all right welcome to 1023 unit 3 this is going to focus on chapter 6 and lipids okay let's start out talking about lipids lipids are commonly known as fats and of course fat is going to be crucial for many of our bodily functions but lipids are insoluble in water which is going to affect how they are transported and stored in the body there are three major lipid groups that we're going to talk about triglycerides phospholipids and steriles so let's explore each of these in detail triglycerides are your most common type of lipid when we're talking about lipids these are going to make up about 95% of the fats that we consume they are composed of one glycerol molecule and Three fatty acids triglycerides are the primary form of fat storage in our bodies and that of course is stored in adapost tissue and it serves as the primary energy source triglyceride food sources might uh in Encompass animal fats vegetable oils but Bakery items and dairy products also have a significant source of fat now in addition to being our body's main storage form of energy it also is going to help us insulate our bodies protect our bodies and also Aid in the storage of fat soluble vitamin absorption okay let's talk about those fatty acids fatty acids are going to vary in how long their carbon chain lengths are the shorter the chain the quicker it is digested and when we look at the chain lengths you can characterize them as short medium or long and within that you can look at how the carbons are bonded if they are bonded to the maximum number of hydrogen atoms we can call them saturated but if they do not have the maximum number of hydrogens we call them unsaturated and that'll change their shape so if you look at this the screen here you can see that um saturated fatty acids at the top are saturated with hydrogen atoms they have no double bonds to any of the carbon molecules and they're typically solid at room temperature because of that because those those fatty acid Tails can sit nicely on top top of one another whereas the monounsaturated or polyunsaturated fatty acids have lost a hydrogen atom and those carbon atoms like to make four bonds and so the carbon atoms double bond to each other but those double bonds make the tail have a little kink in it and that allow doesn't allow them to sit nicely on top of one another so they are liquid at room temperature now just some examples of some saturated fatty acids we'll think things that are fats that are solid room temperature so coconut oil butter cheese um cream lard beef fat and also um olive oil and canola oil and peanut oil those are unsaturated fatty acids or soy canola corn and safflower oils those are polyunsaturated fatty acids so again where do we want to be careful with ingesting these well you particularly want to be careful with the saturated fats because as they can uh solidify they also will do that in your body and they can increase the risk of cardiovascular disease because of it they might increase your blood cholesterol levels as well and so if you take it the look at some examples of foods that are higher in saturated fats you you're talking your butter your cheese and your red meat and of course you just want to be mindful of your intake of those again with you with the idea of the shape here it's really the shape that's going to determine the the physical state of those fatty acids as well so when you have the trans and saturated fatty acids those have straight carbon chains and because of their straight structure they can pack the more tightly together and of course like I said that packing results in fats that are solid room temperature like butter or lard unless you heat them and on the other hand the unsaturated fats have one or more double bonds and that creates a kink or bends the chain and it prevents those molecules from packing so closely together and they're typically liquid at room temperature like olive oil or canola oil which are good examples okay moving on phospholipids phospholipids are another type of fat and phospholipids are super important because they uh make up the main structure of of your cell membranes you can also find them in foods like egg yolks and soybeans but the really important part for your body is they're critical for the cell membrane structure and they function also as emulsifiers that'll help you transport lipids through your bloodstream now the reason for that is they are amphipathic meaning they have two parts to their structure one of them being hydrophilic and one of them being hydrophobic filic and phobic Hydro water lover for hydrophilic and water scale or water afraid for hydrophobic so we'll come back to these in a little bit when we talk about how you move lipids through the body and then the last one we want to talk about are sterols sterols are steroids um an important one that we want to talk about here is cholesterol now remember cholesterol is produced by our own bodies but you also find it in the foods that are animal-based and cholesterol might have a sort of scary like meaning to you but it it doesn't mean that you can't have any of it uh they are critical cholesterol is critical and it's essential for cell membrane structure hormone production synthesis of vitamin D hormones um but and biosynthesis but you really do want to be careful because too much cholesterol is super problematic for your health and we'll get into that in a little bit okay now let's get back to the fatty acid talk again I want to discuss essential fatty acids now why are they essential well essential fatty acids are for example like linolic acid which is an omega-6 fatty acid and um we've got omega3 which is alpha linolic acid um or sorry yeah I had that right those H those are essential because you got you have got to get them through your diet uh you can get Omega 6 in vegetable oils and nuts and omega3 is in fish and flax and walnuts and they're really important because they play a massive role in reducing inflammation in the body which will also help you prevent heart disease risk now another example of why these uh essential fatty acids are so important are these uh molecules called eosino they're kind of like steroids but they're they're hormonik compounds they're produced by