Lipids - 3/4

>> Everything in the lipid family is all about triglycerides and fatty acids. Remember, we have phospholipids. A phospholipid is mostly lipid. It has glycerol. It has a fatty acid and a second fatty acid. But on the third spot, it has a phosphate group. And then at the end of it, it has choline. So here we have something that, the fatty acids don't like water, but the phosphate and the choline do. So you have something that can be used in manufacturing. Like egg has lecithin. Lecithin is phospholipid. And so you use eggs when you make chocolate chip cookies so that you can spread the fat around. It makes for when you bite into that cookie, it's delicious. It's creamy, it tastes great. Well, it's the egg with its lecithin that has moved the fat around in the body. We use phospholipids to form the membrane of cells, and we use two layers so that the round, which we call the head of a phospholipid, is looking at water, but the tails, which are the fatty acids, are not looking at water and they're trying to get away from water. So phospholipids are used in every cell of the body. What else you will find in every cell of the body is cholesterol. And cholesterol doesn't look like a triglyceride or a phospholipid. It is made up of four fused rings. At each point in that ring there's carbon and hydrogen. So some people say it looks like chicken wire. Vitamin D3 is a sterile along with bile, and they serve the purpose. Bile emulsifies fats as you know from the digestion chapter, and cholesterol is part of cell membranes. We eat our lipid, and it has to be digested. Nothing really happens to it in the mouth and the stomach, other than our body heat will melt it and make it a little bit less difficult to digest. But once it hits the duodenum, we will have the bile coming from the gallbladder that will emulsify the fat and then allow the pancreatic lipase to be able to hydrolasize the triglycerides into smaller parts. If we have any soluble fiber in this meal that we have had, then the soluble fiber will have cholesterol sticking to it. And it's a fiber, so it's going to exit in the feces. Now we have a problem. We have a material that after digestion, has to be transported from the small intestine to all parts of the body. And remember, we have a material that doesn't like water. And most of our body is water. So what we have to do is provide carriers. And so those carriers, after we have digested our meal, and there's probably some fat in that meal, we have to supply it with a carrier. The first carrier will be a kilomicron. A kilomicron will be inside the villus in the lacteal, and it will take a big load of freshly digested and absorbed triglycerides in the lymph system, which will go to the heart. From the heart it will go into the general circulation. Sooner or later, it will get to the liver. And what the liver will do is it will take the kilomicron and break it down, get the triglycerides out, use what it needs for its own energy, because triglycerides are made of fatty acids. Fatty acids have potential energy, 9 calories per gram. So we take what we need, but we'll have stuff left over. We ought to share. So what the liver will do is make a lipoprotein. In this case it's a VLDL, which is a very low density lipoprotein. Then that VLDL has -- pretty much half of it is triglycerides. And it will go out and bump along and spill, and it also picks up cholesterol. And it becomes a low density lipoprotein, an LDL, which is probably -- many times people call that the bad cholesterol. But it's really a bad carrier of cholesterol. The liver also makes a very small lipoprotein called HDL. And the HDL will leave the liver somewhat empty, and it's programmed to pick up cholesterol and bring it back to the liver. It carries mostly protein. So we have kilomicrons, VLDLs, LDLs, and HDLs. It's not important to know the percentage of what it contains, but kilomicrons carry mostly triglycerides. VLDLs carry mostly triglycerides. LDLs carry mostly cholesterol. And HDLs carry mostly protein. We don't eat kilomicrons, VLDLs, LDLs, HDls, we make it. Some people are genetically endowed to make a lot of LDLs, which is not a good thing, because LDL is an indicator of risk for heart disease. Some people make a lot of HDLs, and that is a good thing, because it's protective. So saturated fat and trans fats impacts LDLs. So you want to not only look to how much saturated fat but how much cholesterol you have in your diet. Fiber from the last chapter is only found in plant. For this chapter, cholesterol is only found in animal. So a shrimp, an egg looks like it stands out as far as a high amount of cholesterol. There's a little bit in butter, there's a little bit in milk and yogurt. But they're animal products so you'd expect to find it there. If you want to really increase your cholesterol, you would be eating organs, like the intestines, which would be tripe, maybe eat liver, maybe eat brain. That's very high in cholesterol. So animal is always going to give you cholesterol. So what should you do about your choices to be healthy for the lipid.