Some shellfish is moderately high in cholesterol, but also contains some omega-3 fat, so shellfish can be included occasionally in a diet to lower blood cholesterol levels. Foods that contain mostly monounsaturated fats are canola oil, olive oil, peanut oil, and the fat in nuts and avocados. Margarine made from partially hydrogenated vegetable oil will have less unsaturated fat than the original vegetable oil before the hardening process. If you want to get more unsaturated fat in your margarine, buy margarine that lists liquid oil as the first ingredient. Soft and squeeze margarines are usually more unsaturated than hard margarines.
Oils are even more unsaturated than margarine.
This stands for Polyunsaturated to Saturated fat. The higher the ratio, the better for lowering saturated fats in the diet. Since this ratio is not usually given on the package label, you can check the label for grams of saturated fat. The lower the better. Adding oils to the diet has become almost an obsession for some people.