The fatty acids that the body cannot produce are called essential fatty acids.

Here's why:

* Essential Nutrients: Essential nutrients are substances the body needs but cannot make on its own. They must be obtained through diet.

* Role of Fatty Acids: Fatty acids are important components of cell membranes, hormones, and other vital molecules.

* Two Essential Fatty Acids: There are two main essential fatty acids:

* Alpha-linolenic acid (ALA): An omega-3 fatty acid found in flaxseed oil, walnuts, and leafy green vegetables.

* Linoleic acid (LA): An omega-6 fatty acid found in vegetable oils like sunflower and corn oil.

The body can convert ALA into other omega-3 fatty acids like EPA and DHA, and it can convert LA into other omega-6 fatty acids. However, it cannot convert omega-3s to omega-6s or vice versa.