It used to be, in certain cultures, butter was just what you had. You had a cow, you milked her, you skimmed off the cream and made butter. It was the fat you had around and you used it. And it tasted good! No one worried about nutrition facts or saturated fat or the differences between butter and other fats for cooking.
Then butter became evil, according to health experts. And they told everyone to stop eating butter, so they ate margarine instead. Of course, it turned out that margarine wasn't so nutritious either, so a lot of people have gone back to butter - after all, it tastes better, and it's more natural.
Other experts say that we should be using oils, like olive oil, or flaxseed oil (but don't cook with it!), or even coconut oil, which is supposed to be very good for you.
But you know what? Butter tastes good. Especially in desserts. And it doesn't even take much - but a cookie with some butter in it tastes a million times better than something made with a butter replacement. And I love olive oil, but not in a cookie.
Nutrition is such a complicated thing.
So I like to use butter in moderation. (Good nutrition is all about moderation.) For savoury things, a lot of the time I'll use half butter and half olive oil, which I think is a way to get the best of both worlds. And in baking I use butter but sometimes I'll use some oil, or some applesauce or banana and just less butter. Desserts are better with butter, so you know what? Just eat less, and enjoy it.
What do you think about butter and nutrition? What fats do you use to cook?