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Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.
Foods like walnuts, eggs, steak, and vegetable oil look very different, but they have something in common, and that is they all contain fats, or lipids, which is another name for fats. Different lipids have different chemical makeups, and these variations allow us to classify lipids into different groups. In this lesson, we will look at the major classifications of lipids and the role each one plays in our nutritional health.
As we mentioned, different lipids have different chemical structures, but one thing lipids have in common is that they don't really like water. If you ever tried to stir oil, which is a type of fat, into water, you noticed that oil and water don't mix.
In our weight-conscious world, we tend to throw around the term fat fairly commonly, but when people talk about fat in their diet, they are usually referring to one of the major classifications of lipids, known as triglycerides. Triglycerides are the most common type of lipid present in our foods and in our bodies.
The name 'triglycerides' gives away its chemical makeup because it has 'tri-,' or three, fatty acids attached to one 'glyceride,' or glycerol molecule.
Fatty acids are long chains of carbon atoms with attached hydrogen atoms and a carboxyl group on one end. It's the fatty acids that we really refer to when we say foods contain saturated fats or unsaturated fats. In fact, you could use the terms saturated fatty acids and unsaturated fatty acids to mean the same thing. The level of saturation refers to how many hydrogen atoms surround each carbon atom. So, saturated fatty acids are saturated with hydrogen, meaning they have hydrogen atoms on each carbon in the chain and no double bonds.
Through their metabolism, animals tend to produce triglycerides with saturated fatty acids, so foods from animals, like beef and dairy products contain saturated fats. Saturated fats have been linked to an increased risk of heart disease. You can recall this fact by thinking of your arteries being saturated or coated with fat.
Unsaturated fatty acids are not saturated with hydrogen, and we see varying numbers of double bonds in the different unsaturated fats. Plants tend to produce triglycerides with unsaturated fatty acids, so we see these fats in vegetable oils and nuts. We typically think of plant foods as being healthy, so you can use this to remember that unsaturated fats play a role in lowering the risk of heart disease.
Lipids can also be classified as phospholipids, which can be described as a major classification of lipids that contains a water-loving phosphate group. Phospholipids have a glycerol molecule, like triglycerides, but they only have two fatty acids, as opposed to three. Phospholipids also contain a phosphate group and a polar group. This makes phospholipids unique, as far as lipids are concerned, because both the phosphate group and the polar group like water.
The rest of the molecule still hates water, but this quality makes phospholipids important components in cell membranes because they like to line up in parallel layers and form a barrier between watery environments, like those that exist around your cells.
Your body can make phospholipids, but you can also get them through your diet. When eaten, phospholipids will actually allow fat and water to mix. For example, the phospholipid 'lecithin' is found in foods like egg yolks, and it's what allows the oil and water that you add to a cake mix to blend together.
Steroids are another class of lipids. They are structurally very different than the other two classes because they contain four rings of carbon atoms and no fatty acids.
Cholesterol is the most common steroid. Cholesterol has a bad reputation because when we overeat foods that contain cholesterol, such as meat, eggs and cheese, we can increase the risk of heart disease. However, you could not survive without some cholesterol in your body. It's a component of your cell membranes and used as a raw material to help make vitamin D, bile salts and the hormones testosterone and estrogen.
Lipids can be classified based on their chemical structure. Triglycerides are the most common type of lipid present in our foods and in our bodies. Triglycerides have three fatty acids attached to one glycerol molecule.
Fatty acids are long chains of carbon atoms with attached hydrogen atoms and a carboxyl group on one end. Saturated fatty acids are saturated with hydrogen and found in foods from animals, like beef and dairy products. Saturated fats have been linked to an increased risk of heart disease. Unsaturated fatty acids are not saturated with hydrogen and found in foods from plants, like vegetable oils and nuts. Unsaturated fats play a role in lowering the risk of heart disease.
Phospholipids are a major classification of lipids that contains a water-loving phosphate group. Phospholipids have a glycerol molecule, two fatty acids and a phosphate group. Phospholipids are important components in cell membranes. One example of a phospholipid is lecithin, which is found in foods like egg yolks.
Steroids are another class of lipids. They contain four rings of carbon atoms and no fatty acids. Cholesterol is the most common steroid. Overconsumption can increase the risk of heart disease, but cholesterol is also a component of your cell membranes and used as a raw material to help make vitamin D, bile salts and the hormones testosterone and estrogen.
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Back To CourseHealth and Wellness
11 chapters | 103 lessons