The most comprehensive explanation of fats and oils, the good and bad oils, their role in regulating blood cholesterol, saturated, trans (and cis! who knew these terms came from chemistry) fats, why coconut oil is actually pretty bad for you, etc.
I just read this book about 17 different chemical compounds, including oils. Itâs very informative, especially in this area that there is so much talk about, but Iâve never been able to find a complete explanation of all these different properties of oils and fats, and what words like âsaturatedâ etc. really mean. Finally! This helped me a lot and I wanted to put it out there for anyone else curious.
This passage is from the book by Penny Le Couteur and Jay Burreson, âNapoleonsâ buttons: How 17 molecules changed historyâ, from the chapter on Oleic Acid, particularly pages 277-281:
âThe monounsaturated, eighteen-carbon oleic acid is the major fatty acid of acid of olive oil. Although oleic acid is found in other oils and also in many fats, oilve oil is the most important source of this fatty acid. Olive oil contains a larger proportion of monounsaturated fatty acids than any other oil. The percentage of oleic acid in olive oil varies from 55 to 85 percent, depending on the variety and the growing conditions, cooler areas producing a higher oleic acid content than warmer areas. There is now convincing evidence that a diet with a high proportion of saturated fat can contribute to the development of heart disease. The incidence of heart disease is lower in the Mediterranean region, where a lot of olive oil -- and oleic acid -- is consumed. Saturated* fats are known to increase serum cholesterol concentrations, whereas polyunsaturated fats and oils lower these levels. Monounsaturated fatty acids, like oleic acid, have a neutral effect on the serum cholesterol level (the level of cholesterol in the blood).
The relationship between heart disease and fatty acids also involves another factor: the ratio of high-density lipoprotein (known as HDL) to low-density lipoprotein (known as LDL). A lipoprotein is a water-insoluble accumulation of cholesterol, protein, and triglycerides. High-density lipoproteins -- often called the âgoodâ lipoproteins -- transport cholesterol from cells that have accumulated too much of this compound back to the liver for disposal. This prevents excess cholesterol from depositing on artery walls. The âbadâ lipoproteins, LDLs, transport cholesterol from the liver or small intestine to newly formed or growing cells. While this is a necessary function, too much cholesterol in the bloodstream ultimately ends up as deposits of plaque on the artery walls, leading to narrowing of the arteries. If the coronary arteries leading to the heart muscles become clogged, the resultant decreased blood flow can cause chest pain and heart attacks.
It is the ratio of HDL to LDL, as well as the total cholesterol level, that is important in determining the risk of heart disease. Although polyunsaturated triglycerides have the positive effect of reducing serum cholesterol levels, they also lower the HDl:LDL ratio, a negative effect. Monounsaturated triglycerides like olive oil, while not reducing serum cholesterol levels, increase the HDL:LDL ratio, that is, the proportion of good lipoprotein to bad lipoprotein. Among the saturated fatty acids, palmitic and lauric acids raise LDL levels appreciably. The so-called tropical oils -- coconut, palm, and palm kernel -- which have high proportions of these fatty acids, are particularly suspect in heart disease because they increase both serum cholesterol and LDL levels.
Today one method of improving the stability and increasing the shelf life of oils is the elimination of some of the double bonds by hydrogenation, a process of adding hydrogen atoms to the double bonds of unsaturated fatty acids. The result is also a more solid triglyceride; this is the method used to convert oils into butter substitutes like margarine. But the process of hydrogenation also changes the remaining double bonds from the cis configuration to the trans configuration, where the carbon atoms of the chain are on opposite sides of the double bonds.
Trans fatty acids are known to elevate LDL levels but not as much as saturated fatty acids.
*Saturated in this case means saturated with hydrogen; no more hydrogen can be added to the fatty-acid portion of the molecule, as there are no carbon-to-carbon double bonds that can be broken to allow the attachment of more hydrogen atoms. If such bonds are present in the fatty acid, it is termed unsaturated. Unsaturated fatty acids contain at least one carbon-to-carbon double bond. If there is only one of these double bonds, the acid is referred to as monounsaturated; with more than one double bond it is polyunsaturated.
Examples of saturated fatty acids: lauric acid, myrictic acid, palmitic acid (palm oil), stearic acid (beef tallow).
Monounsaturated: palmitoleic acid, oleic acid.
Polyunsaturated: linoleic acid, linolenic acid.â
