Shortening or vegetable oil combined with salt is a suitable substitution for margarine, according to allrecipes.com. Butter or a combination of lard and salt are also viable substitutes.
One cup of shortening with 1/2 teaspoon of salt can be used to replace 1 cup of margarine, as can 1 cup of salted butter. Seven-eighths cup of vegetable oil mixed with 1/2 teaspoon of salt also serves as a substitute, and the same proportions work for lard and salt. Unilever holds that the fats in margarine are healthy and help to maintain normal blood cholesterol levels. Margarine normally contains salt and cannot be used as a substitute for unsalted butter.