invert_nexus said:
Sam,
What you say about trans fats being dangerous because of their difference in shape to cis fats makes sense, however, why would these trans fats build up to dangerous levels when intake of cis fats outweighs the intake of trans fats by at least a factor of 6 (as stated in the FDA report concerning saturated fat)?
Also, there are natural trans fats in cow's milk as well as other sources that do not seem to have the unhealthy side effects ascribed to hydrogenated vegetable oils?
Another thing that bothers me is why are hydrogenated vegetable oils so bad? Maybe I'm forgetting something I've already read or that you've already gone on over here (it's early), but wouldn't the unhydrogenated versions of these oils also be trans fats?
Are they simply not dangerous because they're not used or not used as much? The hydrogenation process doesn't transform cis fats to trans fats, does it?
There's an article in the 15th September Science on the role of fatty acids in liver regeneration. Haven't managed to make it all the way through yet. Seems interesting. Unintuitive, to a layman, at least.
Its all relative.
How much total fat would you normally consume?
In a primitive diet with fruits, seeds, nuts?
Barely 10%, If you added meat at the most, (if you ate a lot of lard), 20-30%.
Right now our LOWER limits are set at 30%.
Ideally fat intake should be less than 30% with less than 10% of it from saturated fats.
There is a balance between the amount of omega-6 and omega-3 in the body.
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=12442909&dopt=Abstract
What we have done is exponentially increased the consumption of omega-6 (present in seeds) and decreased the omega-3 (present in stems and marine oils).
So the balance is already awry.
Naturally occurring fats are liquid or semisolid at room temperature and contribute fluidity to plasma membranes. The unsaturated bonds are essential parts of their structural functionality ( the membrane mosaic, they hold different membrane proteins in configuration). One would hypothesise that changes in structure would inevitably lead to changes in function.
Naturally occuring trans fats in cows milk are not so "naturally occurring" since fatty acid compostion of milk reflects fatty acid composition of feed. So its all down to our manipulation of the system actually. Just like us, cows also ingest trans fats through manufactured feeds enriched with hydrogenated fats.
edit: as to the adverse effects of trans fats, since they are functionally different from cis fats they may not be got rid off as easily and may accumulate over time, since, as I said, it takes long term intake to see adverse effeects. All processing of fats (including lipolysis, which gets rid of it) is defined by structure.