What are the good and bad cholesterol ?

I have question about cholesterol, as I know we can get cholesterol using vegetables and meat, so what is good and what is bad ?

Original Answer (posted originally as a Comment)

It is now accepted that high cholesterol causes atherosclerosis. Cholesterol a major component of the plaques that block arteries. 'Good' and 'bad' cholesterol refer to the way cholesterol is transported in the bloodstream.

'Bad' cholesterol is cholesterol in the form of low density lipoproteins or LDL, and 'good' cholesterol is in the form of high-density lipoproteins or HDL.

Or at least that is how it used to be. It is still accepted that high concentrations of LDL in blood promote atherosclerosis, that is high levels of LDL may still be considered 'bad', but drugs that specifically raise the levels of HDL have had serious adverse effects.

Check out this great article: Cholesterol and Controversy: Past, present and Future by Jeanne Garbarino, especially the section on "Deconstructing Cholesterol: “Bad” is still bad, but is “good” still good?". It is hard to know what the current position is. And check out the work of Brown and Goldstein.


Goldstein, in his Nobel lecture, famously said (see here)

Cholesterol is a Janus-faced molecule. The very property that makes it useful in cell membranes, namely its absolute insolubility in water, also makes it lethal. For when cholesterol accumulates in the wrong place, for example within the wall of an artery, it cannot be readily mobilized, and its presence eventually leads to the development of an atherosclerotic plaque.

Cholesterol may be synthesized in the body, or obtained from the diet. The site of biosynthesis is mainly the liver. Cholesterol and fats (triacylglycerols) are transported in the bloodstream as lipoprotein particles, which may be roughly described as a lipid core surrounded by a protein coat, and may be viewed as a mechanism for transporting insoluble fat molecules (by 'coating' them with a soluble protein exterior).

There are five main classes of lipoprotein particles (see, for example, Berg): chylomicrons, very low density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL)

Cholesterol (and fats) are transported from the liver to other tissues in the form of low-density lipoproteins (LDL). High-density lipoproteins, on the other hand, pick up cholesterol and fats in the blood and from specialized cells and transport them to the liver. Hence the names 'bad' and 'good' cholesterol. (In reality, of course, things are more complex than this simple scenario: for a very readable account, see Berg).

The ratio of 'bad' to 'good' cholesterol, ie the ratio of LDL to HDL may be used diagnostically, and a healthy LDL/HDL ratio is about 3.5 (see Berg), but in view of the studies cited by Garbarino a low ratio due to high concentrations of HDL (rather than low LDL) might not be so great either. In fact, if LDL is in check, there may be no benefit to raising HDL (Garbarino article). But I suppose the physicians will always find a way to waffle (and to charge for the privilege).

It is a common misconception that plants do not contain cholesterol. (My original answer to this question attempted to promulgate this nonsense). In particular, plant membranes do contain cholesterol. However, the amount of cholesterol in plants is low compared to that found in animals (Behrman & Gopalan, 2005). But it is certainly not zero. The nucleus of maize shoots contain significant amounts of cholesterol, for example (Kemp & Mercer, 1968).

This great reference, Cholesterol in Plants, by Behrman & Gopalan (2005) suggests that the following paragraph should be inserted into biochemistry texts.

More than 250 steroids have been described in plants. Of these, perhaps sitosterol, which differs from cholesterol by an ethyl substituent at position 24, is the most common. But plants also contain cholesterol both free and esterified. Cholesterol occurs as a component of plant membranes and as part of the surface lipids of leaves where it is sometimes the major sterol. The quantity of cholesterol is generally small when expressed as percent of total lipid. While cholesterol averages perhaps 50 mg/kg total lipid in plants, it can be as high as 5g/kg (or more) in animals.

A great generalization is the following (Behrman & Gopalan, 2005)

Prokaryotes do not contain cholesterol

These authors also suggest that one of the reasons for the common misconception that plants do not contain cholesterol is "legalities of food labeling that allow small quantities of cholesterol in foods to be called zero".

