Wednesday, August 12, 2009

Vitamin E and PUFA avoid the cruel twist of irony

You may heard that the amount of vitamin E that you need is proportional to your fat intake. This is some what true. It is related to Poly Unsaturated Fatty Acids (PUFA). Lets break down what a PUFA is:
  • Poly - this means more than one, in this case more than one double bond
  • Unsaturated - this means at least one double bond on a fat change (eg not completely saturated with hydrogen)
  • Fatty - means a length of fat!
  • Acid - the end of the length of fat as some other atoms that make it an acid, typically a carbon and two oxygen atoms.
Thus PUFA are basically long lengths of fats that have at least two double bonds.
One of the difficulties encountered in determining the amount of vitamin E needed by humans is that the dietary requirement is influenced to a large extent by other nutrients. In both laboratory animals and humans the primary determinate appears to be the amount of PUFA in tissues. Vitamin E is the bodies most important protection and the oxidization of PUFA.
What this means is that the higher the PUFA in tissue, the higher the need for vitamin E as vitamin E is very important to stop PUFA "going off" eg getting oxidized.
Over a period of time the PUFA content in the tissues reaches equilibrium with the dietary intake os that vitamin E requirement can be associated with the consumption of dietary fatty acids. Although it is clear that a higher dietary intake of PUFA increase the demand of vitamin E, an exact quantitative relationship between these factors has not been established.
Great, we know we should have a higher intake of vitamin E, but don't know exactly what level. I should point out that most people, myself included, have no idea about our PUFA intake!

In a cruel twist of irony people at risk of heart disease eg high cholesterol, are advised to increase their intake of PUFA. However in doing so they need more vitamin E. Unless they have this vitamin E the PUFA will oxidize. It is the oxidization of the PUFA which is the root cause of heart disease. So all you on a higher PUFA diet to get your cholesterol down could well be increasing your risk of heart disease.

So if you are increasing your PUFA intake, you need to also increase your vitamin E intake.

Reference: Shukla, V., Dietary essential fatty acids and antioxidants. Lipid Technology vol2 no 1 1990 pg 14

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