Milkfat

Studies have failed to consistently confirm that dairy fat is bad for you, with some suggesting that it's good for you.

Article suggests that butter is probably still bad for you (it's just all saturated fat) but there's scant evidence for that either.  (I've cut out butter, but I daily consume several teaspoons of cream--which I think is healthier and tastier.  All the rest of my considerable dairy intake is non-fat.  I use olive oil for all other purposes.)

It was saturated fat from meats which is the troublesome one.  But the harm of that has probably also been overstated.

Sugar and it's disorder Metabolic Syndrome (Type II Diabetes) are leading factors in the research I have seen.  Sugar is not going to be proven healthy, except in tiny amounts promoting hydration (which is healthy).  The Sugar industry funded the research that led to blanket condemnation of saturated fats, which are typically a secondary concern.  This led to a generation of low-fat products with extra sugar and soaring diabetes.

I'd call into question the entire HDL/LDL cholesterol theory too.  Research I've seen suggests these are fairly unimportant, and insignificant for people over 65.  And yet, there's now a whole industry related to this, at least two of my senior friends with very healthy diets are statin taking statin drugs.  (I took statin drugs for 15 years while I was still working and eating very unhealthy amounts of fat and sugar and not getting enough exercise either.  In those conditions, statins could be marginally helpful overall, I believe now, but probably not others).  I see this as an example of over-medication.  Older people actually need to consume more fat (also protein and calcium) per kg of body weight for regular body maintenance because it's used less effectively.  Old people have a strong tendency to get too thin and weak because they don't bear this in mind.

People imagine heart disease as a simple accumulation of fatty stuff eaten, but that's not at all the case.  Some with the highest saturated fat intakes may have the least issues.  It seems most likely now that heart disease is some sort of regulatory failure or autoimmune disease and may be related to subclinical infections that flourish in the environment of sugar, metabolic disease, and stress, with fats being only of secondary or tertiary importance.

It's easy to find lots of correlations around the illuminated lamp pole of things you can measure easily.  Especially when there are areas like sugar and stress that are blacked out by the Sugar Industry and Capitalism.