Everywhere you turn,you are admonished to pay attention to your cholesterol levels,and to a lesser extent,your triglyceride levels.胆固醇和甘油三酯是脂肪的两种形式，或脂肪，that circulate in your bloodstream.They are both necessary for life itself.
Cholesterol is critical for building and maintaining key parts of your cells,such as your cell membranes,and for making several essential hormones — including the estrogens,progesterone,vitamin D,和类固醇。Triglycerides,它们是由高能脂肪酸组成的链，provide much of the energy needed for your tissues to function.So you can't live without either of these types of lipids.
There are two sources for cholesterol and triglycerides — dietary sources and"endogenous"sources (manufactured within the body).Dietary cholesterol and triglycerides mainly come fromeating meatsanddairy products.这些膳食脂质通过肠道吸收，然后通过血液输送到肝脏，where they are processed.
One of the main jobs of the liver is to make sure all the tissues of your body receive all the cholesterol and triglycerides they need to function.一般来说，for about eight hours after a meal,your liver takes up dietary cholesterol and triglycerides from the bloodstream.During times when dietary lipids are not available,肝脏本身产生胆固醇和甘油三酯。事实上，人体内大约75%的胆固醇是由肝脏制造的。
Your liver then places the cholesterol and triglycerides,除了特殊的蛋白质，into tiny sphere-shaped packages calledlipoproteins,释放到循环中。胆固醇和甘油三酯从脂蛋白中被去除，然后被输送到你身体的细胞中，任何需要它们的地方。
Excess triglycerides — those that are not needed immediately for fuel — are stored in fat cells for later usage.It is important to know that many of the fatty acids stored in our bodies originated as dietary carbs.Because there is a limit to how many carbohydrates we can store in our bodies,any"额外的我们吃的碳水化合物转化为脂肪酸，which are then packaged as triglycerides and stored as fat.（这就解释了为什么即使在低脂饮食中也很容易变得肥胖。）储存的脂肪酸从甘油三酯中分离出来，并在禁食期间作为燃料燃烧。
Good and Bad Cholesterol
You will often hear doctors and dietitians talk about two different"types"of cholesterol —low-density lipoprotein (LDL) cholesterol(so-called"bad"cholesterol),and high-density lipoprotein (HDL) cholesterol (or"好“cholesterol).This way of talking about cholesterol is a convenient shorthand,但严格来说，it is not really correct.
严格来说，as any good chemist will tell you,胆固醇就是胆固醇。一种胆固醇分子和另一种几乎是一样的。So why do doctors talk about good and bad cholesterol??
The answer has to do with lipoproteins.
Lipoproteins.Cholesterol (and triglycerides) are lipids,and therefore do not dissolve in a water medium like blood.为了让脂质在血液中运输而不结块，they need to be packaged into small particles called lipoproteins.Lipoproteins are soluble in blood,允许胆固醇和甘油三酯在血液中轻松移动。
The"behavior"各种脂蛋白中的一种是由其表面出现的特定种类的蛋白质（称为载脂蛋白）决定的。脂蛋白代谢相当复杂，and scientists are still working out all the details.However,大多数医生关心的是两种主要类型的脂蛋白：低密度脂蛋白和高密度脂蛋白。
LDL Cholesterol —"Bad"Cholesterol.In most people,血液中的大部分胆固醇都被包裹在低密度脂蛋白颗粒中。LDL cholesterol is often called"bad"cholesterol.
Elevated levels of LDL cholesterol have been strongly associated with an increased心脏病发作的风险and stroke.It is thought by many experts that when LDL cholesterol levels are too high,the LDL lipoprotein tends to stick to the lining of the blood vessels,which helps to stimulate动脉粥样硬化.So,an elevated LDL cholesterol level is a major risk factor for betway手机平台heart disease and stroke.
While there is no question that elevated LDL cholesterol levels contribute strongly to cardiac risk,近年来，专家们开始质疑降低低密度脂蛋白胆固醇水平本身是否有必要降低风险。In particular,同时降低低密度脂蛋白胆固醇水平statin drugs显著降低心脏风险，用大多数其他药物降低低密度脂蛋白胆固醇水平还没有被明确证明是可行的。这就是为什么一些专家已经开始questioning the cholesterol hypothesis,and why当前治疗胆固醇的指南rely so strongly on the use of statins.
