How many types of essential fatty acids are there?

There are two families of essential fatty acids, omega-3 and omega-6 fatty acids. The number 3 or 6 refers to the position of the first double bond, counting from the non-acid end. Both omega-3 and omega-6 fatty acids are converted into a wide range of physiological compounds necessary for health. Examples include: the control of inflammation; hair, nail and skin quality; and cell membrane function.