Friday, February 5, 2010

Food and cancer, a complex topic.

To all those making claims that all "cancer" is a preventable disease,

Shame on you. I am sorry to say that this is one myth floating around health-food grocery stores and the internet that is sorely, and dangerously mis-informed. I would refer you first to the textbook, The Biology of Cancer by Robert A. Weinberg to explore the incredible complexity of the nature of cancer. The first thing you need to understand is a theory called 'Multistep Tumorigenesis' (which I'll post about on another day).

The following comment was posted on the LiveStrong blog in response to a report from the Union Against Cancer (UICC) that states 40% of cancers could be prevented with vaccines and a healthy lifestyle:

"Sorry but this report is bogus . Vaccines are not the answer – they cause more problems than anything, as do anything we ingest which is not made from food. As far as the statistics, that number is way off. I would venture to say 100% of cancers can be prevented. That’s right, 100%. 1 0 0. 100% preventable, 100% curable (if caught early enough)."

My response to people who hold such a viewpoint:
1. Please don't ever talk to parents of anyone who has a child with cancer. Pediatric cancers are different, much different.

2. You are putting too much blame on people who, to absolutely no fault of their own, have ended up with various cancers. You need to educate yourself before you make such vast and appallingly incorrect generalities.

3. You need to read about tumor viruses and you need to get some facts regarding disease prevention and vaccines. Until you have done either, you should keep your dangerous and terribly mis-informed statements to yourself. Editors of the Livestrong blog, you should be ashamed to have published such statements.

There is no doubt that the environment (food, toxins, radiation etc) are involved in the incidences of some cancers. From Weinberg's text:

"Although the incidence of some cancers (e.g., some pediatric ones) is comparable worldwide, many vary dramatically by country and therefore cannot be due simply to a normal biologic process gone awry by chance. Differences in heredity or environment might well explain these differences; in fact, epidemiologic studies have shown that environment is the dominant determinant of the country-by-country variations in cancer incidence." It is also true that Seventy-Day Adevntists, whose religion discourages smoking, heavy drinking, and the consumption of meat, die from cancer at a rate that is only about half that of the general population.

The conclusion is inescapable: "the great majority of the commonly occurring cancers are caused by factors or agents that are external to the body, enter the body, and somehow attack and corrupt its tissues". These agents are often viruses. Vaccines help prevent viral infections (e.g., Smallpox eradication and huge decreases in polio). Environmental toxins (aflatoxin B2, sterigmatocystin, benzo[a]pyrene, 4-aminobiophenyl, 2-naphthylamine, etc) can be mutagenic and therefore carcinogenic. Radiation is no doubt, a culprit. Food is another, very complex matter. From Weinberg:

"A diverse set of discoveries led to the model, which remains unproven in many of its aspects to this day, that a significant proportion of human cancer is attributed directly to the consumption of foodstuffs that are mutagenic and hence carcinogenic. Included among these foodstuffs is, for example, red meat, which upon cooking at high temperatures generates compounds such as heterocyclic amines, which are potently mutagenic. The difficulties in proving this model derive from several sources. Each of the plant and animal foodstuffs in our diets is composed of thousands of diverse chemical species present in vastly differing concentrations. Almost all of these compounds undergo metabolic conversions once they are inside our bodies, first in the GI tract and often thereafter in the liver. Accordingly, the number of distinct chemical species that are introduced into our bodies is incalculable. Each of these introduced compounds, once it is present in the body, may then be concentrated in some cells or quickly metabolized and excreted. This creates a further dimension of complexity."

"In sum, the ability to relate the mutagenicity of foodstuffs to actual rates of mutagenesis and carcinogenesis in the human body is far beyond our reach at the present-a problem of intractable complexity".

Should we then ignore food because we can't define the exact culprits? I would argue no. I believe Michael Pollan and his book "In defense of food" best summarizes the health consequences of a modern industrialized diet as well as modern 'nutritionism' as we know it. In my view, one should ignore much of what nutritional science tells us (macronutrient obsessions) and practice the following:
-Don’t eat things that your great-grandmother wouldn’t recognize.
-Avoid anything that trumpets the word “healthy.”
-Be as vitamin-conscious as the person who takes supplements, but don’t actually take them.
-"Eat food. Not too much. Mostly plants.”

1 comment:

Lucas said...

Very interesting piece, Dan. Well written, too!