Olestra
Nat Cooper

Chemical Concepts
Our  emphasis will be on three concepts of chemistry in this Olestra unit. 

We will see how researchers used these simple chemical concepts to invent and develop olestra and we will use these principles ourselves to evaluate and decide on nutritional issues

Micro/Macro
and Symbolic
Representation

Here we represent the approach of two molecules to each other with a graph relating the distance between the molecules and their energy.

  We must understand this is a 2-dimensional symbolism of two microscopically small entities impacting against each othter with and without the presence of an enzyme clinging to one of them.

We can represent that impact itself as shown here:

Original Path

Two moving molecules strike each other with enough energy to deform/alter each other and they proceed to rearrange electron distributions so that a new bond, a new molecule forms

An enzyme bonds to one or more of the reacting molecules and deforms the shape.  Specific enzymes lower the energy for specific molecular changes to take place:

Enzyme Catalyzed Path

Recognize we are symbolyzing the microscopic mechanism or pathway of reaction; we recognize that we see the macroscopic result of the enzymatic reaction when we derive energy from our body's metabolic processes.

Mini Outline
Lipids- definitions and examples
Nomenclature and Edible Fats
Saturated and Unsaturated Fats and Associated Properties
Trans Fatty Acid Concerns

Lipids - Definitions and Examples: Lipids are biomolecules that are insoluble in water and highly soluble in non-polar organic solvents such as ether, chloroform, and benzene. Lipids perform many important roles. They are the highly concentrated fuel reserves that reside mostly in our adipose tissues. They constitute the bulk of biological membranes, forming an impermeable yet flexible barrier for all of our cells. As certain hormones and hormone receptors, they are signal carriers. They also form certain vitamins.

There are two general types of lipids. Complex lipids include fats, oils, and waxes that contain an ester linkages that can be hydrolyzed to smaller molecules.

Simple lipids such as cholesterol and other steroids do not have the ester linkages and cannot be hydrolyzed. In this Chemcase we will focus on the chemistry of the edible fats and oils, both natural and synthetic, and the similarities that these share with the fat replacement molecule, Olestra.

Nomenclature and Edible Fats: The edible fats of interest are called triacylglycerols or triglycerides; they are triesters of the glycerol molecule with three fatty acid chains

The fatty acid chains are always unbranched and typically not of the same length or number of carbon atoms. The individual fatty acid chains are named on the basis of the number of carbon atoms and whether the carbon atoms are joined by single bonds (saturated fatty acids).  

Fatty acids with one or more double bonds are called mono and polyunsaturated fatty acids. The fatty acid that is possibly the most common natural fat and makes up about 80% of the Olive oil that we enjoy has the common name of Oleic acid.

One systematic name for oleic acid, , cis-9-Octadecenoic acid is a bit less ambiguous. Let’s look at this name in some detail to understand how fatty acids are named. The Octadecenoic portion of the name tells us two things, that there are eighteen carbons in the chain and that there is one carbon-carbon double bond due to the -enoic ending versus the –oic given to the straight chained fatty acids with no double bonds. The cis portion of the name indicates that the carbon atoms adjacent to the double bond are located on the same side of the carbon atoms in contrast to the trans configuration, where the adjacent carbons are on opposite sides of the carbon-carbon double bond. Cis and trans isomers are called stereoisomers.

Lastly, the 9 indicates that the double bond occurs between the 9^th and 10^th carbon atoms and the acid portion indicates the presence of the carboxyl (COOH) group. Almost all naturally occurring fats are of the cis configuration, while the partially hydrogenated oils that are ubiquitous in our processed food society contain fats of the trans configuration. There is currently some controversy regarding the safety of these trans-fatty acids and we will look at this in a moment.

Saturated and Unsaturated Fats and Associated Properties:  All of us can recognize the many differences in properties of the different fats and oils, but how do these differences arise? Butter forms a solid stick and olive oil a semisolid in our refrigerator while the same olive oil is a liquid at room temperature. Corn oil remains a liquid at lower temperature, but the margarine that is made from "100%" corn oil (plus a little hydrogen) comes in a stick or in tubs as a less saturated form. Let’s look at how these differences relate to types of fatty acids present in some common edible fats.

