By Team ICG® Master Trainer Joan Kent
As many of you know, cholesterol is absolutely vital to our lives and our health. It”™s a waxy, pearl-colored, solid alcohol that”™s produced primarily in the liver, but is so important every cell in the body can make its own.
Cholesterol has widely varied and important functions. It”™s the precursor of all steroids: adrenal hormones, sex hormones, vitamin D and bile acids. It helps to structure cell membranes and modifies their fluidity to compensate for diet-induced changes. It helps to transmit neural impulses. It makes skin “waterproof.” It helps to transport triglycerides. It can function as an antioxidant.
Classifying cholesterol as good or bad hinges on whether it”™s linked with cardiovascular disease or protects from it. A recent article states that high HDL (“good”) cholesterol doesn”™t make up for high LDL (“bad”) cholesterol. This post is about the real cause of high LDL.
Many people think that eating fats raises serum cholesterol. When they try to lower their cholesterol, they reduce dietary fats. But dietary fat doesn”™t necessarily raise serum cholesterol.
Cholesterol synthesis is controlled by an enzyme (HMG-coA-reductase) that”™s triggered by insulin secretion. So foods that raise insulin secretion will increase serum cholesterol. Saturated fat raises cholesterol, but not because it”™s fat. It raises cholesterol because it stimulates insulin secretion. Unsaturated fats don”™t.
Insulin-triggering foods are more likely to increase our cholesterol than healthful fats. It”™s just another way that sugars and processed carbs — and the high insulin secretion they promote — turn out to be bad for us. Good fats help us train well and stay healthy, so the distinction is important.
It works like this. Say you”™ve just treated yourself to a lobster — cholesterol and all — with nothing else. As you digest, the cholesterol is released into your bloodstream. Special receptors, found in each cell, surface and pull cholesterol into the cells to be used in the ways listed above. As cholesterol is pulled into the cell, two things happen: 1) cholesterol production inside the cell stops, and 2) serum cholesterol drops because the cholesterol has been transported into cells.
What if you”™ve had more than lobster? Say you”™ve also consumed some serious insulin triggers: a drink, melted butter, bread and more butter, dessert. The insulin those foods stimulate starts cholesterol production within your cells. As a result, the special receptors don”™t need to pull cholesterol from the bloodstream into the cell because the cell is making its own. Serum cholesterol remains high.
So why is LDL bad and HDL good? Because of their functions.
HDL is a scavenger. It gathers excess LDL and takes it to the liver to be broken down, and to the intestine to be excreted.
LDL transports vital cholesterol through the bloodstream to all of the cells that send up receptors to pull it inside. Along the way, though, cholesterol can stick to arterial linings and create plaque formations. That negative process is known as atherosclerosis. The plaque itself is a combination of LDL and sticky platelets.
If you”™re wondering what makes the platelets sticky, sugar does a spectacular job. And the combination of higher LDL/lower HDL is written up in science journals as the expected result of a low-fat, high-carb diet.
Knowing this is important, so we don”™t eliminate the wrong stuff. A previous post (Controlling the Sugar/Fat Seesaw) listed several benefits of eating healthful (unsaturated) fats, including enhanced endurance. Whether your students ride outdoors or stick to indoor cycling, cutting way back on good fats won”™t help them lower LDL-cholesterol. And it may hurt their endurance. The best thing for them to do is keep the good fats, limit saturated and trans-fats, and cut down on junky carbs.
A few years ago in California, a U.S. national cycling champion taught a workshop on racing and recommended a high-sugar diet: “All the things you think you can”™t eat, ladies!” She listed cookies, cupcakes, pastries, donuts, chocolate milk and more. I would disagree with her approach, which is probably all too common.
But here I”™m simply presenting a way your students can lower “bad” cholesterol without decreasing endurance. Good fats can stay; bad fats and carbs should go. And sugar is ugly.
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