Dr. Shireen Kassam, MBBS, FRCPath, PhD
is a UK-based Consultant Hermatologist with a specialist interest in the treatment of patients with lymphoma (cancer of the lymphatic system). She is passionate about promoting plant-based nutrition for the prevention and reversal of chronic diseases and for maintaining optimal health after treatment for cancer.
So thanks, everyone. I’m going to take you through some aspects of nutrition and cancer
prevention and go through the evidence for this. And what I hope to cover in this talk are
– how diet contributes to cancer development
– how to reduce your risk of cancer
– how you might improve survival after a cancer diagnosis and of course what we feel is the
components of a healthful diet
What we know is that cancer is the top cause of premature death in the UK, accounting for 42 percent of cases of premature death and one in two men in one or two females now develop cancer. And this trend is only increasing and more than 50% of all cancers are due to lung breast prostate and colon cancer. And I’ll use these as examples as we go through and the best estimate is that around 10 percent of your risk comes from genes.
So, you can influence more than 90 percent of your chances of getting cancer. But overall Cancer Research, UK states that 40% or more of all cancers are print preventable through civets, through sensible lifestyle approaches. So, where have we gone wrong and these are my thoughts on this. So I think we continue to doubt and disbelieve epidemiological data. If we continue to rely and only accept randomized controls and studies we are not going to take on board all the evidence that we have in front of us. Now, and I’ve already used the example of smoking, there is not a single randomized study showing that smoking causes cancer. There is an overemphasis on the understandings of the genetics of cancer once the cancer is actually developed. And it’s just too late at that stage. We continue to separate diet into its individual components, you know fat protein carbohydrates whereas we have to start thinking about healthful patterns of disease. Sorry, not disease diet, We continue to hope that supplements can compensate for an unhealthy diet and there’s not a single study that shows that supplementing your diet can prevent cancer. We allow Pharma and sorry Farooq. If you’re still in their audience we continue to allow Pharma to design and run our clinical trials because as society and governments, we can’t afford these big trials. And Pharma relies on drugs that are going to make the money and not diet interventions. And we fail to apply precautionary principle and I’ll come back to examples of this. So, going back to 1892 Scientific American published, this cancer is most frequent among those branches of the human race. We’re carnivorous habits prevail and a few years later in new york times, it was noted in Chicago that cancer was increasing amongst meat-eaters, particularly among foreign-born using foods derived from diseased animals. And on the other hand, Italian and Chinese, practically vegetarians, show the lowest mortality of all. And since this time, we have a wealth of data that confirm these associations between a predominantly animal-based diet and the rising incidence of cancer. And here are just a few of them in the ethic study, which is close to home. It’s the European prospective investigation into cancer and nutrition followed more than half a million individuals and ten European countries for over 15 years. And we’ve learned a lot from it. The Adventist studies have given us a wealth of information. Harvard University has produced two large studies in women, the Nurses Health Study and in men, their health professionals follow-up study and the National Institute of Health American Association of Retired Persons followed half a million people between the ages of 50 and 70 and is one of the largest ever studies.
And overall the conclusions are clear, from all these studies that not only does a vegetarian diet reduced heart disease, but it reduces your overall incidence of cancer by up to 18 percent. And for some cancers, as even more than this. And so, what we know is that cancer is predominantly an environmental problem and we know about smoking more than 90 percent of lung cancers are caused by cigarette smoke but what we fail to recognize is that diet is equally important. Maintaining a healthful weight, limiting alcohol sensible exposure to Sun and exercise are equally important. And where do these environmental lifestyle aspects sit in their process of cancer development?! So cancer develops in three stages like initiation, promotion, and progression. Initiation happens all the time as cells in our body minute. But on minute are being damaged by our genes, by viruses, by chemicals, by toxins, but not all of these damaged cells survive and not all of them become cancer. But over a period of years and decades, there’s promotion where these damaged cells can either lie dormant or they can develop and grow because they’re being given a growth environment and become clinically evident. And the later stages where it’s too late is where it, it’s progressed and there are metastases all around the body. So what do we know about our current animal-based diet? So, one of the major factors and this is not about fat shaming or, it’s stating facts that obesity is rising and obesity is increasing our risk of cancer. So at the moment, seven out of ten of us are overweight and three out of ten of us, are obese and these trends are only going to increase. And we know that at least 13 types of cancer associated with obesity. So some of our Communists such as breast cancer and bowel cancer and some of the rare really difficult ones to treat such as pancreatic and esophageal associated with being overweight weight. But what we know about diet and this slide is from following 60,000 Adventists in California, that those that maintain a healthful weight are predominantly plant-based. You can see here that the vegans are the only group that is within the normal healthy. BMI and how do we believe Abby City is causing cancer?! Mainly because fat cells lead to the production of hormones.
