Flaxseed oil              610 mg                   2510 mg

Safflower                 640 mg                        0 mg

Canola oil                 920 mg                    420 mg

Corn                      2630 mg                      80 mg

Even beef provides some omega 3's.  A 3 ounce serving of sirloin steak provides 200 mg omega 6 and 70 mg omega 3.

(Source - I obtained the numbers above from ESHA Food Processor Software.)

Olive oil is 85% oleic acid and has little effect the omega 6 to omega 3 ratio.  I like olive oil for this reason, but it can be argued that selecting oil that contributes omega 3's to your diet is more beneficial, even though you also gain omega 6's. 

Dr. Dean Ornish claims that olive oil reduces blood flow by 31%.  What he is referring to is reduced brachial artery (the main artery in the upper arm) blood flow, not coronary artery blood flow.  For this reason, it's possible that the monounsaturated fat of olive oil is not the best choice to protect against arterial fat deposits when compared to other fats that offer more omega 3's.

However, I'm not changing my recommendations yet.  I still encourage you to switch from standard vegetable oil or shortening to a more heart healthy cooking oil, such as olive or canola oil.  This alone isn't going to give you dramatic heart health improvements.  You need fish in your diet at least twice a week, select a supplement that will provide you at least 1000 mg of omega 3 fatty acids daily (choose a good source of DHA and EPA), use ground flaxseed when appropriate in your meal preparation, and select heart healthy nuts (such as walnuts) once in a while for a snack.

Be sure to sign up for the free e-course How to Lower Cholesterol in 8 Simple Steps by dietitian Lisa Nelson.