essential fatty acids and they help regulate a whole number of things like your gastrointestinal tract and secretory activity of your cells and blood clotting Vaso dilation and Vaso constriction so essential fatty acids super important to get in your diet let's talk about hydrogenation what is it why do we do it well hydrogenation is simply taking uh hydrogen atoms and adding them to unsaturated fatty acid and so that'll make them more saturated and more solid as a byproduct of that now problem is that that creates trans fat trans fatty acids and lots of Studies have shown that increased trans fat in the diet results in increased blood cholesterol and increased risk of cardiovascular disease so then why do they do it well of course it comes back to the almighty dollar uh hydrogenation is used in commercial food processing and it helps to improve food shelf life and it resists rans idity it's you know why you can have a Twinkie sit on the counter for 20 years and probably still eat it um you know it probably tastes really good and it doesn't mean that you can't have it but you really want to limit trans fats and saturated fats all right so why do we use lipids of the body well aside from they provide lots of energy nine kilo calories per gram but they also are our major fuel at rest and during endurance exercise they also Pro are how we store energy for later use and they help you with your um hormone production and absorbing those fat soluble vitamins um and they also are found in your cell membranes and they produce steroid-based hormones they protect your body uh with your adapost tissue and it also just they just taste really good and they help you feel Fuller longer uh but the downside of that is they're also very very caloric so maybe we should take a look at the guidelines for fat intake and uh how we might find foods that might have hidden fat meaning you don't think that it would because it doesn't look like an animal fat but it's got a ton of it so um first of all the amdr for fat intake is 20 to 35% of your total daily energy intake but of that saturated fats the ones we talked about before should really only be like 7 to 10% the reason for that is we really want to avoid those because of how they affect our cholesterol and might point to uh potential cardiovascular system problems so what do we mean by hidden or invisible fats so lots of foods contain hidden fats like baked goods for example usually they are made using full fat Dairy products um fast food is going to have a lot of these hidden uh fats and so it's really essential if you can to read your labels correctly and understand that just because something might say fat free or lowfat doesn't mean that it's calorie free remember there are other ways to get calories in Foods now I just want to end this by saying that baked goods are not quote bad fat foods don't have a moral value healthy dietary patterns are all about balance and moderation variety and adequacy so you can have that piece of cake just don't have the whole cake now one thing that we came up with scientists came up with in like the 80s was um that fat was making people fat and so they came up with these molecules that were fat replacers to lower the fat content of foods uh this did not work because of course fat is not the only thing that causes people to get fat um but we put them in chips and cakes and cookies and people just thought you could eat all this CU it was free fat fat free but it's doesn't work that way there's still calories and things and the other downside of them is they might cause lots of stomach issues in when people eat large amounts of them um and so you just want to be sure that uh you know understand that fat is not bad you can have fat but uh make sure you're just not you're not eating too much and um these other fat replacers might not be uh might not be a better substitute even though they aren't providing lots of calories okay so maybe we should talk about how we look at a food uh food product nutrition fact label and determine how much of the calories in a serving is coming from fat so in this uh wy's weeners the pork sausage here has per one sausage 140 calories but in that um of that 140 calories there's 13 G of fat so if I want to calculate the percentage of calories from fat in that food product I need to know how many grams of fat I KN I do know that and then I need to multiply that number by nine kilo calories per gram so in this case we can see 13 * 9 would be 117 kilo calories from fat now we just want to find out what percentage of that total 140 is 117 so you take 117 divided by the total 140 and then multiply by 100 so 117 / 140 = 835 7 multiplied by 100 gives us 83.5 s calories derived from fat so this thing is basically all fat um but I bet it tastes good and again you can have it it's fine just make sure that you're taking control of your diet now let's talk about how we actually digest lipids and where we we do that remember that lipids are not water soluble they cannot get into the bloodstream uh and so they're going to need bile and and digestive enzymes from the pancreas in order to be digested and then we're going to absorb them with the help of our my cells which is a spherical compound made up of that bile salt and phospholipids that can help capture lipid digested particles and transport them into the interos sites for absorption let's talk about uh ocytes uh where are they they're in the small intestine that's where all of the fat is digested once it gets to the large intes only less than 5% of the fat that is in there is going to get in there and then it will get excreted it will no longer be absorbed in the body but remember the digestion story starts at the mouth uh lingual lipase is secreted and but little or no fat is digested once you get to the stomach gastric lipase is secreted and a little bit of fat is digested then the liver is going to come in and produce bile stored in the gallbladder and then the gallbladder releases it into the bile duct along with enzymes from the pancreas and all of that is going to go and meet in the small intestine to digest and absorb the particles into dadum in the Jenum bile then gets resorbed in the ilium and goes back to your gallbladder