@HairySmurf I thought that recent views were that LDL levels are not a good measure of risk per se, but the types of LDL and also the ratio of total cholesterol to HDL.
@KennyA Encouraging list of highlights for those who eat relatively high fat diets.
I have a relatively high total cholesterol but so far the ratios have been good and the surgery seem happy with that.
I have seen it suggested that higher cholesterol may be a benefit to older people, especially women.
The gold standard test is for apolipoprotein B (ApoB) which is a protein on the surface of each 'bad' particle in the blood. That test gives you an approximate count of how many problematic particles are actually in there. It's better than the commonly-available tests as the count of particles is more important than how much cholesterol is actually in the blood. Measuring cholesterol isn't ideal as a lot of small LDL particles might show a similar result to a smaller number of larger particles. It's not the amount of cholesterol in the blood that matters but the number of individual particles in circulation banging into the artery walls over a lifetime. Unfortunately the ApoB test (in Ireland at least) is only offered to people who are known to have heart problems. It's only available privately here and it's not cheap.
The next best thing is the 'Total minus HDL' figure (non-HDL cholesterol) - total cholesterol in the blood which isn't contained in a HDL particle. This is roughly equivalent to Apo-B in most cases (
Link) and is as good an indicator as most of us have access to.
The next best indicator is LDL. There are problems with this though as LDL is calculated based on the other measurements, not measured directly, and as mentioned above there might be lots of small LDL particles or a smaller number of larger ones which can make a big difference to the actual risk involved.
The 'Total to HDL' ratio has been discredited as a good indicator. HDL is known marker for metabolic health and for a good diet but when medications that artificially raise HDL were developed and tested in clinical trials they had no detectable effect on health outcomes. Thus by taking one of those meds a person's ratio would look very good while it wouldn't actually do anything. Why exactly high HDL is associated with good heart health is still being investigated but the ratio is now seen as the least valuable indicator of those listed above. It still appears on blood test results though, still used by the QRisk3 calculator, still taken seriously by many doctors, which says a lot about how far behind the times a lot of the testing and general knowledge around cholesterol is (even amongst many GPs).
The information above comes from a series of interviews with lipidologist Dr. Thomas Dayspring - knows his stuff, lectures doctors about cholesterol, rated amongst the top doctors in the US. Interview series linked here -
Link. When watching those interviews I noted down the relationship between the different indicators and Dayspring's recommendations as to what levels a person might want to aim below (he talks about it in video 3 I believe). I haven't found any similar resource elsewhere and there's a chance I noted something down wrong here so take these figures with a grain of salt - this is the word of one doctor interviewed on YouTube:
LDL-C
2.59 mmol/L (100 mg/dL) - for the general population
1.81 mmol/L (70 mg/dL) - for those at increased risk
1.42 mmol/L (55 mg/dL) - for those at high risk
Non-HDL-C
3.36 mmol/L (130 mg/dL) - for the general population
2.59 mmol/L (100 mg/dL) - for those at increased risk
2.2 mmol/L (85 mg/dL) - for those at high risk
Apolipoprotein B
100 mg/dL - for the general population
80 mg/dL - for those at increased risk
65 mg/dL - for those at high risk
60mg/dL - aggressive treatment for people at very high risk
The reality is these levels are guesses to some extent, just like every cholesterol recommendation provided everywhere - they're very round numbers that approximate something that is unique to the individual. We can't actually know how far along the path to heart disease we each are without advanced testing which is not available to most of us. In my case, a person who was a smoker for 20 years, was obese for much of that time, did not exercise enough, was diagnosed diabetic (and so was likely on the path to that for years) and likely continue to be insulin resistant I see myself as somewhere between increased risk and high risk. For this reason I aim to achieve somewhere between 2.6 and 2.2 mmol/L on the 'Non-HDL' scale. I do pay attention to my HDL result but more as a general indicator that I'm eating well and getting enough exercise than as a target in itself to work hard at changing.