| The link between meat consumption and colorectal cancer has been shown to be almost entirely mediated by two primary factors: nitrosamines and transition metals. Nitrosamines are not naturally present in meat. They are produced when peptides (dietary protein) are heated a lot in the presence of oxygen. Nitrosamines are generally not produced when the protein is intimately mixed with large amounts of carbohydrates, because these act as antioxidants. So the line is "vegetable proteins do not generate nitrosamines", but if you were to extract those proteins into a meat-like product, common sense says that frying this like chicken will generate nitrosamines. The nitrosamines are just generated when organic nitrogen is oxidized to nitrogen dioxide, which reacts with peptides to generate nitrosamines. (Many vegetarian meat substitutes contain a lot more carbohydrate than real meat does. But there is an easy way to mix carbohydrates with your meat; that is left as an exercise to the reader.) (Also, the amino acids lysine and arginine generate more nitrosamines than other amino acids. These tend to be poorly represented in most plant proteins. They are also essential amino acids, and lysine in particular has been the object of serious investigation in the search for "complete" plant proteins.) Transition metals are naturally present in meat. The most important carcinogenic transition metals are iron and copper. Both iron and copper are carcinogenic. Both iron and copper are necessary nutrients. In fact, iron and copper are two of the most important nutrients available in meat which require some planning to incorporate into a vegetarian diet! In a very real sense, the same nutrients that would motivate you to eat meat are also the ones which cause it to be correlated with cancer. Red meat is a particularly dense source of iron, so of course it has the strongest correlation with colon cancer. (High iron titers in many vegetables report insoluble iron complexes which are neither nutritive nor carcinogenic. Iron in meat is highly soluble, nutritive and carcinogenic.) This is not surprising when you consider that cancer is made of the same cells that we are and have (mostly) the same biochemistry that we do. When vegetarians talk about meat causing cancer, they always try to make it sound like God is punishing us for eating animals. Nothing could be further from the case. But most importantly: the odds ratios are small. So I had a chicken sandwich for lunch. |