Types of Fats
Fatty acids, solid fats and trans fats
Oils and fats are made up of fatty acids, which can be saturated, monounsaturated or polyunsaturated.
Solid fats are fats that are solid at room temperature, mostly from animal products; meat, milk, butter, beef fat (tallow, suet), chicken fat, pork fat (lard), shortening. Solid fats are loaded with saturated fats. There are also a few plant oils, including coconut oil and palm kernel oil, which are high in saturated fats and for nutritional purposes should be considered to be solid fats. Solid fats like stick margarine can be made from vegetable oils through adding hydrogen to increase the shelf life and flavor stability of foods containing these fats – a process called hydrogenation.
Hydrogenation produces trans fats, which can be found in vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with, or fried in, partially hydrogenated oils. A small amount of trans fat is found naturally, primarily in dairy products, some meat, and other animal-based foods. Solid fats are loaded with saturated fats, which like trans fats in the diet, and dietary cholesterol, raises the LDL cholesterol levels in the system.
Fatty acids are molecules that contain carbon atoms bonded to other carbon atoms, and if all of these carbon – carbon bonds in the fatty acid are single bonds then the carbons atoms are said to be saturated and the fatty acid termed a saturated fatty acid.
Saturated fat is harmful – it is a major risk factor for heart attacks and strokes. The body can synthesize its own saturated fatty acids for particular purposes – adipose tissue, the layer of fat under the skin, is almost entirely composed of saturated fatty acids. So we don’t actually need to include ANY saturated fat in our diet.
Diets high in saturated fat (or high-glycemic index carbs) usually lead to an increased production of cholesterol, the main component of arterial plaque, which causes a narrowing of arteries (atherosclerosis) – although the exact mechanism creating arterial blockages is not clear, nor is it understood why some people can consume large amounts of saturated fats but have comparatively healthy arteries.
Unsaturated fatty acids are those whose carbon atoms have bonds other than single (double or triple).
If a molecule has one double or triple carbon bond it is a monounsaturated fatty acid – chief sources are olive oil, chicken and almonds, and also canola and peanut oils, and avocados.
If a molecule contains more than one double or triple carbon bond it is called a polyunsaturated fatty acid – major sources are fish and corn, soybean oil and safflower oil, also sesame and sunflower seeds, many nuts and seeds, and their oils.
Importance of unsaturated fats in the body
Structures in the body like the cells in wall membranes contain large quantities of polyunsaturated fatty acids. If the body lacks sufficient amounts of polyunsaturated fatty acids to use in cell formation, saturated fatty acids are used instead, especially if they’re high in the diet. The membrane that is formed will then have different properties from one made up of polyunsaturated fatty acids, leading in the long term to health or disease problems.
The lesson to be learned here is that a healthy diet should include foods containing polyunsaturated and monounsaturated fats, rather than those containing saturated fats.