To begin all fat sources contain a mixture of:
o Saturated
o Unsaturated
o Monounsaturated
o Polyunsaturated fatty acids, although proportions vary depending on the source.
For many years nutritionists have spoke about saturated fat, unsaturated fat and polyunsaturated fat, but these three categories are just a small part of the overall picture when it comes to fat quality. To understand fat quality we need to look at certain fat components called fatty acids.
In terms of chemistry fatty acids are like chains consisting of links, they can be short, medium and long, depending on the number of links they contain. Our bodies need all three kinds of fatty acids to remain healthy, as well as both saturated and unsaturated fats.
Saturated fatty acids – these are helpful structurally because they help stabilize cell membranes, and they are not susceptible to damage, as they are non interactive.
o Saturated fats are usually hard at room temperature e.g. butter and lard.
Unsaturated fatty acids – These are much more interactive and susceptible to damage, but they are critical in the body, as they provide flexibility to cell membranes, and allow the cells to communicate with each other.
o Unsaturated vegetable oils include sunflower, safflower, and canola are liquid at room temperature and recognizable as liquids.
Essential Fatty acids – we must consume these from the diet!
Omega-3 and Omega-6 fatty acids have been the subject of intense research since the mid 1990’s, and it is now clear that our balance of omega-6 to omega-3 affects our health as much as any other aspect of dietary fat.
There are two essential fatty acids (EFAs) that we must consume in food:
o Linoleic acid (LA), an omega 6 fatty acid.
o Alpha-linoleic acid (ALA) and omega 3 fatty acid.
The ratio between omega 3 and omega 6
Western diets are deficient in omega-3, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved, and their genetic patterns were established. High amounts of omega-6 polyunsaturated fatty acids and a very high omega-6/omega-3 ratio, as is found in today’s western diets promotes many diseases including cardiovascular disease, cancer and autoimmune diseases. Whereas increased levels of omega-3 (PUFA) exert suppressive effects.
Consuming more omega-3 fatty acids and less omega-6 fatty acids
The first step toward achieving an optimum fatty acid ratio is to consume more whole foods that are rich in beneficial omega-3 fatty acids, in which most of us are deficient. Animal products are the best sources of omega-3 fatty acids, this is especially true of oily fish such as mackerel, salmon and sardines, and grass fed animals. The best plant-based source of omega-3 fatty acids is most likely flaxseed, however most other seeds and their oils such as peanuts and sesame seeds provide more omega-6 than omega-3, making them unsuitable for correcting an imbalance.
The easiest way to reduce our intake of omega-6 fatty acids is to avoid consuming the processed vegetable and seed oils that are rich in it. These include canola oil, sunflower oil, safflower oil and corn oil. Most of them are made from crops that are usually genetically modified and/or heavily sprayed, making them even unhealthier. Coconut oil and olive oil are relatively low in omega-6 acids.
Unsaturated fatty acids
Type of unsaturated fatty acid Key unsaturated fatty acids Best sources
Monounsaturated Oleic acid Olive oil, canola oil
Polyunsaturated (omega-6s) Linoleic acid Safflower oil, sunflower oil, sesame oil
Gamma-linolenic acid Borage oil, evening primrose oil, human milk
Arachidonic acid Beef fat, egg yolk
Polyunsaturated (omega-3s) Alpha-linolenic acid Flaxseed, pumpkin seed, hemp seed, walnut
Eicosapentaenoic acid (EPA) Fish oil
Docosahexaenoic acid (DHA) Fish oil
Food classified by Types of Fats
Saturated fats Monounsaturated fats Polyunsaturated fats Omega 6/omega 3 percentage of total fat
Beef Olive oil Soybean oil 51.00% 7.00%
Pork Canola oil Safflower oil 74.00% trace
Lamb Almond oil Sunflower oil 69.00% trace
Poultry Avocado Corn oil 61.00% 1.00%
Coconut oil Macadamia nut Sesame oil 42.00% trace
Milk Cashew nut Peanut oil 34.00% trace
Butter Rice bran oil 38.00% 2.00%
Cheese Wheat germ oil 55.00% 7.00%
Grapeseed oil 70.00% trace
Flaxseed oil 13.00% 54.00%
Pumpkin seed oil 43.00% 5-15%
Walnut oil 53.00% 3-5%
Chia seed oil 19.00% 57.00%
Poppyseed oil 62-68%v tracec
Cholesterol
Manufactured in the body primarily the liver, although all tissues of the body expect the brain can make it, cholesterol is present in almost all cells and is high in the liver, brain and nervous tissue and the blood.
Foods containing cholesterol:
o egg yolk
o meats
o animal fats including milk products
It is not present in plant foods and cannot be produced by any plants, although it is found in the membrane of some bacteria.
o LDL cholesterol (“the bad guy”) – carrying cholesterol out from the liver to the rest of the body.
o HDL (“the good guy”) – Works in the opposite direction, bringing cholesterol back to the liver from other tissues and organs.
A key point is the continuing need for us to increase our HDL levels and maintain or lower our total cholesterol. Cutting down on our total cholesterol intake cannot help us increase our HDL levels. Getting MORE EXCERCISE can do that, also along with increasing our dietary fibre intake and our intake of plant foods.
MAIN ROLES OF FATS
o Fat plays a diverse role in human nutrition, as they are important source of energy, both for immediate use by the body and creating a storage depot for later utilisation when food intake is reduced.
o Dietary fat helps towards to absorption of fat soluble vitamins including Vitamin A, D, E and K.
o Fats are important to our nervous system as well as in the production of sex hormones and the important hormones like prostaglandins.
o Fat below the skin helps prevent heat loss, and protects against external temperature changes.
o Every body cell and every tissue and organ is dependent on fats in the body for its health. Fats are required for cell to cell communication.
o Essential to keep our skin healthy!
References:
o TSimopoulos (2002), The importance of the ratio of omega-6/omega-3 essential fatty acids.
o http://science.naturalnews.com/Omega_3_fatty_acid.html
o Human Nutrition (2011) Catherine Geissler and Hiliary Powers
o https://www.cholesterolmatters.co.uk/public/cholesterol/understanding-cholesterol-levels
o Staying Healthy with Nutrition (2006). Elson M. Haas, MD.