The good news is, fruits and vegetables are still really good for you!  The bad news is that they don't actually prevent cancer - not to the extent that we recently thought.  NPR has an interesting story on how, in the 1990s, nutrition experts "thought the five-a-day regimen would reduce overall cancer risk by as much as 50 to 70 percent."  When in reality, it turns out to only reduce your risk by about four percent.

This complete reversal only strengthens the assertions in Michael Pollan's The Omnivore's Dilemma, where he insists (with a great deal of research and logic to back him up) that our grasp of nutritional science is weak at best.  No less an authority than the World Health Organization (WHO) and the National Cancer Institute both jumped onto the "fruits and veggies prevent cancer" bandwagon with both feet!

Perhaps the most surprising thing about this is that it seems so logical.  Fruits and vegetables are good for you.  Is it any surprise that they would prevent cancer?  

One flaw in the studies, according to the chairman of nutrition at the Harvard School of Public Health, is that they are not drawing on a representative sample of the public.  Apparently the participants in the studies were unusually healthy people to begin with, which is why they were willing to join a study where you have to eat five servings of fruits and vegetables a day.

Cancer is a multi-dimensional illness, it isn't as simple as "people who inhaled this virus got sick."  A lot of factors go into the equation, with either "cancer" or "no cancer" kicked out at the far end.  Your overall lifestyle pattern has a lot to do with whether or not you get cancer, and the healthier your lifestyle, the less likely you are to get cancer.  That's the conclusions of the Harvard critic, anyway.

However, this doesn't mean you should switch to an all-McDonald's diet!  Fresh fruits and vegetables have a number of health benefits, even if "prevents cancer" isn't one of them.  It lowers your risk of heart disease and stroke by 28%, for one thing.  And there is a lot of evidence that specific fruits and vegetables prevent specific cancers (NPR cites the example of the lycopene in tomatoes preventing prostate cancer, which is a very well-researched connection).  

Another point this study touches on is that the benefits to fruit and vegetables are also "exclusionary."  Meaning that if you're eating an apple and a big salad for lunch, you aren't eating a Triple Angus Burger with cheese and bacon.  In other words, what you DON'T eat can be just as important as what you DO eat!

There are a thousand reasons that eating fresh fruits and vegetables is good for you.  That's just common sense.  If "prevents cancer" isn't among them, then so what?  Should our government drop its recommendation that we eat five servings of produce a day?  I really don't think so.  (Even if, as on the latest episode of "Jamie Oliver's Food Revolution," we learn that ketchup and french fries both count as a vegetable.)

Creative Commons-licensed image courtesy of Flickr user Mr Noded