I've finally figured out why I only got one hour of nutrition training in med school. It couldn't have been that my teachers believed nutrition isn't important because only morons would deny the value of a good diet, and people who run medical schools surely are not...well, let's not go in that direction.
No, the reason they didn't teach us more about nutrition is, I'm sure, that they couldn't agree on how to interpret most nutrition information, and the scary thing is they probably still can't.
I mean, get a load of some current nutrition news. In several excellent studies,
higher fiber intake did not lower the risk of developing colon cancer (or pre-malignant
changes) in both people at high and average risk for this malignancy. These
findings turned years of advice to eat more fiber as a cancer-preventive on
its end, although you should not abandon your fruits, veggies, and fiber just
yet because higher fiber intake is still linked to lower risk of developing
heart disease and diabetes.
If you want to prevent breast cancer, though, you better not rely on fruits and veggies, because in another huge study, women who ate more fruits and veggies did not lower their risks of breast cancer, again contradicting common medical opinion.
And you know how some experts believe that dairy products are the devil's own food? Well, in another study, people who drank 4 or more glasses of low-fat milk a day had a significantly lower risk of heart disease than those who avoid milk.
And then there's green tea, which has, for years, been promoted as a cancer preventive, in large part because of the claim that drinking lots of green tea helps the Japanese lower their risk of stomach cancer, a particularly common cancer in Japan. When investigators recently took a look at this connection, however, they declared green tea useless in preventing stomach cancer, although they also said that there might be other health benefits from green tea, like, for example, how mellow it makes you.
So why is nutrition information hard to pin down? Because it's difficult to isolate one aspect of diet (or behavior) as the only variable to explain differences among people. Thus, those who eat a healthier diet are also often more educated, exercise more, and so on, and it's extremely hard to figure out which of those many factors is the most important in determining a particular measure of their better health.
But don't despair. There are a few things no one can deny - a kiss is just
a kiss, a sigh is nothing...oops! I mean, we know, for example, that lots of
calcium started early in life helps prevent osteoporosis, that (as stated earlier)
a diet high in fiber, fruits, and veggies is correlated with lower risks of
diabetes and cardiovascular disease, while a diet high in saturated fat is linked
to more cardiovascular disease, and so on.
In the end, though, good nutrition is not a series of equations, but rather one simple axiom - a good diet is a varied, well-balanced diet moderate in most things, but one that also stresses fruit, veggies, fish, and fiber over meat and fats - and you know, I must hand it to my med school teachers in retrospect because that really doesn't take more than an hour to teach.