What causes cancer, and what contributes to cancer formation? These are two different concepts that overlap and influence each other.

A cause of cancer is a carcinogen. A contributor to cancer formation can be mutagenic but is context-driven by the strength and duration of exposure, genetic predisposition to cancer, and the collective burden of other environmental triggers. 

A known carcinogen such as ionizing radiation will almost always result in malignancy with sufficient exposure. A cancer contributor encourages cancer growth that was prompted by some other cause.

Animal foods get a bad rap in this regard. Someone with a bias against animal foods might read an observational study purporting a correlation between meat consumption and cancer incidence and conclude that eating meat causes cancer. There is far more nuance than what is suggested in observational research. Using red meat as an example:

• Red meat might contribute to colon cancer growth in someone who has smoked and been exposed to agricultural herbicides for decades.

• Red meat might contribute to cancer growth when part of a diet low in the amino acid glycine. Muscle meat is high in the amino acid methionine, a desired element of the metabolism of cancer cells. Glycine counterbalances excess methionine.

  
  

  

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• Red meat might strongly contribute to cancer formation when grilled at high heat, resulting in the formation of carcinogenic polycyclic aromatic hydrocarbons and heterocyclic amines.

In all these instances, red meat is not the overt carcinogen. I can appreciate the choice of a cancer patient to adopt a plant-based diet for a period of time (a form of fasting) to enhance detoxification; however, the argument to avoid red meat because it causes cancer is presumptuous. 

Context is king. Eating a small portion of minimally cooked or raw grass-fed red meat balanced with foods high in glycine, such as animal skin and bones (most notably in collagen-rich bone broth), and going for a brisk walk after the meal is a totally different scenario than overeating a large portion of chargrilled feedlot-sourced red meat along with a diet soft drink and highly processed sugary dessert before sitting on the couch and chain-smoking cigarettes.

It is critical to make this distinction because humans are not universal in their needs, dietary or otherwise. In one context, restricting meat might be an important strategy to holistically retard cancer growth. In another context, the nutrients in animal foods might be vital components to optimize immune function of a cancer patient.

Most importantly, we should wisely acknowledge and address cancer contributors without unscientific thinking or ideological fervor distracting us from identifying and remediating carcinogens.