So we’ve heard a lot about estrogen and estrogen is fueling female cancers such as ovarian womb cancer and breast cancer there are higher levels of incident and insulin-like growth factor. When there’s an abundance of fat cells and in addition being overweight and having excess fat cells as an inflammatory environment in the body which leads to the production of chemicals and cytokines as promoting growth. And the other consequence of obesity that we’ve heard a lot about, is the increased risk and rise of chronic disease and this study was published just earlier this year in the BMJ looking at more than 400,000 people from Taiwan and showing that cancer death and cancer incidence was much higher in those who already had an underlying chronic disease, whether it be lung disease kidney disease heart disease or diabetes and up to a third of cancer deaths are being contributed to by an underlying chronic disease. So, despite the fact that I don’t want to break down diet into individual components. we have known for a long time that animal components, whether it be fat or protein, is associated with rising cancer rates. And this is from the China Study, which quotes a study published in 1986 in the Journal of cancer, showing that as countries increase their intake of fat on the x-axis. You can see the rising rate of cancer and there is breast cancer and the rate of dying of breast cancer increases with the amount of animal fat but when you do the same graph and look at plant foods and plant fats, you don’t get this linear Association.
And since this time, we have further studies that have shown that the higher intake of saturated fat which only or predominantly comes from animal-based foods there’s a higher risk of breast cancer, aggressive prostate cancer and interestingly even if you’re a smoker you know the amount of saturated fat you’re eating and influences your rate of getting lung cancer. And of course, you can’t separate fact from protein and this study followed more than 6,000 Americans over 18 years and showed that as the amount of protein, particularly animal protein, in the diet increases, you can increase your risk of cancer by four times. Whereas, a low protein diet mainly played May made up of plants results in a lower incidence of cancer and the w-h-o in 2015 based on a large number of dates. Data and studies produced by the International Agency for research into cancer, have classified processed meats and red meats as a carcinogen. So processed meat causes cancer. It’s a group one carcinogen and it’s contributing to 20% of all colorectal cancer in the UK and red meat’s a probable carcinogen.
So this is where I come back to the precautionary phew you know we don’t know for definite. It causes cancer, but if it probably causes cancer, of course, we should limit it in our diet. and why is this so, we’ve heard about the heme iron and causing a pro-oxidant environment and giving rise to high levels of free radicals so he- toxic to cells it also leads to the formation of nitrosamines which are carcinogens the nitrates and nitrites that they are used in the processing of meat and give it it’s red color and stop the production of botulism toxin, also cause the production of nitrosamine and for an example one hot dog results in the same amount of nitrosamine in the body as for cigarettes. And of course if you’re taking in these toxins and with the processed and red meats, you’re denying yourself the benefits of the health of the plants, which other that animal foods are devoid of fiber antioxidants and phytochemicals.
