Recently I have noticed recipes specifying the type of cooking oil.  "2 T canola oil," "1 T cottonseed oil," that kind of thing.  Now we're not talking a specialty oil, like recipes which specify extra virgin olive oil, or oils with particular flavor like sesame or chili oil.  I'm talking about oils that ordinarily I would just lump under the category of "vegetable oil."

Luckily, we don't have to worry about trans fats in the cooking oil section.  Trans fats are found in palm oil and coconut oil, neither of which are for sale at my local grocery store, anyway.

I decided to do some research.  What I found is that there is no single answer.  (Why must life be so complicated?)

Olive oil: Still considered the healthiest oil all around, but it's so expensive!  And aside from olive oil being a poor choice for baked goods, it's ridiculous to use olive oil for every single cooking application.

Canola oil: Canola oil is high in monounsaturated fat (good). It also contains high levels of omega 3 fatty acids (good) which most American diets lack.  Chemically speaking, canola oil has the same profile as olive oil - but without the strong taste.  For all purpose cooking uses, unless you're looking for a specific health benefit that the other oils provide, canola oil is probably your best choice.

Despite the rantings of many kooky websites, canola oil does not contain toxins.  

Peanut oil: Like canola oil, peanut oil is high in monounsaturated fats.  It performs better at high temperatures than canola oil.  However, it's obviously not the right choice for people with peanut allergies.  (Think of your dinner guests before using peanut oil!)

Safflower oil: Although safflower oil is high in polyunsaturated fat (bad) it is also high in vitamin E (good).  However, it is furthermore high in omega 6 fatty acids, which are problematic. 

Omega 6 acids can be good for you, when taken in the right balance with omega 3 fatty acids.  Americans as a rule get too much omega 6, and not enough omega 3.  So safflower oil is probably not the best choice.  (I also found this guy, who believes that omega 6 fatty acids lead to homicide. Oooookay!)

Sunflower oil: Like safflower oil, sunflower oil is high in polyunsaturated fat (bad).  However, it lacks the vitamin E which safflower oil contains.  And it is also high in omega 6 fatty acids, which is problematic as we have seen.  It's probably best to pass on the sunflower oil, as well.

Vegetable oil: a lot of brand name oils are actually a blend of oils from various sources, primarily soybean.  For example, Wesson's "vegetable oil" is 100% soybean oil.  Soybean oil is high in omega 3 fatty acids (good) and vitamin E (good).  Soybean oil also includes a lot of polyunsaturated fats, which might increase your cancer risk.

Corn oil: Corn oil contains unsaturated fat (good).  However, although corn oil manufacturers claim that corn oil reduces the risk of heart disease, the FDA has found no solid evidence to prove this.  So take those claims with a big ol' grain of salt!