Fats are organic molecules made up of carbon and hydrogen elements joined together in long groups called hydrocarbons. Fats make major contributions to sexual hormones and reproductive functions as well as its responsibility in lowering cortisol - which is a hormone that increases in heavily stressful situations.
A fat in it's most simplest form is what's called a fatty acid. The fatty acid chain consist of links of carbon atoms with a carboxylic group on one end (C-O-O-H) and a methyl group at the other (CH3). Whatever hangs off of the carbon chain stem in the center is what determines the kind of fat it is. Fatty acids comprise together to make triglycerides, which as the name implies, is just 3 fatty acids linked together with a glycerol molecule. Triglycerides are the major source of fat found in the diet and on the body. Let's look a little deeper:
Categorically, there are 2 different general kinds of fatty acids; Saturated fats, and Unsaturated fats, and within each of these two different categories, you also have different subcategories of fats that fall under each category.
Saturated fat (SFA) - It is named as such because no other hydrogen atoms can fit onto the basic carbon structure found in fats because there is not enough room to hang another hydrogen atom-it won't fit because all of the carbon chains are already 'saturated' with (shortening, and animal fats). These are usually solid at room temperature because of the extra hydrogen atoms attached to them.
Think of it this way, the name of the fat simply describes how much hydrogen are attached to the carbon atom chain (the core of a fatty acid chain). The 'saturation' of all the carbon atoms is in the name.
Unsaturated fats - you can think of these with less hydrogen atoms attached to it, which would make them less solid at room temperature. There are two different kinds of unsaturated fats:
Omega 3's and Omega 6's
Essential and Non-Essential Fatty Acids
Essential fatty acids (EFA's) are fats that the body cannot manufacture on it's own and must be obtained from outside dietary resources. EFA's include the Omega 3's and Omega 6's. There are quite a few fatty acids but specifically linoleic acid (found in unsaturated Omega 6's) and alpha-linolenic acid (found in unsaturated Omega 3's) are the most important because they lend a hand in helping to produce the other fatty acids. In other words, as long as you have quality resources of linoleic and alpha linolenic acids in your diet, your healthy body will produce the others that are needed.
Non-Essential Fatty Acids (non-EFA's) are named such because you body does not need them for survival.
Hydrogenation is the process of taking an oil and forcing hydrogen atoms onto a carbon atom chain. This end product of this process is called a trans fat. So in effect this is increasing the saturation. If we know that saturation is what makes that fat bad for you, then we know that hydrogenated fats are the worst form of fat for you there is. It is also a manufactured fat as it does not occur naturally. Hydrogenation is used to increase the shelf life, taste, texture and stability of the end product in most pre-packaged products and you will find this in things like cookies, margarines, frozen pizzas, donuts, muffins, chicken nuggets, chips and usually store-bought baked goods. If you remember, there once was a time where you would look at the packaging of certain products and it would boast that there were "0 trans fats!" on the label.
Please be advised, however, that the FDA has approved a 0.5g per serving allowance. They are still allowed to add to their product labeling that the product is trans free. That may seem like a minuscule amount, but if you are eating more than one serving of the product in addition to other products, as many of us often do, that tends to add up pretty quickly.
It has been discovered that saturated and trans fats increase the risk for cardiovascular disease (CVD). SFA's, and trans fats cause heart disease by clinging to your arteries easily causing blockages to the heart, which results in less blood flow to and through the heart. In 2006 the FDA required that companies list the grams of fat that a food contains on the Nutrition Facts label.
Butter is rich in short and medium chain fatty acids, including even small amounts of lauric acid. It is rich in antioxidants as well, in the form of beta carotene, vitamin E, and selenium. It is one of the best sources of vitamin A. Because living grass is richer in vitamins E, A, and beta-carotene than stored hay or standard dairy diets, butter from dairy cows grazing on fresh pasture is also richer in these important nutrients. The naturally golden color of grass-fed butter is a clear indication of its superior nutritional value. Grass fed is always a better choice from animals who are made to digest the food they were meant to eat. In this case cows should be grazing on grass, not grains, and so therefore produce a better, healthier butter (or meat).
Searles, SK et al, “Vitamin E, Vitamin A, and Carotene Contents of Alberta Butter.” Journal of Dairy Science, 53(2) 150–154.
Berardi, et al, "Macronutrient 2: Fat." The Essentials of Sport and Exercise Nutrition, 152 - 158.