The National Post, among others, sounded the alarm yesterday after a study linked high-protein diets to the same cancer risks you might see from smoking. We’re advocates of a high-protein diet for almost all our members so we decided to break down some of the details and see if anyone needs to hit the panic button.
First of all the study noted a two to fourfold increase in mortality. The expected risk for lung cancer from smoking is twentyfold. This doesn’t mean we can discount the study, just the alarmist headline.
Next we have to separate the epidemiological study from the mouse study. On the human side, exercise was not tracked. This is important for two fundamental reasons. First, protein is more useful as a dietary intervention for decreased protein synthesis (the short-term result of resistance training) than it is for sedentary folks. Second, people who exercise tend to make better protein choices (less processed meat, less smoked meat and less meat in cans, jars and tins). It is probably not useful to view a diet of grass-fed beef and quality legumes in the same way as one made up of Spam and Velveeta. In short, a lot of people eating high-protein diets eat poor quality protein and probably aren’t exactly drowning in vegetables either.
From the mouse study we can determine that it’s definitely bad to be a mouse with an implanted tumour on a high-protein diet. Mice typically eat very high carbohydrate diets, by the way. The association with IGF-1 (Insulin-like growth factor 1) does correlate with meat and does predict overall mortality. However, it doesn’t cause tumours – it makes them grow. That probably means that mice (and possibly humans) with tumours should adjust diet to minimize IGF-1.
That’s about it. If you’re under 50, exercise, and eat wisely (or any one of those things), this study cannot be applied to you.
If you’d like a more in-depth analysis, our pals at Examine.com have put together a great article here: http://examine.com/blog/high-protein-diets-linked-to-cancer-should-you-be-concerned/.
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