TJ actually saw this article and it was very interesting. We had a lengthy discussion about it last night talking about the merits and shortcomings of the study. Here is my view upon the article:
Something important to note that protein intake elevates the level of IGF-1 (insulin-like growth factor 1) in your body - this is the hormone that is "linked to cancer" that you stated above - people throw around "such and such is linked to cancer" around too liberally. IGF-1 is present in proteins like cow's milk/animal meat and is an important part of growth in children and in maintaining strength within the elderly. IGF-1 is a stimulator of cell growth and proliferation, and an inhibitor of cell death. Now, with these things being said, the study claims that if you have cancer cells present in your body, IGF-1 will increase the growth and inhibit the death of these cancer cells. They are saying that IGF-1 is essentially fertilizer, and instead of fertilizing your beautiful flowers and plants (your regular cells), it could be fertilizing weeds (cancer cells).
While this statement is valid if there are in fact cancer cells in your body, there are quite a number of factors that the study does not take into account. The study does not mention the source of the animal proteins that it uses as a variable. Is the meat conventionally grown? Organic? Free range? Was it drained of fat? TJ and I are very careful to buy organic/free and drain the fat if not - where toxins are stored within meats. Does the level of toxins in the meat play a role in the amount of contaminants in your body and your susceptibility to cancerous cells? The initial study does not make this claim.
Another study that is linked within the article bases the merits of its article upon participants who ingested hot dogs, cold cuts, and bacon. I know that if any individual were to subsist on a diet of processed meats, they would surely have negative health effects. Were these deli meats and bacon nitrate, chemical, and preservative-free like the ones I choose to purchase? I would assume no.
Here is quote from a linked article: http://www.livescience.com/18996-red-meat-premature-death.html "Conversely, replacing one serving of red meat with one serving of a healthy protein source was associated with a lower mortality risk: 19 percent lower when the meat was replaced with nuts; 14 percent for poultry; ... "
At home, we eat plenty of other protein sources in place of red meat. We eat ground turkey with organic beef. We eat organic chicken sausages free of chemicals and preservatives. I think the key here is that you are eating a diversified diet with plenty of sources of protein as well as vegetable intake. I eat a 2 cups of vegetables at lunch and 2-3 cups with dinner. TJ and I go through a Costco bag of broccoli in 4 days - I know, gassy! I eat peas, green beans, spinach, nuts, bananas, and plenty of other wonderful fruits and vegetables that provide my body with abundant phyto and micronutrients. This study does not take into account the fiber intake of these individuals. Are the individuals in the study eating processed red meat and a ton of processed foods? Then surely, those individuals were already susceptible to cancer, based upon their other daily habits and life choices ... and let's be honest ... the typical American diet is terrible.
Another topic the study does not touch on is how IGF-1 prioritizes its use within the body. With the rigorous strength and aerobic training that I undertake for hours a week (roughly 1-2 hours per day for 6 days a week), my body needs protein in order to stimulate IGF-1 to help muscle repair and synthesis. Does IGF-1 get sent to the areas of need in the body (aka the muscles) and then it is used up so that no extra IGF-1 goes towards malicious (cancerous) cells?
It is generally stated in the exercise science community that for general body maintenance, a sedentary individual needs to consume roughly 0.8g of protein per kg of body weight. Now this intake increases to 1.2-1.4g per kg for endurance based athletes, and can increase to 1.4-1.8g per kg for strength based athletes. At 56kg, I would need 72-74g of protein based upon the endurance guideline, and 74-100g based upon the strength guideline - well above a sedentary person at my weight of 44g of protein a day. (That's not even two chicken breasts!) This leads me to believe that IGF-1 in cases of non-sedentary individuals goes towards essential recovery, muscle repair, and growth in active individuals, therefore contributing less to potential carcinogens.
Articles like this are always great because they make you rethink the current habits you have in your life. I am not trying to devalue the merits of this article, but simply stating different variables that decrease the applicability to my own life. I eat a wide variety of foods in a daily basis: ground beef, tomatoes, ground turkey, onions, eggs, bananas, almond butter, chicken, green beans, peas, pork, potatoes, broccoli, dark chocolate, green tea, water, lemons, etc. I easily eat all of these foods in one day in small amounts and mixtures. I exercise for 1-2 hours 6 days a week that includes necessary muscle repair and growth during my rest and recovery, which includes my sleep and diet. I also choose clean sources of these foods - I purchase organic vegetables, meats, and fruits. I have eliminated almost all chemicals and preservatives in my diet - anything that is unnatural and unrecognizable in nature. I feel that I live a healthy lifestyle and have a great connection with where my food comes from and where it's going, preparing each of my own meals. I live a very balanced lifestyle and I focus very much on keeping myself healthy for years to come :)