Saturated Fatty acid content (%) Unsaturated Fatty Acids (%)

As shown in the table above, the animal fats have a larger % of saturated fatty acids while the vegetable oils have a greater portion of unsaturated fatty acids. The higher melting points of the solid animal fats are due to the fact that the saturated fats have straight chains and the molecules can pack together more closely

The vegetable oils contain more of the mono and polyunsaturated fatty acids which, due to their bends and kinks, cannot pack as tightly. The process of hydrogenation of fats and oils involves a partial hydrogenation of the carbon-carbon double bonds, thereby straightening the geometry of the fatty acid chains and raising the melting point of the blend.

This hydrogenation of oils is not done merely to change the room temperature consistency. The mono and polyunsaturated fats (PUFA’s) are unstable at room temperatures and the carbon-carbon double bond is reactive to heat, light and oxygen. This sensitivity increases with increased amount of PUFA’s and results in rancidification of oils. An extreme example of this oxidation process is with linseed oil; the oil is so high in PUFA’s that it quickly dries hence its use in oil-based paints.

When an oil or fat becomes oxidized or rancid a much greater health concern is the potential production of free radicals, which can be highly carcinogenic. One method of preventing this oxidation is by adding antioxidants which protect the weak double bond site. Vitamin E, beta-carotene, and the chemicals BHA and BHT are commonly used in this capacity. The other method is to hydrogenate these oils by adding hydrogen while using a catalyst (usually nickel) at elevated temperatures and pressure. The results of this hydrogenation are mixed; the oils become more solid and stable, but the cis conformation is usually replaced by the production of trans fatty acids

Trans Fatty Acid Concerns:  A Significant health concern in our society today is coronary heart disease, including atherosclerosis. Limiting total dietary intake of fats and cholesterol are viewed as significant factors in reducing the potential for heart disease, as well as a strong genetic control. After a brief summary of how cholesterol travels through our bodies, we will look at the trans fatty acid- cholesterol connection.

Cholesterol studies abound.  Cholesterol is first synthesized in our liver. When it travels through our bloodstream, it is in the form of lipid-protein globules. These can be low-density lipoproteins (LDL’s) or high-density lipoproteins (HDL’s). The LDL’s, which are the variety initially synthesized in the liver, are said to be "bad cholesterol" because they form the arterial plaque. The HDL’s, which transport the cholesterol back to the liver, are said to be "good cholesterol" because they can help remove some free cholesterol produced by dying cells, and may actually help scavenge plaque that has been deposited on the walls of our arteries. When the cholesterol is returned to the liver, either in the form of HDL’s or LDL’s, Protien receptors absorb the lipoproteins and the cholesterol recycling process begins again. There are two situations where this normal liver function is upset, one from a genetic inheritance, one from cholesterol rich diet. In individuals suffering from familial hypercholesterolemia (FH), the liver lacks the lipoprotein receptors that process the cholesterol, and the individual can have serum cholesterol levels nearly four times the recommended level, often resulting in childhood heart disease.

When people eat diets high in cholesterol, these cholesterol molecules help to "fill up" the lipoprotein receptors and this limits their capacity to maintain the normal cholesterol recycling process in the liver, again resulting in elevated serum cholesterol levels and associated health problems. Rare individuals possess abundant lipoprotein receptors and they can consume a cholesterol rich diet but still maintain a low serum cholesterol level. An important factor in this delicate balance is the ratio of "good" and "bad" lipoproteins, and this is where trans fatty acids are of some concern.

Dr. Alberto Ascherio summarized research on trans fatty acids and coronary disease in 1999.   He writes, "Metabolic and epidemiologic studies indicate an adverse effect of trans fatty acids on the risk of coronary heart disease.  Furthermore, on a per-gram basis, the adverse effect of trans fatty acids appears to be stronger than that of saturated fatty acids."   Apparently trans fatty acid consumption can have a depressive effect on the "good" lipoproteins without improving or lowering the total serum cholesterol levels. While more basic research appears necessary, it seems prudent to at least follow the American Heart Association guidelines which recommends the use of liquid oils for frying and the softer, tub margarines as spreads in order to limit the intake of trans fatty acids. Some individuals, such as Dr. Andrew Weil, recommend the use of a minimal amount of butter, and feel it is prudent to avoid the consumption of all trans fatty acids. The FDA has begun thinking about labeling foods as to their trans fatty acid content. 

Now that we have looked at fats, oils, and cholesterol, let’s return the Olestra Concept Map and look at the olestra molecule, which was originally tested as a cholesterol lowering substance.