Molecular Fragments: Olestra

Site and models created by Dr. Dave Woodcock, Associate Professor Emeritus, UBC (Kelowna).

Copyright 1996, 1997, 2008 Dave Woodcock
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I. Olestra


Olestra image

Olestra is a fully esterized (see below) sucrose (common sugar) molecule developed by Proctor and Gamble at an estimated cost of $200 000 000. The ester shown in the model is the octaoleate ester. This molecule is so structured that the enzymes in the digestive system, in contrast to the case for the natural fats (see below), cannot reach the ester links (showing red on the model - the colour for oxygen) located close in to the central rings of the sucrose . The molecule is thus not digestable and passes through the body unchanged. The the fat-like constitution of the compound, and its indigestability, makes it a non-caloric fat substitute.

A physical chemistry problem:
Since the compound is water-insoluble, it will tend to form a suspension in the aqueous digestion tract and provide a non-polar environment for dissolving (extracting) other water-insoluble compounds (the 'like' dissolves 'like' principle) such as Vitamins A, D, E and K, thereby carrying them through and out of the body (see for example: The Olestra Project).

Olestra seems to have other problems associated with it. Some sites on the web concerned with the 'pros' and 'cons' of Olestra are:
The Facts About Olestra
Information About Olestra, Diabetes Monitor
Olestra: The Facts, from Frito Lay

II. A Natural Fat


Fat image

This second model is of a typical fat substance. Noteworthy is the difference in size leading to easier access for enzymes to the ester links (again in the red of the oxygens). Natural fats and oils with this structure are broken down by the digestive enzymes: the fat is utilized by the body as an energy source.

III. The Constituants of Olestra and Fat

Esters are formed when an alcohol group (-OH) reacts with an acid group (-COOH). In the models below the -OH groups are easily seen as red (oxygen) linked to white (hydrogen), the -COOH group is the site on the acid with the red oxygens.

For olestra, the alcohol groups are part of the sucrose molecule. Look closely and you will find eight such groups.
For natural fats and oils, the alcohol groups are part of the glycerol molecule. In this case there are only three such groups in the molecule.


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Stearic Acid
Octadecanoic Acid

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