“Statistics are like bikinis.  What they reveal is suggestive, but what they conceal is vital.”  -Aaron Levenstein

I am a dedicated carnivore. Vegetables are cute and all and make the plate look real pretty, but I see no need for them beyond decoration. Potatoes are a bit like Styrofoam packing peanuts – they serve as good filler. But the meat is the essence of any meal that graces A Free Man’s table. In my opinion, Vegetarianism resides in the same neighborhood as other deviant beliefs like Republicanism and Fundamental Religiosity – I recognize that it exists, but have no interest in visiting.*

So, you may imagine that I followed the latest flurry of  “RED MEAT KILLS YOU” headlines with some alarm. After all, in my late 30’s, I’m trying to live a relatively healthy lifestyle. I’ve quit smoking. Again. I don’t do drugs or participate in other risky behaviors. I’m a Dad, I want to be healthy as my kids grow up.

But my response was more annoyance than alarm. I have very few unhealthy pleasures these days – a fat rare steak is one of them. Now I’m being told I can’t have that?

Bastards.

But then I remembered – I’m a scientist. I happen to know that the lay press is painfully unqualified to report scientific results in most cases. I have access to the primary literature. Let’s take a look at what these killjoys have come up with this time.

Unbiased observation, that’s what I’m all about.

The study, published in Archives of Internal Medicine by a group of researchers at the National Cancer Institute, looked at the levels of red meat, ‘white’ meat and processed meat consumption as risk factors for death. They used a cohort of over 500,000 volunteers between 50  and 71 years of age. The volunteers were men and women from six American states who agreed to fill out a food diary of their typical consumption over the preceding 12 months. When one of the volunteers died, they were placed into a group based on the amount of red, white or processed meat that they consumed. The researchers were asking whether or not high intake of different types of meat increased the risk of  death in general or death by cardiovascular disease or cancer specifically.

The researchers compile the questionnaire data and then get out the statistics software. If there is one thing that scientists can use to befuddle the general public – and often other scientists – it’s statistics. As it has been said, facts are stubborn things, but statistics are more pliable. The NCI researchers rely on something called Cox proportional hazards regression models to estimate the relative risk of, in this case, dietary behavior.

Using the statistical analysis, the group reports that ‘red and processed meat intakes were associated with modest increases in total mortality, cancer mortality, and cardiovascular disease mortality’, a result that inspired world-wide banner headlines at the end of last month. If you look a bit closer at their data, however, things aren’t so cut and dried.

The biggest issue is that this is a statistical association. In their, admittedly very large, sample population there is a slight association between a higher level of red meat in the diet and mortality. There is no evidence, and the group makes no claim, that eating red meat causes early death, cancer or heart disease.  The researchers haven’t attempted to determine a biological cause for their findings. Therefore, a causal link between red meat and cancer or heart disease has not been established in this study or in any previous work for that matter. Despite what you may have read in the newspaper or seen on the TV, this report does not provide a shred of evidence that eating red meat causes cancer.

I’m not a statistician – thank goodness. I’ve had a couple of stats classes, both of which served to confuse me more than anything else, so I’m ill equipped to quibble with their data. That’s never stopped me before, however, and it shan’t stop me now.

The researchers state that they adjusted for other factors that may affect their results including smoking, physical activity, age, education, marital status, family history of cancer, race, body mass index and many other factors. However, the data that they present in support of the hypothesis that a high intake of red meat increases the risk of mortality includes variation in these factors. For example, they state that “subjects who consumed more red-meat tended to be married…white…more likely a current smoker, have a higher body mass index, and have a higher daily intake of energy, total fat and saturated fat, and they tended to have lower education and physical activity levels”. In other words, in this study, people who eat a lot of red meat tend to be fat, lazy, white, smokers. And they had an overall increased risk of cancer and cardiovascular disease? Really?

More indicative of a design flaw, however, is the result that in addition to a higher risk of heart disease and cancer, men who eat a lot of red meat had “an increased risk associated with death from injuries”. Basically, the group classified as highest consumers of red meat had an increased risk of death due to all causes tested. At this point, I realized that their analysis was skewed – that there are inherent errors in study design. Again, I’m not a statistician, but I am a biologist and this category ‘death from injuries’ by all common sense should have been equal across all of their groups. The fact that one of the groups shows an increased risk indicates to me either that this group takes part in riskier activities in general (and the data hasn’t been properly normalized) or that the model is, in scientific terms, fucked. Either way, I’m skeptical of the results.

The take home message? Take from it what you will. This isn’t the first study to suggest that there may be a link between red meat and some types of cancer and cardiovascular disease. They tend, like this one, to be ambiguous.

Me, I’m going to fire up the grill.

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*I’ve always said that I’ll respect Boy Z’s decisions as he grows up. I’ll love him if he comes home one day and tells me that he’s a transgender, royalist, sheep shagger. He’s still my son. But if he ever comes home claiming that he’s a vegetarian then he’s out of the family.

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This track by Jim Lauderdale comes from the excellent three disc compilation ‘Song of America‘. It features covers of traditional American songs by contemporary artists and is available from eMusic.

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