 Hello and welcome to CNM's Naturopathic Nutrition Year 1. I'm Dee Clough, I'm a nutritionist, naturopath and herbalist and today I'll be talking to you about lipids. So let's take a look at our learning outcomes. So today what we're looking at is the structural characteristics of lipids and that's important because the different chemical structures alter the way that the lipids behave in the human body. We'll also look at dietary sources, functions, bioavailability and the metabolism of lipids and this will include quite an extensive discussion on the essential fatty acids. We'll also consider deficiency states and the therapeutic uses that apply to the essential fatty acids. Now here's an interesting consideration for you. The body of a lean, healthy man is composed of roughly 16% fat. While in a male with severe obesity, the fat content could account for up to 70% of body composition or 57 kilograms. And I guess the reason really to highlight that is to highlight that it's one of the reasons that dietary fat has become such a hotly debated issue because what is now being debated is that with this big increase in obesity does it actually relate predominantly to fat intake or does it relate to intake of another macronutrient? And these are some of the things that we'll look at today but realistically to have a body composition of 70% fat is hugely obese and in fact in a male anything over 25% body fat is considered too much. Women have a bit more flexibility, women naturally carry more body fat and anything over about 33% is considered a significant indicator of obesity. So what's the true player in this increase in obesity? Well when we start to consider it, it's one of the reasons that fat gets this really bad rap and people tend to forget that fat has and lipids generally have really important roles in the human body. So yes, they're a source of energy and obviously if we take in too much energy and calories it converts to stored fat but they also form part of every cell so they're vital for physiological and biological processes so things like hormone production. So these are really important considerations and what we're going to be progressively looking at is the types and amounts of fat that are ideal. The other thing that we need to consider in relation to lipids and fats is how farming and food processing have increased or altered the amounts and types of fats in the human diet and most notable is the intake we now have of trans fats and also the way that vegetable oils have been adulterated. So let's start taking a closer look. Let's take a little bit of a look at the great fat debate because fat intake has changed in recent times and most notably since fats were credited with causing heart disease which has become a really controversial issue and I think a lot of this stems from some of the research by Ancel Keys so Ancel Keys was an American physiologist and his focus was studying the impact of food or nutrition on health and he conducted a sort of very well known study the Seven Countries study which determined his research determined that high saturated fat intake would increase serum cholesterol and consequently increase risk of heart disease and so his research I guess was instrumental in changing society's perception of fats it is possible that Ancel Keys gets held a whole lot more responsible for the way the industry food industry and government bodies have gone regards fat intake recommendations but regardless his research was that starting point. Interestingly if you look into the work that Ancel Keys did he was an advocate of what we would now refer to as the Mediterranean diet and I guess the interesting point is that he didn't actually advocate a low fat diet he advocated moderating saturated fats increasing unsaturated fats and having a lot more fresh fruits and vegetables and also a healthy lifestyle with exercise. However progressively what happened is that his research and other research kind of was grabbed hold of and we started to see recommendations like the recommendations of the American Heart Association which then started pushing for a low fat diet so especially saturated fats but low fat generally and of course this is when we started to see products coming out like low fat milk and low fat yogurt etc etc and the unfortunate thing is that what was done to replace the fat that was removed was the addition of carbohydrates in the form of refined carbohydrates and sugars and I don't know that we can necessarily attribute that to Ancel Keys however it is the way that the food industry went along with that I guess once there was this linking of cholesterol and heart disease was this sort of great body of research looking into medications to reduce cholesterol and indeed that led to the production of statins now bear in mind that Ancel Keys research was published in 1978 again in the mid 60s the first commercially available statins were not available until 1987 so again I don't know that we can hold Ancel Keys responsible for the production of statins and this is some of the debate that you'll see is Ancel Keys who's no longer alive and can't defend himself being held responsible for the fact that statins are now one of the biggest selling classes of drugs worldwide regardless we've had this real push of low fat products of people getting put on statins the minute their cholesterol gets a little bit high and the interesting thing is that it doesn't actually align with decreased risk of coronary heart disease so we'll look at that a little bit more as we work our way through the lecture