on February 21, 2010
at 11:03 AM
There aren't any strict rations suggested by the paleo approach, but since your main source of fat should likely be animal fat, you'd be looking at mostly SFA and MUFA with minimal PUFA, with the ratios of omega 3 to omega 6 within PUFA being more important.
Regarding PUFA, you need to get adequate amounts of the essential fatty acids (a very low amount) but, I would say, ideally no more than that. PUFA are more likely to oxidise and glycate, than MUFA or SFA. Cordain suggests relatively more PUFA and less SFA (though he's coming round on SFA) on the basis that he argues that paleo animals would have less SFA. Also conventional wisdom implies that SFA has its own downsides (whether coronary or via insulin resistance), whereas PUFA have been identified with lowering cholesterol (which is supposed to be a good thing; with the caveat that there may be no intrinsic value to lowering mere markers themselves and the fact that PUFA are more likely to produce oxidised (dangerous) cholesterol than SFA (which raises good HDL, and large, less dangerous cholesterol).
As to the merits of MUFA versus SFA. Some would argued that SFA is less reactive than MUFA and therefore superior and also the physiological insulin resistance of SFA might be a desirable adaptation. Others think that MUFA purportedly having less of a cholesterol-raising effect and not causing the same insulin resistance as palmitic acid would be preferable. One thing is certain, which is modern, conventionally-raised animals have more SFA-to-MFA than paleo animals. They're also fatter, though I think this is more than made up for by the fact that a whole carcass, including marrow, would provide more fat than modern cuts of meat. Typically, meat contains roughly equal amounts of MUFA:SFA, and dairy fat contains more SFA at around 2:1. I wouldn't think that anything even vaguely akin to a 1:1 ratio would be harmful and a lot of paleo people will consume relatively more SFA because of eating conventional meat or using dairy as a source of fat. Although there are various ways you might get relatively more SFA, there are few good ways of getting more MUFA (olive oil being ok, but relatively O-6y, and macadamia nuts).