As a recent study indicates, reducing LDL (“bad” cholesterol) can help prevent complications in most people with diabetes. Why is LDL cholesterol a bad thing, and how do you get to a healthy level?
First, what is cholesterol? Discovered in 1769 by analyzing gallstones, cholesterol is a fat-like organic chemical that is an essential part of animal cell membranes. Without it, cells won’t function properly.
Cholesterol is made into bile, which is needed for digesting fats. It is also helps produce the body’s natural steroids, including our sex hormones and the vital stress hormone cortisol. Cholesterol is also central for brain function. You don’t want to go to low. But it can also cause some problems when there’s too much.
You have probably heard that that are two kinds of cholesterol: LDL is the bad stuff and HDL is often called “good cholesterol.” In reality, HDL and LDL cholesterols are essentially the same. The difference is where they go in the body.
LDL stands for “low-density lipoprotein,” and HDL for “high-density lipoprotein.” Lipoproteins are like molecular delivery boats. They take cholesterol around the bloodstream so that cells can use it. Cholesterol needs lipoproteins to get around the bloodstream, a watery environment.
HDL takes cholesterol from the general circulation to the liver where it gets reprocessed. It actually cleans extra cholesterol from blood vessels so they can work better.
LDL goes throughout the bloodstream, and if there’s too much of it, it gets attacked by white blood cells and turned into something called “foam cells.” These cells push cholesterol into the linings of arteries and cause plaque. Plaque narrows arteries and reduces blood flow, putting us at risk for heart attacks and strokes.
Where cholesterol comes from
Generally, then, we want to increase HDL and decrease LDL. We may also want to reduce total cholesterol if we have too much. But how do we do that? We are often told to eat less fat to reduce cholesterol, but this may be misleading.
On the Discover Fit & Health Web site, Dr. Jerry Gordon says that only 15% of our body’s cholesterol comes from food. Eighty-five percent is produced by the cells of our body, in a process called biosynthesis.
Most of this self-made cholesterol is made from carbohydrates. Quite possibly, it’s carbs rather than fats that raise cholesterol.
There are different kinds of fat. Polyunsaturated fats are found mainly in nuts, seeds, fish, and leafy greens. They lower both LDL and HDL.
Monounsaturated fats can be found in vegetable oils, dairy products, nuts, meats, and whole grains. They seem to lower LDL and sometimes raise HDL, so it seems we should surely eat more of them.
Saturated fats come mostly from animal sources. They are fats that are solid at room temperature, like butter or meat fat. They raise both LDL and HDL.
Trans fats are mostly processed unsaturated fats that have hydrogen added to them. They raise LDL and lower HDL, exactly what we don’t want.
However, many studies have shown that lowering fat intake is not effective at lowering cholesterol in our blood. Other studies find that eating a low-carb diet raises HDL much better than a low-fat diet.
How could that be? Most of our cholesterol is made within the body. Insulin is a major signaler for cholesterol production. So eating insulin-stimulating foods (such as refined carbs) may raise cholesterol levels and especially LDL levels.
Why do some bodies produce more HDL and others more LDL? These balances are thought to be mostly genetic and are closely linked with diabetes. A study on people with diabetes found that bad cholesterol levels (called “diabetic dyslipidemia”) are linked to insulin resistance. Many times the bad cholesterol numbers rise before the rise in blood glucose.
What can be done?
It sounds as if we should treat high LDL and high glucose as parts of the same disease.
Writing on Diabetes Self-Management, dietitian Amy Campbell MS, RD, CDE, gave several ways to bring high cholesterol levels down. You can read them all here, but the short course is:
• Taking roughly 15 mg a day of niacin (vitamin B3) — and perhaps as much as 2,000 mg a day, if prescribed — can help. It does have side effects, like severe flushing of the skin in some people.
• Red yeast rice has been shown to lower LDL and may act like a low-dose statin drug. It is available online and at health food stores and Asian food stores. (As always, speak with your doctor before taking this or any other supplement.)
• Exercise can raise HDL quite a bit.
• Stopping smoking has raised HDL in several studies, even when there was weight gain. It had no effect on LDL, though.
According to About.com, cranberry juice has been shown to raise HDL levels. According to articles on AARP and other sites, foods that lower cholesterol and improve heart health include avocado, lentils, edamame (green soybeans), nuts, olive oil, pears, green and black tea, garlic, and onions.
In general, a diet low in refined carbs and high in unsaturated fats seems to work for most people. A low-fat diet does not seem the best way to lower cholesterol, according to several studies, which are summarized on this Paleo diet web site.
Drugs include the statins, which you probably are already taking. They block cholesterol production in the liver.
Other drugs for cholesterol are the fibrates, the best known of which is gemfibrozil ,or Lopid. These work by blocking cholesterol production and seem to especially reduce LDL, possibly even raise HDL. The “bile acid resins” like Questran work by keeping cholesterol in the bile from being reabsorbed into the bloodstream. All of them have significant side effects.
Amy Campbell has some other ideas here. The bottom line is that bad cholesterol seems caused more by insulin resistance than fat consumption. Focus on a diet that lowers your blood glucose, and your cholesterol will probably follow. Has that been your experience?