See this is the problem - that is the popular narrative, but it isn't quite true. They came out with a drug that raised HDL (torcetrapib) - more people died. The problem is HDL is not 'a thing' it is a class of things - there are over 100 sub types of HDL - some are correlated with good out comes - some correlated with increased heart disease. Yet what is most important is realizing that reading about good or bad on correlations can lead us astray - in these pathways - everything effects everything - just because something is correlated does not mean it is a causation. LDL of burn patients goes up - does that mean that the LDL caused the burn?

I think one's HDL level is mostly correlated with the amount of saturated fat in one's diet. (HDL goes up with increased dietary SFAT )

There is more than a little controversy regarding lipid rafts - could be part of a signalling pathway. .. anyway - the bodies response to a wound is to increase LDL - the weak correlation with CAD does not show causation - could just as well be the result of the injury.

There are about 16 drugs that lower LDL - but only one type has been shown to help with CAD: statins. I think it is likely statins work on the NO pathway - nothing to do with LDL - and the effect is very small. The fact that these other drugs don't work seems to falsify the cholesterol theory of CAD. (There is another bit - supposedly LDL enters the intima of the artery wall to do the damage - only no one has been able to show this actually happens - they have tried - failed studies mostly don't get published.)

I've tested myself for oxLDL - and have read extensively - turns out the level of oxLDL is mostly related to the amount of PUFA in the diet - (The double bonds in PUFA are more prone to oxidation - less stable than the bonds in SFAT - the kind of fat your liver makes).

We are quite a ways off of PN - but I'll give you one more - the PUFA fats - the ones we have been told are "heart healthy" are not! Ancel Keys was the guy pushing this - they did a hospital study - a true controlled study many years ago - the people on the PUFA diet had a higher death rate. (this was published in BMJ). This data was apparently hidden - apparently to avoid embarrassment? It was only in the last couple of years that the data was found and published. ( Ancel Keys is know for the '7 country study' only it turns out it was the 7 out of 21 countries - he cherry-picked the data).

Further - PUFA's will lower LDL but most probably by inducing inappropriate insulin sensitivity in adipose tissue - you get a lower LDL at the expense of gaining weight - all looks OK until free fatty acids go up - fatty liver disease etc. This is rather important - more than half of people in my age group have type-ii diabetes - are overweight or worse. High blood sugars are associated with a huge increase in cancer rates, lower quality of life etc. etc. The low level science is well understood - if the mitochondria burn PUFA it changes an ion ratio - and that changes insulin sensitivity. Only problem is unless your doctor is a biology nerd and reads these papers - he doesn't know about this...

In 1960 - few people in the US were obese - not until they started pushing vegetable oils. ( A correlation - but one that has been repeated in other countries as seed oils begin to be imported). The problem is that Linoleic Acid ( the predominant fatty acid in seed oils) has a 600-day half life. If someone changes their diet - they are not likely to see the effect for many years. The ungrounded narrative that plant oils are good for you, is actually seed oil marketing - and I think it has has hurt a lot of people.

I don't have any diabetes - my PN could be due to exposures to metals - but I think it is more likely an auto-immune or occult infection. (I know a lot about diabetes - my father was an ObGyn - they do glucose tolerance testing - the common fasting blood glucose only goes up after a lot of damage has already been done. )
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What if the IVIG helps with PN by reducing occult infection? What if there are other treatments that could also reduce infection and effectively stop the progression? What if the popular narratives are wrong? What do I have to lose? - the risk:benefit ratio of trying things seems reasonable to me.