Fats: the good, the bad and the ugly! pt 1

There are all kinds of fats. Good, bad and ugly ones. We are going to look at them over the next few posts. Let's start by taking a look at the different types:

The bad fats

Saturated fat

Saturated fat is fat that consists of triglycerides containing only saturated fatty acids. Saturated fatty acids have no double bonds between the individual carbon atoms of the fatty acid chain. That is, the chain of carbon atoms is fully "saturated" with hydrogen atoms. There are many kinds of naturally occurring saturated fatty acids, which mainly differ in number of carbon atoms, from 3 carbons (propionic acid) to 36 (hexatriacontanoic acid).

They raise LDL cholesterol as well as the total blood cholesterol. Examples of foods containing a high proportion of saturated fat include animal fats such as cream, cheese, butter and ghee; suet, tallow, lard and fatty meats; as well as certain vegetable products such as coconut oil, cottonseed oil, palm kernel oil, chocolate, and many prepared foods.


Trans fats

Trans fat is the common name for unsaturated fat with trans-isomer (E-isomer) fatty acid(s). Because the term refers to the configuration of a double carbon-carbon bond, trans fats may be monounsaturated or polyunsaturated but never saturated.

Unsaturated fat is a fat molecule containing one or more double bonds between the carbon atoms. Since the carbons are double-bonded to each other, there are fewer bonds connected to hydrogen, so there are fewer hydrogen atoms, hence "unsaturated".

The process of hydrogenation adds hydrogen atoms to cis-unsaturated fats, eliminating double bonds and making them into partially or completely saturated fats. However, partial hydrogenation, if it is chemical rather than enzymatic, converts a part of cis-isomers into trans-unsaturated fats instead of hydrogenating them completely. Some occur naturally in trace amounts in meat and dairy products derived from ruminants.

No trans fats are essential fatty acids; indeed, the consumption of trans fats increases the risk of coronary heart disease by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol. Health authorities worldwide recommend that consumption of trans fat be reduced to trace amounts. Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.

Trans fats raise LDL cholesterol (the bad cholesterol) and lower HDL cholesterol (the good cholesterol).

Examples are doughnuts and pastry, deep fried foods such as fried chicken fish and french fried potatoes, and imitation cheese. Snack chips, cookies, and crackers often contains high amounts of trans fat as well. Trans fat can also be found in some natural sources including milk, sheep, goats, deer, buffalo, and marsupials. These sources have been found to have significantly lower levels of trans fatty acids than those which are a result of manual hydrogenation. For a more detailed look at this, follow this link: (The Phantom fat)


Good Fats

Monounsaturated fats

In biochemistry and nutrition, monounsaturated fats or MUFA (MonoUnsaturated Fatty Acid) are fatty acids that have a single double bond in the fatty acid chain and all of the remainder of the carbon atoms in the chain are single-bonded. By contrast, polyunsaturated fatty acids have more than one double bond.

Fatty acid viscosity (thickness) and melting temperature increases with decreasing number of double bonds. Therefore, monounsaturated fatty acids have a higher melting point than polyunsaturated fatty acids (more double bonds) and a lower melting point than saturated fatty acids (no double bonds). Monounsaturated fatty acids are liquids at room temperature and semisolid or solid when refrigerated.

Although polyunsaturated fats protect against cardiovascular disease by providing more membrane fluidity than monounsaturated fats, they are more vulnerable to lipid peroxidation (rancidity). On the other hand, some monounsaturated fatty acids (in the same way as saturated fats) promote insulin resistance, whereas polyunsaturated fatty acids are protective against insulin resistance. See here: Role of Fatty Acid Composition in the Development of Metabolic Disorders in Sucrose-Induced Obese Rats and The influence of dietary fat on insulin resistance

Monounsaturated fats lower total cholesterol and LDL cholesterol (the bad cholesterol) and increase the HDL cholesterol (the good cholesterol).

Monounsaturated fats are found along with saturated fat in natural foods such as red meat, whole milk products, nuts and high fat fruits such as olives and avocados. Olive oil is about 75% monounsaturated fat while tea seed oil is commonly over 80% monounsaturated fat and Canola oil is about 58% monounsaturated fat. Tallow (beef fat) is about 50% monounsaturated fat and lard is about 40% monounsaturated fat. Other sources include macadamia nut oil, grapeseed oil, groundnut oil (peanut oil), sesame oil, corn oil, popcorn, whole grain wheat, cereal, oatmeal, safflower oil, sunflower oil, tea-oil Camellia, and avocado oil.


Polyunsaturated fats

In nutrition, polyunsaturated fat, or polyunsaturated fatty acid, are fatty acids in which more than one double bond exists within the representative molecule. That is, the molecule has two or more points on its structure capable of supporting hydrogen atoms not currently part of the structure. Polyunsaturated fatty acids can assume a cis or trans conformation depending on the geometry of the double bond.

The lack of the extra hydrogen atoms on the molecule's surface typically reduces the strength of the compound's intermolecular forces, thus causing the melting point of the compound to be significantly lower. This property can be observed by comparing predominately unsaturated vegetable oils, which remain liquid even at relatively low temperatures, to much more saturated fats such as butter or lard[clarification needed] which are mainly solid at room temperature. Trans fats are more similar to saturated fat than are cis fats in many respects, including the fact that they solidify at a higher temperature than cis fats.

Polyunsaturated fat can be found mostly in nuts, seeds, fish, algae, leafy greens, and krill. Whole food sources are always best, as processing and heating may damage polyunsaturated fats. Omega-3 fatty acids in fish oil, fish and seafood have been shown to lower the risk of heart attacks.(Omega-3 fatty acids, fish oil, alpha-linolenic acid) Omega-6 fatty acids in sunflower oil and safflower oil may also reduce the risk of cardiovascular disease.(The role of dietary n-6 fatty acids in the prevention of cardiovascular disease.)

Polyunsaturated fats also lower total cholesterol and LDL cholesterol.

I will stop here for now. We will look more at the types of cholesterol next time.