And it’s not just about animal foods. It’s about the type and the quality of diet that we’re eating. So this is just hot off the press and the BMJ that processed foods and they talk about ultra-processed foods that are so far removed from their initial ingredients that have used additives chemical salt sugar. And that have used cooking methods such as frying that result in the generation of carcinogens like acrylamide. And these processed foods are resulting in a 10 percent rise in the risk of overall cancer and just briefly to touch on dairy. I mean this quote really says it all for Michael clapper, the great proponent of plant-based nutrition. The purpose of cow’s milk is to turn a 65-pound calf into a 400-pound cow as rapidly as possible. So it’s full of growth fluid and it’s clear now that dairy, whether it’s milk and cheese is associated with increased risk of a number of cancers. But particularly prostate cancer and a large number of meta-analyses confirm this association. So why do we think that animal foods dairy result in increase in cancer rates? And it’s one of the main mechanisms, Is the role of insulin-like growth factors our igf-1 and we know this is important in the development of cancer because there is a group of individuals who have a rare form of dwarfism called larren syndrome. And they have a genetic defect in the growth hormone receptor they have particularly low levels of igf-1 and they’re virtually immune from cancer and also from diabetes, despite being overweight. And what we know is, our diet influences the level of igf-1 so this graph shows that on the left-hand side, a vegan diet results in the lowest levels of igf-1 in the blood and it also leads to a 40% rise in its finding pod proteins as mopping up all this free i GF one and that’s compared to a low-calorie diet in the middle and a Western more traditional anime animal-based diet on the right-hand side and we can influence our levels of igf-1 within a few days.
So, this study took a group of overweight middle-aged men and put them on a plant-based diet and asked them to exercise and within 11 days they had a significant reduction of igf-1 levels in their blood. And in the longer term, this reduced further the other hormone that is significantly different in the blood of plant eaters compared to animal eaters as estrogen. And so the hashed line at the bottom is data from the China study looking at individuals in rural China and the graph above in solid is comparing it to British women at the time and the lifestyle lifetime exposure to estrogen is about 30% less on a plant-based diet. And then we come back to the precautionary principle. We know that viruses cause cancer HIV htlv1 hepatitis B hepatitis C, we know that animal viruses can be transmitted to humans so slaughterhouse workers in the poultry industry killing chickens and turkeys all day long have a 9 times increased risk of pancreatic cancer and liver cancer and we know this is due to the transmission of a wart virus. So when it comes to viruses that we can detect in our blood, this is an example of bovine leukemia virus which this study showed to be present in not only normal breast tissue on the left-hand side but in 60% of breast cancer specimens you can see find evidence of the bovine leukemia virus.
Now people will say this as just correlation and not causation, which is true at the moment. But what are we doing with bovine leukemia virus in our blood? And surely we should have a take a precautionary view and not ingest the virus until we know it’s safe to do so. And then just touching on and what we drink alcohol, unfortunately, is a toxin and it’s associated with increased risk of at least 7 different types of cancer and when it comes to cancer risk, there is no safe amount to drink. So just to move on to what we consider a healthful diet and anti-cancer type diet, we come back to this power plate and we’re talking about fruits, grains, legumes and vegetables. And we’ve already heard about Denis Burkitt, an irish surgeon who did a lot of missionary work in Africa. And back in the 70s, he noted the beneficial effect of fiber. So he noted that those on a minimally processed diet eating mainly plants that virtually never got bowel disorders, whether that’s bowel cancer appendicitis inflammatory, bowel disease but as soon as your diet shifts onto processed food and animal foods the risk of tumor increases and since his study and his anecdotal evidence and we’ve had a large number of meta-analysis showing that the more we eat in our diet, the lower our risk of colorectal cancer. And also, last year the World Cancer Research Fund published a statement saying that the consumption of whole grains probably protects against colorectal cancer. And it’s not only the fiber but also the other nutrients in whole grains. And some of these nutrients we’re talking about are phytates, which are particularly good for protecting, preventing cancer and phytates are particularly high in legumes.
So beans and pulses and beans and pulses have been shown to reduce your risk of cancer. And this paper that’s quoted here, is a subanalysis of the pretty med study, which showed a 30% reduction with the more beans and legumes that you’re eating. And there’s also a phenomenon called the Hispanic paradox, where Hispanic Americans are living longer and getting less cancer despite the fact that they are just as overweight and obese as the non-hispanic Americans. And it’s thought to be their bean consumption or at least one of the factors as their bean consumption they eat about a third of all the beans eaten in America. And when we talk about beans, we also have to include soy and we’ve already learned today that soy is good for us, whether it be for reproductive health or heart health. But for certainly for cancer, we’ve got enough in our evidence to support the role of eating soy in the diet and this reference here is from a meta-analysis of 18 studies, looking at breast cancer incidence. And there’s a lower incidence in those who eat soy, there’s a lower risk of recurrence if you’ve had a diagnosis of breast cancer. And also it’s associated with living longer, after a diagnosis of soy. And it’s those isoflavones, the phytoestrogens that are acting in a slightly different way from human estrogen. And the other food that is also high in a phytoestrogen, is flax seeds. And they really should be incorporated into our daily meal plans because they are precursors of lignin and in the food then lignans are also phytoestrogens and they’ve been randomized studies in breast cancer and prostate cancer showing a beneficial effect in those who already have a diagnosis of cancer. And of course, fruits and vegetables are full of anti-cancer properties. The phytonutrients, the polyphenols, all those things that we know about.
