animal fats and EFA's (was: Re: Is pasteurized milk really bad?)

[Guest guest]

> >>>3. I have no idea which EFA's play a role in lactation, but

animal

> fats contain the long chain omega-3's and the bodies conversion rate

> from LNA to EPA/DHA is horrible (that delta-6 desaturase has

probably

> done in many vegans!) I have one study that shows a 6% and 4%

> conversion rate for EPA and DHA, and another that finds that only

> 0.2% of plasma LNA ends up as EPA or DHA.

>

> ***, animal tissue also contains LNA.

Sure. I'm trying to make the point that animal fats are the only

decent source of EPA and DHA. LNA can come from either.

>I There are factors that do interfere

> with conversion to longer chain FAs, but I have to think if it's

there, then

> we *should* be able to convert it.

Trans-fats can interfere with the D6D. But the fact that its there

does not mean the conversion will be efficient or that we'll produce

adequate amounts of the enzyme. If you have evidence suggesting that

we can, I'd appreciate the reference.

> Are the studies

> you mention online?

Only the abstracts, on medline. Here is the excerpt from my review:

*The plant based versions of omega-3 fatty acids are not biologically

active. Only 0.2% of the plant form (LNA) in blood plasma ends up

being converted to the " fish oil " forms found in animal products

(130). This trait is shared with other omnivorous and carnivorous

species and is a result of animal products being a staple in the

diet. Vegetarian species make the conversion readily.

* The absorption of omega-3's is increased substantially when

consumed with ample saturated fat(131)

* Fish are not the only source of " fish oils " . Grass-fed animals have

up to 10 times more omega-3 fatty acids, in the more beneficial " fish

oil " form, than grain fed animals(132). The same thing applies to

eggs from pastured chickens(133).

130. Pawlosky RJ, Hibbeln JR, Novotny JA, Salem N Jr. Physiological

compartmental analysis of alpha-linolenic acid metabolism in adult

humans. J Lipid Res 2001 Aug;42(8):1257-65

131. Lawson LD, BG. Absorption of eicosapentaenoic acid and

docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl

esters co-ingested with a high-fat meal. Biochem Biophys Res Commun

1988 Oct 31;156(2):960-3

132. Duckett, S. K., D. G. Wagner, et al. (1993). " Effects of time on

feed on beef nutrient composition. " J Anim Sci 71(8): 2079-88.

10. -Bote, C. J., R.Sanz Arias, A.I. Rey, A. Castano, B. Isabel,

J. Thos (1998). " Effect of free-range feeding on omega-3 fatty acids

and alpha-tocopherol content and oxidative stability of eggs. " Animal

Feed Science and Technology 72: 33-40.

Finally, lets take the " common sense " approach. Suppose animal fats

are a bad source of EFAs. But we know that all humans need EFAs, so

where do they get them? In primitive times cold water oily fish would

only be an option for the innuit. There are a couple seeds like flax

and a few others. However, in primitive times seeds are not a year

round food supply. Furthermore, what are the chances that all

primitive humans happened to live near a ready supply of flax or one

of the other rare high omega-3 seeds? Not likely.

So where do animals get their EFAs? Herbivores get them by eating

grass. Carnivores get them by eating animals/insects. I'm sure there

are a few niches of animals that got them through more exotic

sources - but those animals are probably also tied to a specific

locations with a specific food source.

Common sense tells me that humans got EFA's by eating animals and

insects. So common sense tells me that that's how we should continue

to get them. So the evidence and common sense neatly coincide.