I suppose we should not be too surprised that plants can make cholesterol. They can of course, make steroids, the Mexican yam being the original source of a precursor of a particularly important one.

A key enzyme in the biosynthesis of cholesterol is HMG-CoA reductase, which is the target for statins, and these drugs may be used to lower serum cholesterol levels (but there may be side-effects).

One interesting thing about the biosynthesis of cholesterol is that the final cyclization step requires oxygen which has lead to much philosophical and evolutionary debate (see, for example, here).

Finally, another quote from Goldstein

Cholesterol is the most highly decorated small molecule in biology. Thirteen Nobel Prizes have been awarded to scientists who devoted major parts of their careers to cholesterol. Ever since it was first isolated from gallstones in 1784, almost exactly 200 years ago, cholesterol has exerted a hypnotic fascination for scientists from the most diverse domains of science and medicine

The question as stated is unclear as to what is being asked.

If the question is whether ingested cholesterol from whatever source is good or bad, then the answer is that dietary cholesterol is superfluous to human nutrition since it can be synthesized by the liver, and the latest guidelines suggest to keep intake as low as possible.

While adequate evidence is not available for a quantitative limit for dietary cholesterol in the 2015-2020 Dietary Guidelines, cholesterol is still important to consider when building a healthy eating style. In fact, the Dietary Guidelines states that people should eat as little dietary cholesterol as possible. 1

The main source of dietary cholesterol is overwhelmingly from animal sources. A meta-analysis published in August 2017 of vegetarian diets found that

Of the 8385 studies identified, 30 observational studies and 19 clinical trials met the inclusion criteria (N = 1484; mean age, 48.6 years). Consumption of vegetarian diets was associated with lower mean concentrations of total cholesterol (−29.2 and −12.5 mg/dL, P < 0.001), low-density lipoprotein cholesterol (−22.9 and −12.2 mg/dL, P < 0.001), and high-density lipoprotein cholesterol (−3.6 and −3.4 mg/dL, P < 0.001), compared with consumption of omnivorous diets in observational studies and clinical trials, respectively. Triglyceride differences were −6.5 (P = 0.092) in observational studies and 5.8 mg/dL (P = 0.090) in intervention trials. 2

concluding that plant based diets reduced total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol ( as the latter is used in reverse cholesterol transport so with less circulating cholesterol there is naturally less to transport ) but triglycerides were unaffected.

So, if you eliminate animal based foods (and therefore the main source of dietary cholesterol) then the studies suggest you are likely to improve your lipid profile which is presumably one reason for the guidelines.


  2. Association between plant-based diets and plasma lipids: a systematic review and meta-analysis

Cholesterol Good and Bad

Cholesterol is found in all of our cells. Cells need it to keep their membranes just the right consistency.

Our body also makes things with cholesterol, like steroid hormones, vitamin D, and bile.

Here’s how cholesterol can be bad.

Cholesterol in the blood can stick to artery walls, forming plaque. This can block blood flow. Atherosclerosis is the condition where plaque narrows the space inside the artery.

Multiple factors can cause plaques to rupture, like inflammation. The body’s natural healing response to damaged tissue can cause clots. If the clots plug up arteries, blood cannot deliver vital oxygen.

If the coronary arteries that feed the heart are blocked, this could lead to a heart attack.

If the blood vessels of the brain or the carotid arteries of the neck are blocked, this could lead to a stroke.

If the arteries of the leg are blocked, this could lead to peripheral artery disease. This causes painful leg cramps when walking, numbness and weakness, or foot sores that do not heal.

So cholesterol can be good and bad. There are also different types of cholesterol sometimes called “good cholesterol” and “bad cholesterol”.

LDL, or low-density lipoprotein, is sometimes called “bad cholesterol”. It carries cholesterol that can stick to arteries, collect in the vessel lining forming plaque, and sometimes block blood flow.

