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I am trying and failing to understand the topic of good and bad cholesterol and how it relates to diet.

It is still common wisdom, that LDL is to blame for artery calcification and resulting coronary vascular diseases.

However in recent times, there have been opposing views to this concept, some of which lay the blame on carbs and insulin resistance, rather than LDL.

In a video I watched recently it is suggested, that insulin response to glucose is a very strong predictor of cardio vascular problems. It seems, with a stronger correlation than LDL.

How strong is the evidence to support this hypothesis and is this incompatible with the common "house doctor" wisdom, that not carbs, but dietary fat is the problem and not insulin response, but LDL is the relevant marker?

For reference: https://www.youtube.com/watch?v=UZoQiDaWnuE&feature=youtu.be&t=985

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    Youtube isn't a great reference and I don't expect anyone to sit through a video to answer your question. I think you are both overstating the role of LDL as "common wisdom" and understating the very well known connection between diabetes and CVD. However, you also seem to think there is one cause of CVD and it's sort of a zero-sum game between different risk factors, which it is almost certainly not. – Bryan Krause Jul 26 '19 at 18:03
  • Comments are not for extended discussion; this conversation has been moved to chat. – Carey Gregory Jul 30 '19 at 2:10
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In summary, there is a strong evidence to say that the risk factors for cardiovascular disease (CVD) include:

  • High LDL-cholesterol
  • Insulin resistance
  • High saturated/unsaturated fat intake ratio and high trans fat intake
  • High intake of refined carbohydrates

High LDL-cholesterol and CVD

The Role of Lipids and Lipoproteins in Atherosclerosis (Comprehensive Free Online Endocrinology Book, 2019):

Population studies have demonstrated that elevated levels of LDL cholesterol and apolipoprotein B (apoB) 100, the main structural protein of LDL, are directly associated with risk for atherosclerotic cardiovascular events.

Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel (European Heart Journal, 2017):

Consistent evidence from numerous and multiple different types of clinical and genetic studies unequivocally establishes that LDL causes atherosclerotic cardiovascular disease.

Insulin resistance and CVD

Association between insulin resistance and the development of cardiovascular disease (Cardiovascular Diabetology, 2018):

Overall, insulin resistance contributes to generate CVD via two independent pathways: (1) atheroma plaque formation and (2) ventricular hypertrophy and diastolic abnormality. Both effects lead to heart failure.

Insulin resistance can also alter systemic lipid metabolism which then leads to the development of dyslipidemia and the well-known lipid triad: (1) high levels of plasma triglycerides, (2) low levels of high-density lipoprotein, and (3) the appearance of small dense low-density lipoproteins. This triad, along with endothelial dysfunction, which can also be induced by aberrant insulin signaling, contribute to atherosclerotic plaque formation.

Dietary fat and CVD

A systematic review of the effect of dietary saturated and polyunsaturated fat on heart disease (NMCD, 2017):

It is not total fat intake or saturated fat intake but high saturated/unsaturated fat intake ratio that is a risk factor for cardiovascular disease.

Reducing saturated fat and replacing it with carbohydrate will not lower CHD events or CVD mortality although it will reduce total mortality. Replacing saturated fat with PUFA, MUFA or high-quality carbohydrate will lower CHD events.

(CHD = coronary heart disease; CVD = cardiovascular disease, PUFA = polyunsaturated fattty acids, MUFA = monounsaturated fatty acids)

Trans Fats and Cardiovascular Health: Dr. Mozaffarian’s Testimony (Harvard.edu, 2006):

In large studies involving over 140,000 participants, trans fat consumption is consistently associated with increased risk of coronary heart disease.

Dietary carbohydrates and CVD

Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion (Nutrients, 2018):

It is not high-carbohydrate intake but high intake of refined carbohydrates that can increase the risk of cardiovascular disease.

The evidence linking carbohydrate-rich foods with CHD has been steadily strengthening. Refined carbohydrates, especially sugar-sweetened beverages, increase the risk of CHD. Conversely, whole grains and cereal fiber are protective.


The relatioship between insulin resistance, high LDL and cardiovascular disease (CVD):

  1. Insulin resistance can increase LDL, which is a risk factor for CVD, but not all individuals with insulin resistance have high LDL levels. On the other hand, high blood glucose alone, in the absence of high LDL can be harmful for arteries.
  2. High LDL levels can appear in the absence of insulin resistance, for example, due to high saturated/unsaturated fat intake ratio, high trans fat intake, obesity and genetic factors (CDC.gov).

So, it may not be necessary to think, which factor- insulin resistance or high LDL - is a better predictor of CVD - they are both important and may or may not be dependent from each other.

| improve this answer | |
  • Is it fair to say, that insulin resistance is, among other things, basically the cause of high ldl? So the better predictor obviously should be insulin resistance? – user1721135 Jul 27 '19 at 20:44
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    @user1721135, insulin resistance and high LDL are both risk factors for atherosclerosis and CVD and can act independently from each other, so I don't see the need to say which is more important. I added one section at the end of my answer. – Jan Jul 29 '19 at 10:20

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