I have low cholesterol, about 2.3 when last tested. Why? No idea. Not a vegan; have butter, cheese, eggs, meat and so on, though little milk. Also have low salt levels, why? No idea, even finished up in A&E once because of it.
I've been reading Professor Tim Spector's book, the Diet Myth. He tells a simple story against himself.
At the end of the his medical studies he wrote an academic paper linking coffee drinking with certain cancers. It did wonders for his CV and apparently got him a Research post and much success.
Years later he realised the increase in cancers also correlated with increased sales of flared trousers and TV's. The mantra in all research is, 'correlation is not causation'. One of the joys of threads like this are that there's always a piece of research that says the opposite.
Spector, by the way, would attribute my low cholesterol to genes or bacteria.
For those of you who are busy, no need to read further as I've made my point.
Being 80 and more time on my hands than most of you I checked the McDougall research paper posted early on in this thread by OP. McDougall is an American Vegan MD.
The paper describes an uncontrolled study and therefore cannot be certain its conclusions can be translated for wider use.
Diet by participants before the trial is not described but if they were eating the stereotypical US food then it's not surprising that any reduction in just the amount of food. would make a difference.
This trial, and a similar one by Eselstyn, make no mention of other parts of their lifestyles, smoking, drinking and alcohol or exercise for example.
Also, I checked one of the references – war time in Denmark. There are similar papers for Norway, oft quoted by vegans.
Certainly, all occupied countries, as well as UK, suffered food deprivation particularly in terms of Germans exporting meat products to their home country. Recorded diseases went down but we have no way of knowing how far food consumption was effected. In Norway fish consumption went up by 200%, meat down by 60%. I'm tempted to conclude it was fish, not plants that reduced some diseases.
The Denmark paper is actually based on Copenhagen, not the whole country; the world over large cities suffer at times of food shortages far more than the countryside. I was born in London, moved to the countryside 1965 and was shocked at how much people boasted about the black market in food during the war. City experience may not be relevant.
I believe the general consensus is UK citizens were generally healthier during the war, despite bacon and eggs.
Oh, if you like dark chocolate and red wine, Spector is on your side.