"HDL Cholesterol — Good"Cholesterol.Higher blood levels of HDL cholesterol levels are associated with alower心脏病风险，betway手机平台and conversely,low HDL cholesterol levels are associated with an increased risk.For this reason,HDL cholesterol is commonly called"好“cholesterol.
It appears that the HDL lipoprotein"scours"去除血管壁和多余的胆固醇。所以高密度脂蛋白中的胆固醇是，to a large extent,excess cholesterol that has just been removed from cells and blood vessel walls and is being transported back to the liver for recycling.Thehigher the HDL cholesterol levels,presumably,the more cholesterol is being removed from where it might otherwise cause damage.
In recent years,the notion thatHDL cholesterol is always"好“has come under fire,and indeed,现在看来，真相比简单的要复杂得多。”HDL = good cholesterol."制药公司努力设计提高高密度脂蛋白水平的药物，例如，so far have run into a brick wall.Several drugs that successfully raise HDL levels have failed to improve cardiac outcomes.Results like these are forcing experts to revise their thinking about HDL cholesterol.
Elevated LDL cholesterol levels can be caused by several factors,including heredity conditions such asfamilial hypercholesterolemia.更常见的是胆固醇水平升高与饮食不良有关，obesity,久坐的生活方式，age,吸烟，and gender (pre-menopausal women have lower cholesterol levels than men).
Many clinical studies have shown that having a high triglyceride blood level — a condition calledhypertriglyceridemia-也与心血管风险显著升高有关。While this association is generally accepted by experts,it is not yet agreed that elevated triglyceride levels are a direct cause of atherosclerosis,as LDL cholesterol is thought to be.There is no generally accepted"甘油三酯假设。”"
仍然，there is no question that hypertriglyceridemia is strongly associated with elevated cardiovascular risk.此外，high triglyceride levels are a prominent feature of several other conditions known to increase cardiac risk.包括肥胖，久坐的生活方式，吸烟，hypothyroidism — and especiallymetabolic syndromeand type 2 diabetes.
This latter relationship is particularly important.Theinsulin resistancethat characterizes metabolic syndrome and type 2 diabetes produces an overall metabolic profile that tremendously increases cardiac risk.This unfavorable metabolic profile includes,in addition to hypertriglyceridemia,,CRP水平升高,high LDL cholesterol levels,and low HDL cholesterol levels.(In fact,通常有一个跷跷板”relationship between triglyceride and HDL cholesterol levels — the higher the one,the lower the other.) People with insulin resistance also tend to have hypertension and obesity.Their overall risk of betway手机平台heart disease and stroke is very high.
Given the plethora of risk factors that usually accompany high triglyceride levels,it is understandable that researchers so far have been unable to tease out just how much of the elevated risk is directly caused by the hypertriglyceridemia itself.
Beginning at age 20,建议每五年检测一次胆固醇和甘油三酯。And if your lipid levels are found to be elevated,repeat testing should be done yearly.
Deciding on whether you ought to be treated for high cholesterol or high triglyceride levels,whether that treatment ought to include drug therapy,应该使用哪种药物并不总是一目了然的。仍然，如果你的心血管风险升高，针对你的血脂水平进行正确的治疗可以大大降低你心脏病发作的几率，or even of dying prematurely.所以在治疗胆固醇和甘油三酯方面，把它弄好是很重要的。You can read about current thinking onwhen and how treatment for blood lipids should be chosen.
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低密度脂蛋白胆固醇和甘油三酯水平的升高与心血管疾病的高风险密切相关。尽管对于胆固醇水平和甘油三酯水平的升高本身如何直接导致心脏病仍存在争议，betway手机平台这一点没有争议：如果你的心血管风险升高，你需要减少它；而且，the measures you take to lower your abnormal lipid levels will also lower your cardiac risk.So,let the experts argue about the mechanisms by which cholesterol and triglycerides are associated with betway手机平台heart disease.You should concentrate on taking the steps proven to lower your own,individual risk.