes. We know that from the migrating population studies. We know, like, the time trends in places like England during the war, where when the fat went down in the diet, the risk of breast cancer fell off right away very soon. We haven't pinned down completely what the time relationships are or the magnitude of the effects. That will require more research. What about sweetening agents, saccharine, cyclomates? Again, we don't have anything in the way of human evidence that these cause harm. There have been some suspicions with some of them that come from very high doses in animals. But we don't really think that there's any risk. The FDA went through it well. There could be a question if children start drinking these and have fairly large amounts throughout their lifetime. We just, it just has not been feasible to do studies of that question so we don't know one way or the other. But we think the evidence we have is that there is no risk. That's at least no measurable risk. Something I sometimes hear is that there's so many things that cause cancer that people throw up their arms and say, why bother? The fact is that that's a misunderstanding and it's a problem. There are only very few things that are important to most people. Don't smoke and change your diet to reduce the fats, increase the fiber and keep trim. The other things that you hear about almost every day either are unproven or are of trivial importance to most people. They just do not affect the cancer risk of the average citizen. Now I'm not saying that we shouldn't be cautious about chemical contaminants. There is a possibility they could cause future harm and we want to limit those exposures. But we do not have evidence that much of today's cancer is due to those chemicals. Vitamin pills. Well, the studies that we have come from studies of people eating foods. We just don't have much research evidence one way or the other on people taking supplements. Therefore, we don't make a recommendation on supplements. We know that the people eating the foods have the lower cancer rates. It'll take a few years before we have enough information one way or the other to make this recommendation. My own feeling is that I don't feel strongly about the balance one a day sort of thing, even though we don't have the evidence. I think we also don't have sufficient research results on nutrition in the elderly or nutrition in some people that are on very restricted diets, the Vogue Readers types. We certainly would not recommend high unbalanced dosages. We know of harmful effects. For example, vitamin A can damage the liver, probably can cause birth defects and affect the skin. Well, finally, I'm optimistic. We know that there have been favorable trends in our society already. We think we can build on these. We know and can strive for a healthy population eating healthy foods. An informed consumer is a good step in this direction. A food industry that puts the choices on the shelves also helps. We think even in our regulatory processes, we can help to achieve this. For example, meat is graded. Right now, the incentive is that the higher grade products which are higher cost are higher fat. The meat industry and I think the U.S. Department of Agriculture are willing and considering modifying that sort of thing. So the incentive is there for industry to change their products. Industry is willing with consumer demand. And I think in the future, we will continue the trials, we'll be able to make them more specific, and we look toward ways for better cancer prevention in the future. I had a question. You talk about high fiber fruits and vegetables being good for you, but what about the pesticides we always hear being sprayed with? Yes. The question is about pesticide use. I would have included that under the additives which we discussed. Now, there are intentional additives, things that the food industry puts in the food that make it smooth or affect the texture or affect the shelf life and things like that. And then there are unintentional additives such as pesticide residues. Obviously, we don't want them there. It's better not having them. But we don't have evidence that cancer today has been related to the trace amounts that are present in some foods. Okay, and one other question. I've also heard about fish coming out of the ocean with cancer. And I don't know if we're eating it with cancer. That has any effect or there's been any studies done on that? No, there have been a few questions related to certain types of smoked fish in Iceland that was thought to be related to the cooking techniques that put different hydrocarbons from the cooking on the food and in several places. But there really is not a risk from fish. In fact, fish is a very helpful food. And one of the current research efforts has to do with fish oils. We think that they may be very useful from a point of view of reducing heart disease risk. And we're looking more into it in relation to cancer. One thing I should point out, since people want to lower their overall disease risk, is that the recommendations that we're making are just about identical to those of the Heart Institute, that if you cut down on fat and you keep trim, it's the same sort of thing that lowers your risk of heart disease. So you get a double benefit. Yes. I've got two questions. First, you mentioned in your introduction that you would entertain questions about diet as adjuvant therapy. And I wonder if you could address that point, in particular with reference to the claims of such as Linus Pauling and Vitamin C. Yes. What about diet as therapy? In general, diet may help keep people robust a bit. But there's no evidence today that we can impact life expectancy after diagnosis of cancer or that we can improve the response to therapy. So it's purely an adjunct. There are some useful purposes to it. I think the worst thing that can happen and does happen is that people delay or avoid the best