okay now let's talk about the actual absorption of this lipid product into the bloodstream we are now in the ocytes which are the cells of the intestinal lining and those components that we just digested are actually going to be formed right back into triglycerides but they are still not able to get into the blood treatment so we have to package them into what are called lipoproteins and release them then into the bloodstream now A lipoprotein all it is is a spherical compound with triglycerides in the middle and phospholipids making up the outside a kyom micron is a specific lipoprotein that's produced that when we transport lipids from a meal product so this is the overall View you can pause here and make sure that this makes sense and that you know all the players here let's uh next explore the different types of lipoproteins and their roles in the body remember that they are essential for transporting lipids through the bloodstream because again I've said it a couple times now lipids are not water soluble if you think about pouring some olive oil into water you can see that that olive oil is going to bead up on the surface creating two separate layers because water is water and fat or is hydrophobic so first let's talk about the vldls the very low density lipoproteins they are primarily produced by the liver and are rich in triglycerides make up about makes up about half of their content and so their main function is to transport triglycerides to cells and add aose tissue for storage however if you have a diet that's super high in fat simple sugars and excess calories that's going to increase your vldl levels and that's not ideal on the bright side though if you have regular exercise you can reduce V LDL levels and promote better heart health now ldls are going to result when those vldls release their triglycerides um and so as a result the ldls have a higher concentration of the cholesterol phospholipids and proteins and that makes them even more dense now ldls are supposed to deliver cholesterol to cells that have LDL receptors but if our diet is high in those saturated trans fats those receptors are going to get blocked causing cholesterol to be released right into the bloodstream and so if you take a look at your blood test and your doctor says that there are elevated LDL levels that's associated with the risk of arteriosclerosis and cardiovascular disease and so this is what the doctor might call like bad cholesterol so you want to keep those ldls low on the other hand though you want hdls hdls are highdensity lipoproteins they are small dense hpo proteins with very little cholesterol content and they are often referred to as good cholesterol because what they do is they circulate through the blood and pick up that excess cholesterol from tissues and lipoproteins and return it to the liver for excretion and so if you look at your blood test and you have high HDL levels then that's really beneficial and it'll help you reduce the risk of cardiovascular disease so in summary vldls and lals they can contribute to cardiovascular problems if they're not managed properly h hdl's will also play a protective role in maintaining your heart health so it's important to balance not only your diet but also your lifestyle to keep your lipoproteins at healthy levels here's just a picture of the lipoprotein structure you can see those hydrophilic heads in the pink on the outside surrounding the light the lipids that would not otherwise like to be in a bloodstream here's that entire process that we've talked about you can stop here and make sure that you understand where we are okay finally let's talk about some health concerns so dietary fat is essential for health that's the first thing I want to talk about you cannot have no fat that just that will not work for the body the problem is that we live in a society where you can get lots of fatty foods very easily and those uh cause high intakes of fat and that might increase it does certainly increase your risk of cardiovascular disease it also increases your risk of obesity and even certain Cancers and so it's just really important that we balance our healthier diet with a healthier lifestyle and also if we can choose to eat healthier fats that's a great idea avoid those trans fats and you should be fine okay what is cardiovascular disease just in case you're wondering well it's a general term for any abnormal condition involving dysfunction of the heart or blood vessels and unfortunately it's the leading cause of death in the United States um some of these are hypertension arteriosclerosis coronary artery disease Strokes um you can see progression of arteriosclerosis here where an artery has been blocked fully by a blood clot that is formed that can cause a stroke or a heart attack and so this is no good now there are risk factors of cardiovascular disease like we've talked about like eating too much fat um and trans fat at that but there are also some other risk factors that you cannot control for example your age and your genetics that's out of your control obesity there are even some studies now that say that there really isn't as much control in obesity as we previously thought um and there are some medications coming out uh that we you know OIC for example is working with the brain gut the gut brain hormone system uh to help people who are really struggling with that uh they are not eating just because they want to eat they're eating because their brain is telling them they need to eat um but that coupled with a lack of physical activity and smoking those are things that you can control type 2 diabetes however you cannot if you are a person who's prone to inflammation um if you have an abnormal blood lipid level and if you're eating a high-fat diet these are all risk factors for cardiovascular disease so how do we prevent them well of course like we said decrease your saturated fat intake and your trans fat intake and get off the couch every once in a while and also increasing fiber has been shown to be great for your health now this is the end of this video let learning objective 13 is actually covered in an activity in unit 3 for this class thanks for watching and let me know if you have any questions