Too Much of a Good Thing
Your body needs cholesterol to function, but it can also make serious trouble
Cholesterol: Just the thought of it can stir up anxieties about the foods you eat, the medications you take, and your health in general. But what is cholesterol? How is it harmful? And how can you keep it in check? Below you'll find some answers about this tiny molecule with a big reputation.
Cholesterol is a greasy, fat-like substance crucial to the workings of the human body. Although it is available in food, cholesterol is so important that the body doesn't rely on the diet to provide all of it. In fact, 75 percent of the cholesterol you need is generated by the body itself.
One of cholesterol's functions is architectural, inserting itself into the lipid-based membranes that surround cells and giving them just the right amount of flexibility. Additionally, cholesterol is the major building block for hormones like estrogen and testosterone. To do these jobs, cholesterol must constantly be shuttled through the body in the circulatory system.
Since water and fats don't mix, cholesterol gets chaperoned through the bloodstream by tiny soluble particles called lipoproteins. You may be familiar with two of these lipoproteins: low-density lipoprotein (LDL) and high-density lipoprotein (HDL). The cholesterol being carried by these lipoproteins takes their first names, as in "LDL cholesterol" and "HDL cholesterol." LDL cholesterol and HDL cholesterol are hugely different in how they behave and what they mean for a person's health, which is why LDL cholesterol is often called "bad" and HDL cholesterol "good." The amount of cholesterol found in LDL or HDL particles is a big part of the risk equation for heart disease and stroke.
Dyslipidemia, an imbalance of blood lipids (HDL cholesterol, LDL cholesterol, triglycerides, and fatty acids), is common among people with diabetes and is a serious health risk. Cholesterol and other lipids can end up lining arteries in waxy deposits called plaques. As plaque build-up escalates--a condition called atherosclerosis--blood can have a difficult time moving through the increasingly narrow passageways. Atherosclerosis can occur in any artery in the body, increasing risk of heart attack and stroke.
Intensive research on dyslipidemia has identified how much of each blood lipid is healthy and how much is too much for different genders (see "Know Your Numbers," below). There are a few kinds of tests that doctors can run to check LDL cholesterol and HDL cholesterol levels. When a person's cholesterol gets out of whack--high LDL and low HDL cholesterol--a doctor can turn to an arsenal of lifestyle advice and medications to bring them back under control.
New United States government guidelines advise that adults engage in 2.5 hours of physical activity a week--preferably 30 minutes a day, most days. Exercise has been shown to lower LDL cholesterol and raise HDL cholesterol. Scientists aren't exactly sure how this works, but they've done numerous studies to establish the heart-healthy relationship between sweat and cholesterol.
Your body is always going to be making some of its own, so there's no point in adding to the problem with cholesterol-rich foods. Even if you stopped eating cholesterol entirely, your body has the ability to produce enough cholesterol on its own to compensate. Eating foods low in cholesterol is a good start, but limiting your intake of saturated and trans fats is also important because their consumption boosts blood LDL cholesterol levels. The American Diabetes Association (ADA) recommends keeping saturated fat to less than 7 percent of daily caloric intake--that's just 15 grams a day for most people. Trans fats are even nastier than saturated fats, which is why you should avoid them as much as possible. When reading a food label, remember that "hydrogenated oil" and "partially hydrogenated oil" are code for trans fat--even if the amount of trans fat is listed as 0. And as for cholesterol itself, if you have too-high LDL, it's a good idea to keep intake to less than 200 mg per day.
But what fun would an entirely fat-free diet be? When a fat craving strikes, stick to heart-healthy monounsaturated or polyunsaturated fats; they actually tend to lower LDL cholesterol levels. Some healthy fat foods are avocado, olive oil, and nuts--but don't (ahem) go nuts; these treats are calorie dense. And don't forget the omega-3 fatty acids found in fish and some types of oil; they may not lower cholesterol, but they can lower triglycerides.
Finally: If you smoke, it's time to stop. Smoking can lower "good" HDL cholesterol and up the tendency for blood to clot, which is bad news for your heart.
- Statins are the most commonly prescribed cholesterol-lowering medication and typically drop LDL cholesterol levels by between 20 and 60 percent. They may also raise HDL cholesterol and lower triglyceride levels, though much less dramatically. Clinical trials have proven that statin use lowers the risk of heart attack and cardiovascular death for people with diabetes. Statins reduce cholesterol by blocking an enzyme--called HMG-CoA reductase--that normally is involved with cholesterol production in the body. Not only do statins disrupt the making of cholesterol, but they also help the liver remove LDL cholesterol from the blood. There are several different types of statins currently on the market--ask your doctor which is right for you. Usually, statins are taken once a day and are not associated with major side effects.
- Fibrates, can raise healthy HDL cholesterol (10 to 15 percent) and lower triglycerides (20 to 50 percent). Studies have shown that in people who struggle with low HDL and high triglycerides, fibrates can reduce heart attack risk. Generally, fibrates are well tolerated.
- Bile Acid Binders, as the name implies, grab onto bile acids--along with the cholesterol stuck to them--and usher them out of the body via the stool. Often a binder will be combined with a statin for a cholesterol-lowering one-two punch that typically reduces LDL cholesterol by more than 40 percent. A bile acid is a chemical that makes cholesterol soluble, allowing cholesterol to be reabsorbed by the body instead of exiting the body as waste. Bile acid binders interfere with this process, which is good for people with high levels of LDL cholesterol. This medicine comes as a tablet or a powder, taken once or twice a day. To avoid gastrointestinal distress both must be accompanied by lots of fluids.
- Niacin--a B vitamin--can positively affect blood levels of triglycerides (down 20 to 50 percent), HDL cholesterol (up 15 to 35 percent), and LDL cholesterol (down 10 to 20 percent). However, it is important that niacin therapy be monitored by a doctor, who can watch for any harmful side effects. One common side effect of taking this supplement is hot flashes. A caveat for people with diabetes is that niacin sometimes modestly raises blood glucose levels, so your doctor may need to monitor this.
- Ezetimibe lowers LDL cholesterol levels by interfering with the absorption of cholesterol in the intestines. It is taken daily; side effects can include diarrhea, joint pain, or fatigue.
While side effects are unusual with all of these medications, they can be life threatening. Ask your doctor what symptoms you should watch out for with your particular treatment regimen.
If you've got a cholesterol problem, consult your physician, and make a plan about how to get it under control. With some information and a good attitude--you have the tools to keep healthy.
Know Your Numbers
The American Diabetes Association recommends these lipid levels for people who have diabetes.
- LDL cholesterol--less than 100 mg/dl (if you have cardiovascular disease or an additional risk factor: less than 70 mg/dl)
- HDL cholesterol--Women: more than 50 mg/dl; Men: more than 40 mg/dl
- Triglycerides--less than 150 mg/dl
Source: Diabetes Care, Supplement 1, Clinical Practice Recommendations, January 2008