Saturated Fats
Saturated fats come from meats, dairy products, egg yolks, fish, coconut oil, and palm oil. Saturated fats are very stable and very resistant to rancidity. While you should be cautious of eating too many of these fats, healthy natural versions are an important component of a well-rounded diet. One example of how important these fats are is their use in the cell membrane structure. An example of a healthy saturated fat is conjugated linoleic acid. This fatty acid has been shown to be very beneficial to health in a variety of ways.
Which saturated fats are harmful and why?
Natural saturated fats found in nature--such as those in coconut or palm oil--are all right to eat in moderation. In fact, new evidence shows that these sources of fats are beneficial and helpful in a well-rounded diet. The saturated fats show up in two forms: “cis” fatty acids and “trans” fatty acids. The “cis” form is found in nature, and is the healthy form of saturated fat. Because the “cis” form has two hydrogen atoms on one side, other chemicals and enzymes can bind to it, thus allowing the mollecule to become useful in digestion and metabolism.
The "trans" form is found minimally in nature, and is primarily the creation of industry through the process of hydrogenation. In “trans” fats, the hydrogen atoms are on opposite sides of the mollecule, making it much more difficult for other chemicals and enzymes to bind to it. This is why these unnatural fats remain primarily undigested. Over time, these undigested “trans” fats build up and cause harm.
Additional reading:
An excellent explanation of this difference can be found at Trans fat, the real culprit of western ill-health.