Saturday, June 22, 2013

Another case of chemophobia - Processed meats are "too dangerous for human consumption".

Recently, a friend on Facebook alerted me to an article claiming that:
"The World Cancer Research Fund (WCRF) has completed a detailed review of more than 7,000 clinical studies covering links between diet and cancer. Bottom line: Processed meats are too dangerous for human consumption. Consumers should stop buying and eating all processed meat products for the rest of their lives."
That is a pretty serious claim. Processed meats are pretty common: Hot dogs, sandwich meats, bacon . . . WAIT. Bacon? Are you serious? The World Cancer Research Fund has said that bacon, even in small amounts, is dangerous for human consumption? Please, say it isn't so!

Or, if you won't say it isn't so I will . . . it isn't so. The World Cancer Research Fund said no such thing. They even responded to this article on their own website, saying:
"The articles talking about processed meat being 'too dangerous for human consumption' are unhelpful and scaremongering."
The WCRF also pointed out that the "recent review" being talked about was performed in 2007. A more recent meta-analysis shows that while the question of red meat consumption is very much resolved (eating >120 grams of red meat per day raises your risk of cancer by 13%), the question of processed meats is not as clear. Although review of the available literature shows that 50 grams daily of processed meats raises your risk for colorectal cancers by 19%, the p-value, which is a measure of the significance of an effect (the lower the value the more significant) was pretty high. The p-value was 0.46. Usually you want to see a value <0.05. The red meat p-value was <0.001, so ya, don't eat red meat every day.

So, to recap that last paragraph (if I lost you in the numbers): Don't eat red meat every day, and avoid processed foods. But what does that even mean? The WCRF uses the same language, and it's frustratingly ambiguous. Does "avoid" mean (as the first article suggests) that all processed foods are "too dangerous for human consumption", or does it mean that you should just try to eat less? In the WCRF's response to the "scaremongering" article they say that there would be 4000 fewer cases of cancer if people ate less than 70 grams of processed meat per week [citation needed]. However, they stress that avoid does not mean completely remove from your diet. Instead, they advocate a balance. Again, to them this means less than 70 grams per week, while the recent meta-analysis I found said less than 50 grams daily. That's a little less than two hot dogs per day or one-quarter of a large sandwich meat container.

And let's face it. If you're eating more than 14 hot dogs every week I think you already know you're not eating healthy.

Sodium Nitrite
One chemical that is specifically pointed out in this debate is sodium nitrite (NaNO2). I'll admit, this is not a very welcoming image to see on the chemical's warning label:

File:Hazard T.svg

But, we can't let that be the end of our research. What is sodium nitrite, and should you completely avoid it?

Let's answer the cancer question first:
"The National Academy of Sciences, the American Cancer Society and the National Research Council all agree that there's no proof of cancer risk from consuming sodium nitrite."
Now, I agree that the source of this statement isn't the strongest I could provide, but the conclusions agree with the Material Safety & Data Sheet for sodium nitrite, which place it in the "unknown" column for cancer, so I'm using it. Sodium nitrite has not been shown to cause cancer. Let's move on to what sodium nitrite is, and where it's found.

Sodium nitrite is used as a preservative. Now, I hate that I have to explain this, but that doesn't mean that it makes your food dangerous. That's a common thought. Preservatives are bad. Always. That's a statement that's not supported by science though. In fact preservatives are used to . . . preserve your food. Specifically, sodium nitrite keeps botulinum, one of the most deadly of all toxins, from growing in your food. To put this in perspective, botulinum toxin is fatal at a dose of about 0.000000002 grams per kilogram of body weight. If given a choice between botulinum toxin and sodium nitrite I choose sodium nitrite every time.

But, maybe that's a false choice. After all we could just eat foods that don't require chemical preservatives, right? Let's say, for example, spinach, carrots, and celery. These fresh vegetables must be an excellent substitution for foods high in preservatives, right?

Well, as far as the sodium nitrite content goes, not really. Fresh vegetables contain sodium nitrate (NaNO3), which your body converts to sodium nitrite (NaNO2). So if you are worried specifically about sodium nitrite in your food then you need to stay away from a lot more than just processed meats (Please note: I am not saying that processed meats are as healthy as fresh vegetables. I'm saying they both contain similar amounts of nitrates/nitrites).

So should I change my diet?
Frankly, everything can give you cancer - it just depends on who you listen to. Here is a pretty extensive list of things that have been reported (by The Daily Mail) to cause cancer. Some of the entries are ridiculous, some are contradictory, and some are just plain wrong. The important thing to remember is the dose determines the poison. That is, just because something in large amounts will increase your risk of cancer does not mean that small, controlled, balanced portions of that same thing will give you any problems at all.

Should you change your diet? I don't know. Do you eat more than 50 grams of processed meats every day? If so you might want to change that. As for me, I already eat less than the recommended amount of processed meats, so I'll enjoy a hot dog every now and then or some bacon when I get the chance.