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HDL

High-density lipoproteins (HDL) carry cholesterol from your blood to your liver. Within limits, higher levels of HDL cholesterol (HDL-C) are associated with a lower risk of cardiovascular disease (CVD), which is why it is often called the “good cholesterol”.

Our evidence-based analysis on hdl features 89 unique references to scientific papers.

Research analysis led by and reviewed by the Examine team.
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Summary of HDL

HDL-C and heart disease

High-density lipoproteins (HDL) remove cholesterol from arteries and plaques, protect the endothelium from damage, and inhibit LDL oxidation.[1] 

HDL basically does the opposite of LDL. While calling HDL-C “good cholesterol” and LDL-C “bad cholesterol” is simplistic, studies do show that a lower ratio of HDL-C to LDL-C (and of HDL-C to total cholesterol) leads to a higher risk of cardiovascular disease (CVD). Those ratios matter more than your absolute numbers for HDL-C, LDL-C, and even total cholesterol.[2]

HDL-C and apoA1

A WHO meta-analysis reported that eating more saturated fat increased HDL-C, but the increase was one-tenth that of LDL-C. Therefore, the ratio of LDL-C to HDL-C (and of total cholesterol to HDL-C) increased,[3] and with it the risk of heart disease.

A similar pattern was seen with apoA1, the major protein component of HDL particles, akin to apoB for LDL particles. Although replacing unsaturated fat by saturated fat led to increases in apoA1, the increase was only 30–60% that in apoB.[3] The ratio of apoB to apoA1 is considered a better predictor of heart-disease risk than other blood lipid biomarkers and their ratios.[4][5] If apoB increases more than apoA1, then the apoB-to-apoA1 ratio increases, and with it the risk of heart disease.

The HDL-C and apoA1 numbers reflect the amount of HDL in the blood. HDL has cardioprotective effects, but while eating saturated fat (instead of unsaturated fat) increases both HDL-C and apoA1, it increases LDL-C and apoB even more.

HDL-C and triglycerides

The ratio of triglycerides to HDL-C represents a strong, independent predictor of heart disease when LDL-C levels are below 160 mg/dL,[6] and has similar predictive ability as LDL-C for determining the extent of atherosclerosis in at-risk patients.[7] Having a ratio of triglycerides to HDL-C above 3.8 is associated with having more small, dense LDL particles, which are especially susceptible to oxidation.[8]

The aforementioned WHO meta-analysis reported that eating more polyunsaturated fat reduced the ratio of triglycerides to HDL-C, whereas eating more carbohydrate increased it, when saturated-fat intake was reduced.[3] However, the changes were very small and not clinically significant. A 10% reduction in calories from saturated fat would increase the ratio of triglycerides to HDL-C by a mere 0.16 if more carbohydrate were eaten, and decrease it by only 0.04 if more polyunsaturated fat were eaten.

The ratio of triglycerides to HDL-C correlates with the number of small, dense LDL particles and represents a strong risk factor for heart disease. However, changes in saturated-fat intake have little effect on this ratio.

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Human Effect Matrix

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The Human Effect Matrix looks at human studies to tell you what supplements affect HDL.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Supplement Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-a Notable Very High See all 14 studies
Garlic supplementation tends to increase HDL cholesterol in persons with cardiovascular disease risk reliably and in the range of 10-15% when looking at individual trials and by 1.49mg/dL (95% CI of 0.19-2.79mg/dL) as assessed by meta-analysis.
grade-a Minor Very High See all 27 studies
Mixed evidence, but a possible increase in HDL-C is seen with fish oil supplementation in unhealthy persons
grade-a Minor Low See all 25 studies
Overall, there appears to be a small increase in HDL, which is more effective in those with obesity and healthy participants as opposed to those with diabetes and kidney disease. There seems to be a greater effect for females but this is only based on a handful of studies.

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Frequently Asked Questions and Articles on HDL

Is saturated fat bad for your health?
Saturated fat is not inherently harmful. Compared to carbs and unsaturated fat, it has been linked to an increase in some risk factors for heart disease, but not directly to heart disease itself. As usual, by focusing on a nutrient in isolation, we risk missing the bigger picture: what matters most is your overall diet and lifestyle.
Will eating eggs increase my cholesterol?
Eggs increasing cholesterol depends on your genetics. They don't seem to increase the risk of heart disease unless you have a poor diet.

Things to Note

Also Known As

HDL-cholesterol, HDL-C

Click here to see all 89 references.