of medical diagnosis in state-of-the-art therapy because they've chosen an alternative thing. That's the worst. And that can lead to death unnecessarily. There have been some studies of Vitamin C in cancer treatment. The best-known one by Dr. Mortell at the Mayo Clinic. He did replicate most of Linus Pauling's approach, although he used standard approaches to treatment protocols. And it showed no benefit at all from the Vitamin C therapy. Right. I think Dr. Pauling would reply to that as he did a last spring at nearby that they cut back all of a sudden. They gave the Vitamin C the way one would give chemotherapy and then stopped. Yeah. Well, that's not accurate. What happened was, as patients got worse on the therapy, they did discontinue the therapy. One final question. Yes. You estimated that 35% of all cancers may be diet related. Roughly, yes. And also emphasize the importance of research. Keeping these factors in mind, why then is only 1% of the National Cancer Institute budget related to devoted to nutritional research? That's not an accurate figure. Let me just tell you, there are four major research divisions in the National Cancer Institute. One of them is called Division of Cancer Ideology. That's research on the causes of cancer. A lot of the chemical carcinogenesis, the chemical animal work I described, the epidemiology, virus work. That's one division, one quarter of the program. The second one is the division that I run, which is called cancer prevention and control. Much of our diet research is in this area, the human trials. There are a lot of other things. A third one is biology and diagnosis. It's the basic molecular biology, molecular biochemistry. You may have heard of oncogenes and some very exciting basic science research that leads us into these other benefits. And the fourth one is a division of cancer treatment, which basically tries to come up with new therapies. Now, I'm not saying that we don't have some unfunded research opportunities. I think we do. But we have given a lot of priority to this area, and we'll continue to. Thank you very much. Yes? Yes, I was just curious. In your research, have you found any evidence of any toxicity with very high levels of beta carotene? No, beta carotene does not really have the toxicity that vitamin A has. As you eat larger and larger amounts, somewhat less is absorbed. You can turn orange if you eat too much. And that's not really, we don't know of any harm to that, but that kind of limits the dose in the trials. What happens is it exposes the blind, so the one getting the beta carotene knows it. So we stop below that dose. Yes? You say, keep trim. Is that because body fat stores the pesticides or whatever you eat in your diet? And what's the implication for very thin people? They keep trim, really. First of all, the evidence we have shows that those people that are sort of at ideal weight, plus or minus 10% or so, are best off. And you then have to speculate about what the mechanism is. We think that the mechanisms are more related to how fats are handled in your body, how they affect hormone levels, immune systems, and other things, and not to the fact that there may be some storage of pesticides, which is true, in your fat. Yes? Are you familiar with the macrobotic diet? Yes. And studies by Mr. Kushi? Yes. Do you agree with them? Now, the macrobotic diet, first of all, it's very hard to characterize some of these diets because people have a different interpretation of what it means. This one tends to be more vegetarian, with more emphasis on grains. And there's an indication to avoid meats. Also, an indication which could be a serious mistake to cut down on fluids. You know, there's some half truth in it. I mean, it's fine to emphasize grains and vegetables. That's just what we emphasize. When you carry it to an extreme and lose important nutrients or avoid fluids, which are very important, then you could have harm from it. Yes? Is there any difference between animal fats or plant fats? There is a difference between animal fats, plant fats, and fish oils, another type. In cancer, our best evidence today is to decrease total fat with heart disease. The ratio of the unsaturated plant oils to animal fats, which are saturated, is a bit more important. So at present, we think if you just cut down all fat, that's the best thing you can do. I think it's important to look at types of fats, but we don't have enough answers on specific types yet to make a recommendation. Not going to be a very pleasant evening when I get home. I can tell you. Is there any point in time after a heavy smoker has stopped smoking that his risk of getting lung cancer is any greater than the non-smoker? I'm not sure it comes down totally. There's been debate about that. But certainly within three to five years, you have a tremendous reduction in risk near the level of the non-smoker. And by 10 or 15 years, it's very near the non-smoker. Most people would say it may not be absolutely at that level, but it's quite low. In regard to your other remark, I think it is an important consideration. For example, when we look at the international differences in breast cancer, the countries that have about half of the fat as we do have a little below half of the incidence rate of breast cancer, there are about 100 countries that have a diet at a recommended level of cutting off of water. And they have tasty diets, like southern Italy, for example. And I think it's a matter of adjusting. When I was little, I used to drink whole milk, and I felt skim milk tastes like water. Now I drink skim milk and whole milk tastes like cream. I can't drink it. I think if you adapt slowly over time, you're not really giving up the pleasures of life. You're just adjusting and changing your taste a bit. What percentage of smokers actually get lung cancer? It's between 10% and 20% depending on the frequency of smoking, probably 5% to 10%, depending on the