HDL, or high-density lipoprotein, is sometimes called “good cholesterol”. It takes cholesterol away from the blood and returns it to the liver.

When checked, you want your LDL to be low. L for low.

You want your HDL to be high. H for High.

A blood test can measure the LDL, HDL, and total cholesterol. Usually, there are no visible symptoms of high cholesterol, so it is important to be periodically checked.

Ways to decrease your LDL and increase your HDL include:

  • Eating a heart-healthy diet low in saturated and trans fats.
  • Regular exercise and being more physically active.
  • Maintaining healthy weight.
  • Quitting smoking.
  • Medications. Medications might be recommended depending on known risk factors for cardiovascular disease (such as age and family history among others).

You may already be familiar with these guidelines for heart-healthy living. They are based on research supported by the National Heart, Lung, and Blood Institute (NHLBI) at the National Institutes of Health, or NIH.

This video was produced by MedlinePlus, a trusted source of health information from the US National Library of Medicine.

LDL Cholesterol

LDL cholesterol can build up on the walls of your arteries and raise your chances of heart disease. That’s why LDL cholesterol is referred to as "bad" cholesterol. The lower your LDL cholesterol number, the lower your risk.

If your LDL is 190 or more, it is considered very high. Your doctor will most likely recommend a statin in addition to making healthy lifestyle choices. Statins are medicines that can help lower cholesterol levels.

You may also need to take a statin even though your LDL level is lower than 190. After figuring your 10-year risk, your doctor will recommend a percentage by which you should try to lower your LDL level through diet, exercise, and medication if necessary.

Learn More

  • Cholesterol - what to ask your doctor (Medical Encyclopedia) Also in Spanish
  • Cholesterol Good and Bad />(National Library of Medicine) Also in Spanish
  • Cholesterol Levels />(National Library of Medicine) Also in Spanish
  • Cholesterol testing and results (Medical Encyclopedia) Also in Spanish
  • Niacin for cholesterol (Medical Encyclopedia) Also in Spanish


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I have lived a 19-20 years, with LAD stent and medical treatment:
which “Statins” cannot be over-emphasized. Presently, I am on
Rosuvastatin 10mg and over the few Lipid Profiles, including recent
one, has been reported as optimal numbers, LDL 76, HDL 64, TC 162, Triglycerides 131.

I had no idea there are so many non-medical experts until reading the above comments! We can certainly save a lot of money by not going to a medical doctor and, instead, consult with so many experts. Thank you for your expertise! I bet if anyone follows your advice and has any problems you can be sued and prosecuted for practicing medicine without a license. By the way, all stains are off patent! The last one to lose patent protection was Crestor and there are 5 generic makers on the market. So they are not the most expenses drugs on the planet!

High cholesterol is a marker of increased risk for heart disease, a sort of “canary in the coal mine” that tells you your system is out of whack, your diet is poor, or your sedentary lifestyle is putting you at risk for a cardiovascular event. When we lower cholesterol by prescribing statins we risk masking the symptom while patients may or may not follow through with lifestyle changes. Indeed, there is a real risk that some people may incorrectly assume because they are on the statin, they are safe continuing to eat a poor diet and not exercising. For these reasons, some docs question the value of statins altogether.

Please consider the full story next time you write about cholesterol and cholesterol reducing therapies.

This is over simplistic and a mediocre advertisement for “statins”. The most profitable and prescribed class of drugs on the planet. It’s a cash cow. You failed to list the horrific sides. I rather die of a heart attack at 60 than take a statin and risk dying now of rhabdomyolytis, liver damage or diabetes among others. Statins are for people with genetic issues related to cholesterol. Why does cessation of the smoking habit lowers cholesterol? Because it causes inflammation. Its the inflammation that is the problem. Take an anti histamine. Exercise is pretty good tho, but too much cardio is damaging. Go lift some moderate weights with a qualified trainer and look better and live longer. Stop eating junk.

