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Craig G. Hurwitz, M.D.

cancer and Plant Based Nutrition

   

 

The beginning of the story of cancer starts with our DNA or genes.10 The cells in our body (whether breast, prostate etc.) contain our DNA (our genes). Our cells divide to add new cells in the growth of our body and to replace old cells. The same DNA or genetic code is passed on to these new cells. This process of cell division is controlled and not haphazard. Many cell types, including blood cells, even have built-in programmed cell death (apoptosis) as an integral part of their control.     


The first step or the initiation stage of a precancerous lesion begins with an altered or injured gene or group of genes. Some known agents that can injure or alter genes include a chemical or environmental carcinogen, ionizing radiation, a virus, a hereditary mutation, and free radicals (see Nutrition is a Symphony above). If healing does not occur, these altered genes are now passed on as our cells divide. The result over the years could be a precancerous focus that can initially grow (the promotion stage) and later even spread. The fundamental abnormality is the continual unregulated proliferation of cancer cells.


The injured or altered genes are not the only determinants of what later happens. The gene has to express itself.11 The environment of the altered gene, especially nutrition, can play a critical role in whether the gene remains quiet (dormant) or active (expresses itself). In the case of breast cancer, in addition to nutrition, the estrogen environment that bathes the breast cells also plays an important role in gene expression. Interestingly nutrition also affects the level of estrogens in the body.


Many human migration studies strongly suggest that diet and lifestyle are major factors in the development of cancer. For example, these studies have shown that people of the same ethnic background migrating to a new area become prone to the same type and frequency of disease seen in the host population. This was shown for breast cancer in Japanese women migrating to the United States in the 1950’s. The second and third generations of Japanese women moving to the United States from rural Japan developed the same increased rate of breast cancer that we see here.

        

The extensive laboratory studies by Dr. T. Colin Campbell and his team at Cornell and other investigators in rats and mice strongly suggest that nutrition can have a significant impact on cancer. One set of experiments confirmed a prior study in India that dietary animal protein could turn cancer on and off, depending on the level of protein.8  A liver toxin (aflatoxin) was used in rats and mice to injure the liver cells’ DNA.  A 20 percent animal protein diet allowed cancer to be turned on, i.e. it allowed the injured liver gene to express itself.  A 5 percent animal protein diet would turn it off. A range of 4-24% animal protein (in this case casein, the major animal protein in milk) was studied. See chart 3.6 from Chapter 3, Turning Off Cancer in the China Study by T. Colin Campbell, PhD and Thomas M. Campbell, MD.8  Foci of cancer did not start to develop until the diet contained about 10% animal protein. Beyond 10% the increases in dietary protein dramatically promoted cancer. Note the marked increase in cancer cells from 12-20 percent animal protein. The average American consumes 15% protein (mainly animal protein). These animal studies hint that our excessive animal protein consumption places us at risk.

   

 

In these laboratory experiments, it was clear that too much animal protein in nutrition could promote cancer. It is very interesting that in these same experiments plant protein in the form of soy and wheat protein, did not promote cancer growth even at the 20% level.


Although Dr. Campbell is pretty confidant of the applicability of these animal studies to human populations, as a scientist he understands the reluctance of his colleagues to agree without confirmation in humans.12 These types of animal experiments with carcinogens cannot be done in humans. Yet these rat and mice studies are extremely important in our understanding of mechanisms whereby nutrition can promote, stop, or reverse cancer.


Human studies by Dr. Dean Ornish and others in men with early prostate cancer take us to another level of scientific inquiry. While his holistic approach is not limited to plant based nutrition, it does show that lifestyle changes can not only work as well as drugs and surgery, “but often even better and the only side effects are good ones”13  Working in collaboration with Dr. Peter Carroll, the chairman of the Department of Urology at the University of California, San Francisco and with the Department of Urology at Sloan Kettering in New York city, Dr. Ornish and his team studied a group of men with early prostate cancer.14 The control group received no treatment and the experimental group underwent lifestyle intervention. The lifestyle intervention included a whole-foods, plant-based nutrition, exercise, and how we respond to stress (meditation, yoga, etc). The result shows that lifestyle intervention may slow or reverse the progression of early low grade prostate cancer. In addition, in the group that changed their lifestyle over 500 genes were changed, in effect turning on the genes that prevent disease and turning off the genes that promote cancers, such as the breast, prostate  and colon.15


Exciting new research about telomeres and genes is introducing us to another mechanism whereby nutrition can affect cancer and other diseases. Lifestyle changes that include a whole-foods, plant-based diet significantly increase telomerase, the enzyme responsible for maintaining telomere length.16 Telomeres are protective DNA-protein complexes or “caps” at the ends of chromosomes that house our genes. They are important cellular structures whose integrity is essential for maintaining the life of the cell.17 Dr. Ornish and Dr. Elizabeth Blackburn who won the Nobel Prize in Medicine in 2009 for her groundbreaking work on telomeres collaborated in this study.


The telomeres can wear down or get frayed. There is now clear evidence linking telomeres and their associated proteins to cancer, cardiovascular disease, and ageing.17,18 Increasing the cell’s concentration of telomerase is thought to lengthen the telomeres, thereby providing stability for the chromosomes that is associated with tissue renewal and disease prevention. This is the first time that any intervention, even drugs, has been shown to significantly increase telomerase.4


There is a very large body of studies, including world-wide observational and migration studies, linking the importance of nutrition in three common cancers-breast, prostate and large bowel (colon and rectal). A major observational study is now being done by the National Institutes of Health using the population comprising the American Association of Retired People.  A recent study published online in the Archives of Internal Medicine used data from two very large studies of men and women who filled out questionnaires about health and diet.5  Eating red meat was associated with a sharply increased risk of death from cancer and heart disease. A daily serving of processed meat carried an even bigger risk. Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health and the lead author of the study said in an interview: “I think the public health message is pretty straightforward. We should switch from a red meat-based diet to a plant-based diet with healthier protein choices.”6

               

It appears that nutrition can play a major role both in the prevention and treatment of cancer. There are probably a number of mechanisms or pathways by which this occurs. “There is enough evidence now that doctors should be discussing the option of pursuing dietary change as a potential path to cancer prevention and treatment.” T Colin Campbell  

 

 


 

Plant Based Nutrition (PBN):

  1. Introduction

  2. Coronary Artery Disease and PBN

  3. Cancer and PBN

  4. References & Websites