frequency of smoking. And the duration, whether they inhaled or not, 1 in 10 to 1 in 20, 5 to 10. A few years ago, we heard about the hazards of certain types of cooking methods. I didn't hear it. A few years ago, we heard about the hazards of certain types of cooking methods of using mutagens into meat, et cetera. What's the latest information on that? Well, again, there are mutagens on meats or foods that are cooked at very high temperatures, broiling at very high temperatures. We're not sure that they contribute to cancer, but there has been speculation about that, and it is under study. The epidemiological studies do not show an association. The lab people find the mutagens there, and that's where we're left at the present time. It's only with a very, very high-temperature cooking. What about nitrites? How serious do you think they are? I don't think nitrites are serious in this country. We do know of areas where there are important problems, but it may be prudent, again, as with some of the additive-type questions. We don't have proof of harm, but we do know that you do get nitrites in processed meats. That when you get them in processed meats, you may have a peak of a high level at once, rather than a kind of a steady, higher level that you might have, for example, there's nitrate in your water that changes the nitrite. You do know some nitrite comes from your saliva. These can transform into nitrosamines, which are cancer-producing substances. It's possible something like vitamin C or E will inhibit that process if you have them at the same time. We think that it's best to cut down those levels as much as we can without interfering with the processing and preserving processes that we also need, but we don't have evidence really in this country. We don't have proof of cancer. We have a concern to minimize risk. Yes? Two questions also. Could you say whether white breads and processed cereals have considerable or very little benefit in terms of fiber, this for children? White or processed breads? Well, I think you ought to look at the amount of fiber on the box. Cereal can be a healthful food. It's low in fat. Most are low in fat. They can be quite nutritious. I think if you can get your children accustomed to the ones that at least have a moderate amount of fiber or mix a little of the high fiber in with the other cereal, it might as well get used to it. Now, I'm not talking about a very young preschooler, but by the time they start developing their food habits when they're school children, you can try it a little. It's hard to do. I also just wanted, could you expand a little bit on your mention of the binding of calcium with too much high fiber? Well, there is a concern about osteoporosis in the country, hip fractures, due to thinning out of the bones. And it's an important problem. I think probably the third biggest cause of admissions to nursing homes after strokes and Alzheimer's disease are hip fractures. So we want to make sure that we don't cause a problem. As best we can tell, calcium is a complex thing. If you eat a lot of protein, you'll have binding. If you eat a lot of phosphates, you'll have binding. If you eat a huge amount of certain types of fiber, you may have some also. But we've looked into it in depth, and at the levels we're talking about doubling, you probably do not have a problem. At the most, maybe the amount of calcium in the quarter of a glass of milk could be bound, but it's probably less than that. I was concerned about somebody who eats quite a bit of TVP, texturized vegetable protein, and bran, would a calcium supplement help the problem? Or not? I'd have to go into it in detail. I really can't answer. I noticed that you mentioned the fact that people are improving their eating habits. This may be a little out of your line, but is there anything that we can do to encourage restaurants to prepare food in a non-fat way? Well, actually, there are mixed trends. There is a portion of our population, probably most of you who are interested in health, that have tended to improve their eating habits. There's health awareness and fitness in the country. There also are more fast food stores. There are some people that get 30% of their meals from fast food stores, and those tend to be very high fat. They tend not to have vegetable choices. I think the best thing that can be done is if people start asking for it, some of the fast food places have vegetable bars now. It is a problem. I think some of the packaged foods that are used because they're quicker to cook, both spouses working, for example, look for more rapid cooking methods, and some of those are high in fat, and you have to look for the ones that are lower in fat. So we have had mixed trends. I really don't know the answer to changing what's there in the market, except for a good public education. I think they're lagging behind the individual family. Right. Could you comment on the amount of salt and sugar in a diet and its effect on cancer? Salt and sugar. We really don't have an indication of risk for cancer from salt and sugar. Certainly for high blood pressure, salt is important. There's been debate about sugar, but not with cancer. Are any different with cooking in gas and electricity? Does it affect the food? No, I don't, gas or electricity, it doesn't matter, or microwave, no. Now let's recap the lecture. While numerous studies are still underway, one fact is clear. A change in eating habits and attitudes about food can reduce cancer risk. There are currently 26 clinical cancer prevention trials in progress. The results will create a better understanding of how nutrients affect cancer. In the meantime, scientists give the following advice. Decrease fat, increase fiber, such as whole grains, fruits and vegetables, and keep trim. Medicine can be complex and confusing, but the best health insurance is knowledge. Thank you for joining us for this week's Medicine for the Layman.