But this study from 2017 brought together 95 different studies showing that increasing your intake of fruits and vegetables probably up to 10 portions a day leads to a significant reduction and not only all-cause mortality but around a 14% decrease in cancer incidence. And there’s some particularly healthful fruits and vegetables. So the red color in tomatoes green red peppers and chilies have lycopene, which is particularly anti-cancer properties cruciferous vegetables which are broccoli and kale and cabbage have precursor substances to sulforaphane which has anti-cancer properties. Berries are probably one of the most healthful fruits and vegetables to incorporate daily in your diet and then the Allium family which is the onions, the garlic leeks that lead to the generation of organosulfur compounds and for the medics and the audience we are beginning to understand how cruciferous vegetables work particularly in the gut. So stomach acid converts the indoles from these cruciferous vegetables into ligands for the aural hydrocarbon receptor, which is found on the lymphocytes in the gut. And this activates the lymphocytes into having a pro immune effect and preventing damage to the gut lining so it’s never too late. This study again bringing in Dean Ornish, he randomized 93 patients with early-stage prostate cancer, putting them on a plant-based plus exercise and stress relieving activities. And he had a control group that carried on their normal lifestyle and after a year, there was a significant reduction in the prostate-specific antigen level in the lifestyle group. And whereas, in the control group, there was an increase in the PSA suggesting cancer progression. And after two years the control group 27% of them needed intervention such as radiotherapy or surgery compared to only 5% in their lifestyle group. And when he took the blood of these individuals in the lifestyle group and dripped them over the cells of prostate cancer in the laboratory at baseline before the intervention they could only stop the growth of prostate cancer in the laboratory by 9%. But after a year this had increased to 70% and there is evidence now to suggest that changing your diet and altering your lifestyle after cancer diagnosis, can improve your chances of surviving and reduce your risk of recurrence for colorectal cancer, prostate cancer, and breast cancer. And when it comes to drinking, the most healthful drink appears to be green tea. There’s a lot of laboratory evidence supporting this, not so much in humans, but it seems to be beneficial for precancerous lesions such as in the gut, in the cervix, in the oral cavity and particularly prostate cancer as well.
The cautionary note here is, that probably shouldn’t take them as pills because they’ve been associated with liver damage. And also they’re certainly chemotherapy agents that interact with green tea so do check if you’re on chemo whether green tea is okay or not. And with all these foods and plant substances they appear to act to all stages of development of cancer so initiation promotion and progression and then talking about spices we should incorporate them liberally into our diets and the king or queen of spices is to murica there’s a lot of data on what we believe to be the active ingredient which is curcumin. But actually, they’ve been studies done with tumeric that is that has curcumin taken out and there still has healthful properties. And again, we believe that it works for all the different stages of cancer development. And the studies are mainly supportive in colorectal cancer, some data, and pancreatic cancer, but probably the best data and there are randomized control studies are in early stages of myeloma a type of bone marrow cancer. And again when we look at this as a little busy but what it shows is that curcumin works at all aspects of cancer development, whether it’s to prevent damage to DNA, whether it increases the death of these damaged cells or whether inhibits the growth of blood vessels such that the cancers can no longer grow any larger. So in summary, I hope I’ve explained how a large proportion of cancers are preventable through our dietary choices and of course, I haven’t mentioned other really important things like exercise, stress relieving active activities. An animal-based diet is contributing to this high cancer rate, but so are processed foods. So we can, we can’t afford to be junk food vegans and a whole food plant-based diet will reduce our overall risk of cancer. And I’ll leave you with this quote, just to read for yourselves thank you.