PUFA Conversion Ratio Confusion

[rob]

Hi there,

I see a lot of comment about reducing PUFA intake, especially from veg oils. However, what has always confused me is that I thought the conversion of linoleic acid (from veg sources) to arachidonic acid - and subsquent downstream pro-inflammatory molecules - was extremely poor.

In this light, wouldn't PUFA (in the form of arachidonic acid) from animal sources be more deleterious? Moreover, unlike plant-based sources, wouldn't the PUFA issue from animal food be compounded by the lack of naturally-occuring vitamin E to counteract lipid peroxidation?

I always get confused by PUFA discussions. The whole thing about balancing omega 3:6 ratios always seemed odd to me because articles don't account for the poor conversion of linoleic acid and alpha linoleic acid into LA, and EPA and DHA respectively. For example, balancing 4g of linoleic acid from veg sources with 4g of omega 3 from oily fish is daft as the fish is providing far more potent downstream metabolites - it's not comparing like for like at all.

Anyway, I would appreciate others thoughts on the first bit as I know Ray Peat is very critical of PUFAs and urges us to limit them.

Many thanks in advance,

Rob

 

[Cirion]

I wouldn't stress necessarily the source so much as the total intake period - ie, limit all pufa's, plant, animal, oils or otherwise.

More intelligent posters may be able to answer your linoleic acid conversion question better than me.

And yeah, someone posted the other day a study that showed that omega 3 fats actually increase ROS by a factor of 2-3x over baseline, so they are also not good. Mainstream nutrition is on the right track in demonizing omega 6's, but the more interesting ratio is SFA:PUFA that most of mainstream nutrition doesn't focus on because they think SFA are bad also.

Yes VE can counteract the effects of PUFA to a degree, but as far as I know VE can not negate the effects, so if it comes to a choice, its still probably best to avoid the PUFA in the first place. But, supplementing VE can be helpful in the scenario where it is not possible to avoid PUFA for whatever reason and/or you are trying to lose body fat which will expose you to PUFAs.

 

[rob]

Hi Cirion,

Thanks for replying so quickly.

I already have a reasonably low PUFA as I’ve never been keen on veg oils. However, in order to get enough calories it would be good to know what of the foods left are better and worse offenders. For example, avocados (high linoleic acid but vitamin E to compensate a bit) versus, say, eggs or chicken (arachidonic acid).