Degree of Saturation of Fat

Medical research shows a correlation exists between dietary fat intake and heart and circulatory system problems. Additionally, some dietary fats have greater adverse effects on the human body than others. In general, the greater the degree of saturation of a fat, the greater its undesirable effects.

How do liquid-state dietary fats (plant oils) compare to solid-state dietary fats (animal fats) in terms of degree of saturation? Generally, plant oils are less saturated than animal fats, although coconut oil is an exception to the rule.

A measure of the degree of saturation of a fat (solid or liquid) is given by its iodine number, that is, by the number of grams of iodine that react with 100g of fat. The higher the iodine number, the lower the degree of saturation (a desirable situation in terms of diet).

Iodine numbers of selected solid and liquid fats are as follows:

coconut oil 8-10
butter 25-40
beef tallow 30-45
lard 45-70
olive oil 75-95
peanut oil 85-100
cottonseed oil 100-117
corn oil 115-130
canola oil 125-135
soybean oil 125-140
safflower oil 130-140
sunflower oil 130-145

[source: Chemical Principles by H. Stephen Stoker]