Eat your veggies.
That's probably still a good tip.
Only drink skim or lowfat milk. Go organic.
Woops. Not so fast.
The world of nutrition changes its mind every few years. Just about the time you get used to loving kale, some study is going to show that it's worthless and low in nutrients.
Back when I was about 25, oatmeal was the big thing. "Eat lots of oatmeal. It's prevents everything!"
Turns out that yeah, not so much.
Here's a great article from one of my favorite websites, parents.com.