Thursday, November 01, 2007

On Red Meat, Alcohol and Deli Cuts

Several articles have come out telling people not to eat much red meat or any smoked meats and to go easy on the booze. That's the way to avoid cancers of various sorts. Add to that the recommendation that you should be as lean as possible without being underweight (and how do we know where that point is?), and the stage is set for another go-around of the Great Health Discussion, having to do with behavior, morals and will-power, and the whole question of how to live forever. Note also that one of the linked articles begins by stating:

Many kinds of cancer could be prevented with simple lifestyle choices, says a comprehensive new report, which recommends keeping a lean body weight, limiting red meat consumption and ditching processed foods like bacon, hot dogs and luncheon meats except for the odd special occasion.

Simple? Anyone who has studied lifestyle changes knows that the process is anything but simple. It's painful, difficult and often fails.

Let me immediately state that I'm all for studies like the ones that were condensed in these recommendations. Information is power and it is excellent that we can all learn which foods and beverages are best for us. But I find that whenever one of these studies comes out the first reaction is an odd mixture of fear and moralizing. I'm old enough to remember the recommendations that nobody should eat salt and no more than one egg a week. Those recommendations are no longer offered to the general population, and that serves as a good reminder to take all and any recommendations with a certain grain of salt.

For we will indeed not live forever. This doesn't mean that cutting down on read meat consumption or drinking wouldn't be a good idea. It most likely is. What it does mean is that future studies could refine those initial findings or alter them. Here is why:

The studies reviewed in this most recent summary are not done in laboratories. They are done out there, in reality, where people who eat red meat might also eat a diet in general higher in fats and lower in vegetables, say. Whether the increased cancer risk studies find is linked to red meat itself or something else that is correlated with red meat consumption (such as the examples I gave) is not always clear. Doing observation studies of the sort these are is expensive and time-consuming as it is, and trying to control for every single possible cause of cancer is impossible.

Note also that these studies are not telling us that all people who eat smoked meats and drink a lot will die of cancer young or that all people who eschew those comestibles will live to a ripe old age. People die of many different causes, for one thing, and the cancer risks these studies measure are not what first comes to mind when you read the articles (that "first" appears to be a general fear reaction and the determination to avoid all red meats from now on or to ignore studies like these because they are too apocalyptic).

To give you an example of what studies of this type might find, let's make up some numbers. Suppose that we find that people who eat a diet rich in red meats get colorectal cancer at the rate of 66 cases per 100,000. Suppose, also that we find the same rate to be 60 cases per 100,000 among those who don't eat red meats at all. This is an increased risk of 10% in the chances of getting the cancer, assuming that the prevalence rates can be applied to a particular individual. Thus, the recommendation to avoid red meats might reduce that person's odds of colorectal cancer by 10%.

I made up those numbers, but the actual risk numbers for many types of cancers are not that different, and this is important to remember. To keep things in proportion.