The information presented and guidelines offered in this article have been contested successfully in recent times, to put it lightly.

Peter Attia and Thomas Dayspring’s work would be a good start to learn more. Please do. You owe it to your Harvard, Yale, MGH pedigree.

There’s definitely a lot to know about this issue. I really like all the points you made.

Interestingly, cholesterol is controlled by an enzyme, UBIAD1, that also controls calcium behavior and is essential to create the form of vitamin K2 that we make endogenously, Menaquinone-4 (MK-4).
We make MK-4 in tissues throughout the body from menadione (vitamin K3) that is transported there via the lymph system via this UBIAD1.
When CKD patients were given vitamin K2, their cholesterol levels dropped and then, when supplementation stopped, their levels renounded.
Messed up K status leads to weakened bones and ossified arteries, measured as CAC.
The best predictor of a cardiovascular event is CAC. This exceeds all the lipids measures into which cardiology has so invested.
A CAC=0 is a 15 year warranty from death by all causes.
Statins increase CAC.
Vitamin K2 is created from all dietary forms of vitamin K – K1 and all forms of K2 – but this isi mssed because of upstream mistakes surrounding cholesterol understanding.
Fermented full fat dairy is high in long chain K2, yet such as this diatribe would make it seem that reduced fat dairy has better health outcome.
This is incorrect the K2 is in the fats.
Organ meats are also high in long chain K2.
We have lost many foods high in K2, messed with K actions via bad dietary understanding, and toxic drugs and thus made folks have poorer K status which leads to more CAC, indicative of atheroscerosis.
This article is mainstream understanding, the mainstream narrative, but it is incorrect.
Search K2, UBIAD1, and learn these pathways.
Mainstream cardiology has led us astray.

Dietary Fats and Cholesterol Affect Your Cholesterol Levels

To improve your cholesterol levels, avoid or limit food sources of cholesterol and saturated and trans fat while choosing food containing fiber and unsaturated fats. Only animal foods contain bad fats and cholesterol plant foods and most fish do not. The Academy of Nutrition and Dietetics recommends eating 20 to 35 percent of your daily calories from mainly unsaturated fat while limiting saturated fat and avoiding trans fat altogether. The American Heart Association recommends keeping your cholesterol intake to less than 300 milligrams if you have normal cholesterol and less than 200 milligrams if you have high cholesterol.

Why is cholesterol important?

Despite its bad reputation, cholesterol is important for your health and it serves many purposes in the body.

Cholesterol helps your body make hormones

Cholesterol is necessary for your body to make important steroid hormones which are classified into five major groups:

  • Progestogens: Also known as progesterone, which is an important hormone for female reproductive health and pregnancy.
  • Glucocorticoids: Like cortisol, which plays a role in how the body responds to stress and it temporarily lowers inflammation when your body senses a threat.
  • Mineralocorticoids:Aldosterone is a steroid hormone that helps the body regulate blood pressure and plays an important role in heart health.
  • Androgens: Androgens are male sex hormones one is testosterone.
  • Estrogens: Estrogens are one type of female sex hormones.

Cholesterol helps make bile acids that digest and absorb fats

It may sound kinda gross, but your bile plays an important role in your health. Specifically, there are certain bile acids that you need so you can digest and absorb fats well. Cholesterol helps your body produce these acids that it needs.

Bile acids are important for helping your body produce bile flow, which is also important for the absorption of fat-soluble vitamins. Studies also show that bile acids are important for lipid (fat), glucose (sugar) and energy homeostasis.

Cholesterol helps make vitamin D

Cholesterol is also important for vitamin D production. Vitamin D is essential for immune health, bone health, and it plays a role in reducing inflammation. Vitamin D is one of only two vitamins that your body can produce on its own (the other is vitamin K), and you can also get it from other sources like food or supplements.

