[sradman]

PROBLEM #1: High saturated fat diet correlated to high serum cholesterol

ANSWER #1: Serum cholesterol is transferred back-and-forth between the blood and cell membranes to maintain a constant cell rigidity; normal behavior

PROBLEM #2: High serum cholesterol correlated to cardiovascular disease

ANSWER #2: Chronic inflammation associated with metabolic disorders upsets the various regulatory systems

I find the second answer unsatisfactory. Any chronic condition that damages arteries leads to plaque and this, in my opinion, accounts for all the other associations. The arterial wall damage can be due to excess blood sugar, oxidation, or pathogens (SARS-CoV-2?). The damage causes an inflammatory response and extra serum cholesterol is needed to repair the damage (forms the plaque). The chronic plaque formation reduces the arterial cross-section and reduces elasticity which both increase blood pressure.

The underlying cause is arterial wall damage. This can be measured non-intrusively using the Ankle-Brachial Pressure Index:

https://en.wikipedia.org/wiki/Ankle–brachial_pressure_index

[beowulfey]

I think it is more:

PROBLEM #2: high serum cholesterol is correlated to cardiovascular disease, but eating high saturated fat-diets is not.

ANSWER #2: It appears that studies that assess the effect of a particular diet depends a lot upon the health of the individual prior to the study start; thus, using a random population results in non-significant results.

Note that I agree with you otherwise. I would suspect that a diet high in saturated fats without any supplemental unsaturated fats would result in cell walls becoming so stiff that removal of cholesterol can no longer benefit the cell walls; if this happens in arteries, you get hardened arteries that can lead to heart disease.

[sradman]

My key takeaway is that the ratio of saturated:unsaturated fat in the diet does control the concentration of serum cholesterol but any ratio between 1:0 and 0:1 (provided you get enough essential fats) is perfectly normal and does not impact health negatively either way. The function of serum cholesterol is maintaining cell rigidity throughout the body, not just in arteries. I have never heard this explanation before; it makes sense. This claim should be easy to verify experimentally.

The question then turns to the underlying cause of atherosclerosis. The arguments, to me, seem circular. Ultimately, the important question is how much of the plaque is due to a damaging agent like sugar and how much is due to a hyperactive inflammatory response. Measuring inflammation independent of arterial wall damage seems incomplete.

[megameter]

Speaking anecdotally, I put a few logical ideas together from different articles and got an answer that seems to work for me some years ago:

1. Simple carbs like sugar are metabolic stressors

2. Saturated fats, as well as other agents like caffeine can act to accelerate the metabolisation of sugar

3. If you consume a stressor with an accelerator, you are more likely to do damage than if they are spread out or diluted e.g. with fiber, so don't do that

4. (Something something exercise)

This hypothesis, while lacking in rigor, explains why I can have two burgers and be fine, but be miserable if I have a burger, fries and a coffee.

[woeirua]

Problem #1 is not actually observed though. We know from many, many studies that dietary cholesterol is not directly correlated with serum cholesterol. The article even alludes to the point that the body regulates cholesterol on its own regardless of diet.

[brianjunyinchan]

On the different pathways that inflammation might lead to arterial wall damage, here is a good read:

https://harvardmagazine.com/2019/05/inflammation-disease-die...

[graeme]

> This can be measured non-intrusively by measuring the Ankle-Brachial Pressure Index

Huh. Is this something one’s GP could do or does it require specialized training? The article says it’s unpopular at general practitioner’s offices.

[jpxw]

Most GPs (or at least all GPs I’ve ever visited) don’t have ultrasound machines.

However I imagine they’d be able to perform a simplified version, just measuring the BP at the arm and the ankle and dividing.

Presumably using the ultrasound just allows you to get a more precise reading.

[sradman]

You can do it at home with a standard blood pressure monitor with an arm (brachial) cuff but not a wrist one. Ask your GP.