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Genes May Override Exercise in Cholesterol War

Regardless of Exercise Level, Genes May Determine Effects of High-Fat Diet

WebMD Health News

July 13, 2005 -- For some people, no matter how much time they spend at the gym or on the couch, it may have little effect on their cholesterol levels.

A new study of identical twins suggests that genes play a major role on how sensitive our bodies are to fat in the diet, regardless of physical activity levels.

Researchers say the findings may help explain why some sedentary people can eat a high-fat diet without suffering the artery-clogging consequences while others who exercise regularly still suffer from high cholesterol levels.

The risk of heart disease increases with elevated low-density lipoprotein (LDL) cholesterol levels, and decreases with rising high-density lipoprotein (HDL) levels.

Eating a healthy, low-fat diet and regular exercise can help the vast majority of people maintain healthy cholesterol levels. But researchers say their results show that some people may be born with genes that make them naturally more sensitive or resistant to dietary cholesterol, whether they're a couch potato or a marathon runner.

Genes May Determine Cholesterol Levels

In the study, researchers compared the effects of switching between a high-fat diet and a low-fat diet in a group of 28 male twin pairs in which one twin was an avid runner and the other was sedentary.

The running twin logged about 40 kilometers more per week than his brother, if the brother exercised at all.

Each twin followed a high-fat diet in which 40% of the calories came from fat for six weeks and then switched to a low-fat diet with 20% fat for another six weeks. Their cholesterol levels were measured after each six-week period.

The results showed that the twins' cholesterol levels responded very similarly to the different diets, despite the big difference in their exercise levels.

For example, if one sedentary twin experienced a rise in total or LDL "bad" cholesterol levels on the high-fat diet, so did his "running" brother. Similarly, if one active twin saw his LDL cholesterol decrease on the low-fat diet, so did the couch-potato twin.

But some twins seemed to be born with genes that made them insensitive to dietary fat and experienced little change in their cholesterol levels on either diet.

"Our results suggest there are genes that strongly influence the LDL-cholesterol response to diet, even in the presence of large differences in physical activity," write researcher Paul Williams, of Lawrence Berkeley National Laboratory, and colleagues in the July issue of the American Journal of Clinical Nutrition.

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Your total cholesterol level is in the Desirable range, but your level of "bad" LDL cholesterol is Very High. This may mean that your level of high-density lipoprotein (HDL), or "good" cholesterol, is too low. It is best to have a high level of "good" HDL and a low level of "bad" LDL because the HDL helps keep your LDL level in check. Ask your doctor for your HDL level. If your HDL is low, increasing your physical activity can increase it, which may help reduce your LDL level.

Your total cholesterol level is Borderline High, but fortunately your level of "bad" LDL cholesterol is optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have other non-measured increases in LDL-like particles that can increase heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol level is Borderline High, but fortunately your level of "bad" LDL cholesterol is near optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have other non-measured increases in LDL-like particles that can increase heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol level is Borderline High. Your level of "bad" LDL cholesterol is Borderline High, too. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol level is Borderline High. Your level of "bad" LDL cholesterol is High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol level is Borderline High. But your level of "bad" LDL cholesterol is Very High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol is High, but your level of "bad" LDL cholesterol is optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have elevated secondary lipids, such as non-HDL particles that increase the risk of heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol is High, but your level of "bad" LDL cholesterol is near optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have elevated secondary lipids, such as non-HDL particles that increase the risk of heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol level is High. Your level of "bad" LDL cholesterol is Borderline High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol level is High. Your level of "bad" LDL cholesterol is High, too. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels! If you are struggling to bring down your total cholesterol and LDL cholesterol levels, your doctor may prescribe medication, such as statins. Following medication, dietary, and exercise instructions should result in improvements.

Your total cholesterol level is High, and your level of "bad" LDL cholesterol is Very High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels! If you are struggling to bring down your total cholesterol and LDL cholesterol levels, your doctor may prescribe statins or other cholesterol-lowering medications.

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