Re: Re: high fructose ads & about LA - PUFA and Mercur

[Guest guest]

,

> There is a lot more to how dangerous PUFA are than just the amount

> included in our diet. I think focusing on a number (4%) doesn't

> always make much sense when other factors can play a bigger role.

> For instance people who have any amount of mercury in their system

> will have higher rates of lipid peroxides because mercury is so

> reactive and will snatch the electrons right from the EFA's located in

> the cell membranes.

It seems to me that this is just an additional issue. It doesn't

change the importance of PUFA, but just means that mercury is also

important.

> This will result obviously in more lipid

> peroxides and less EFA's in our body and less formation of

> prostaglandins. The damaged lipids obviously then need to be replaced

> for the cells to work properly and you will need higher than 4% PUFA

> but if you don't get rid of the mercury the cycle of destruction will

> just continue.

I seriously doubt that mercury will cause you to need anywhere NEAR 4%

of your calories from PUFA. The critical thing here is that what you

need are DHA and AA. You need these at microgram levels, similar to

vitamins. If you do not have factors causing oxidative stress such as

mercury and you are not in a state of growth, pregnancy, or lactation,

your needs are probably infinitesimal. Will they go up if you enter a

state of oxidative stress? Yes. A lot? Probably. But you can go

from infinitesimal and near zero up a very, very, very large degree

and still not get anywhere near 4% of your calories.

The second thing to remember is that total PUFA suppresses

desaturation of PUFA. The estimate in my nutrition textbook is that

linoleic acid up to 1 or 2% or so will increase arachidonic acid

levels, and thereafter it makes no difference until you get up to 12%

or so, when it actually starts depressing levels of arachidonate. So

if you need more AA and DHA, you want high levels of those two fatty

acids, maybe in gram levels for a period of time, but you don't want

high total PUFA because you will suppress desaturation. Even if you

are getting enough AA, your source of DHA will probably also include

EPA. If you have lots of linoleic acid shutting down desaturation,

you won't be able to turn the EPA into DHA, which according to my

working hypothesis expressed in my PUFA report is exactly what you

want to do.

Moreover, oxidative stress hurts desaturation, lowering the level at

which total PUFA intake becomes useless and then counterproductive.

Chris