It's also technically a hormone that regulates how much calcium is in your blood. Studies suggest that vitamin D can help prevent respiratory infections or reduce the severity of them, especially if you have a deficiency.

Why cholesterol matters

Cholesterol circulates in the blood. As the amount of cholesterol in your blood increases, so does the risk to your health. High cholesterol contributes to a higher risk of cardiovascular diseases, such as heart disease and stroke. That&rsquos why it&rsquos important to have your cholesterol tested, so you can know your levels.

The two types of cholesterol are: LDL cholesterol, which is bad, and HDL, which is good. Too much of the bad kind, or not enough of the good kind, increases the risk cholesterol will slowly build up in the inner walls of the arteries that feed the heart and brain.

Cholesterol can join with other substances to form a thick, hard deposit on the inside of the arteries. This can narrow the arteries and make them less flexible &ndash a condition known as atherosclerosis. If a blood clot forms and blocks one of these narrowed arteries, a heart attack or stroke can result.

When it comes to cholesterol, remember: check, change and control. That is:

  • Check your cholesterol levels. It&rsquos key to know your numbers and assess your risk.
  • Change your diet and lifestyle to help improve your levels.
  • Control your cholesterol, with help from your doctor if needed

High cholesterol is one of the major controllable risk factors for coronary heart disease, heart attack and stroke. If you have other risk factors such as smoking, high blood pressure or diabetes, your risk increases even more.

The more risk factors you have and the more severe they are, the higher your overall risk.

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Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.

'Healthy' Sterols May Pose Health Risk

Plant sterols have been touted as an effective way to lower cholesterol and reduce the risk of heart disease. However, a research study in the July JLR has uncovered that these compounds do have their own risks, as they can accumulate in heart valves and lead to stenosis.

Aortic valve stenosis (AS) results from cholesterol accumulation in the valve between the left ventricle and aorta this impedes the flow of blood and puts extra pressure on the heart. About 2% of individuals over 65 (and over 5% of those over 85) have AS, and as the population ages, it is becoming an increasing problem.

Plant sterols can block the absorption of dietary cholesterol into the body, and as such high vegetable diets and/or plant sterol supplements are often used to alleviate high cholesterol. However, although plant sterols themselves are poorly absorbed, they can enter the body, so Satu Helske and colleagues examined whether plant sterols can also accumulate in aortic valves.

They collected blood samples from 82 patients with severe AS and aortic valves from 21 individuals undergoing valve surgery, along with respective controls. They observed that non-cholesterol sterols, including plant sterols, can accumulate in aortic valves, and at levels that directly related to their blood concentration.

These findings suggest that beneficial plant sterols may end up becoming a risk factor for AS, although the researchers will need to conduct more studies, such as whether dietary sterols and sterol supplements produce different effects.

Good cholesterol is a complex measure

While the cholesterol-carrying function of HDL is important, it's not the only way HDL helps your body function. HDL also alters the chemical composition of LDL, preventing it from becoming oxidized, Harvard Medical School reported in 2019. That prevents damage to the arteries and lowers inflammation.

In general, having more HDL is often associated with a lower risk of heart disease. But too much HDL can also cause an inflammatory response in your immune cells, according to a 2016 study in the journal Cell Metabolism. That response can counter its usual anti-inflammatory properties. The upshot is that HDL's function isn't so clear-cut as being "good," rather, its benefit to the body depends on a balance between its positive and negative effects.

To further complicate matters, a separate report from Harvard Medical School suggests that HDL might, in the end, be more of a "bystander" than an agent of good. It might simply be a "marker" of your cholesterol level, rather than having a significant influence on the body.

In fact, the American Heart Association no longer recommends a specific range for HDL and LDL cholesterol — instead, they look at cholesterol as part of your entire heart health.

The takeaway, if you're managing cholesterol, is not to put too much stake into one number. Healthy diet, exercise, and other lifestyle changes can boost your heart health regardless of the precise amount of "good" cholesterol in your body.