Cholesterol has a bad reputation in nutritional chemistry, only part of which it actually deserves. In reality, the cholesterol molecule is critical to maintaining life and health -- you couldn't survive without cholesterol in your body. You can obtain cholesterol in two different ways: You can consume it through certain foods, or you can produce it from raw materials already in your body.
The Cholesterol Molecule
While too much cholesterol in the bloodstream can build up in your arteries and lead to heart disease and an increased risk of stroke, you need a certain amount of cholesterol in the body to maintain normal function. For instance, cholesterol helps regulate the stiffness of your cell membranes, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." Furthermore, you make steroid hormones, which help cells communicate with one another, and vitamin D from cholesterol.
Cholesterol Synthesis
Because cholesterol is so important to your health, your body can obtain it in one of two ways -- you can either get it from the food you eat, or you can make it. One of the interesting aspects of human biochemistry is that your cells can make a great variety of molecules from relatively few simple materials. One of the most common materials for making different molecules is called acetyl-CoA. You obtain acetyl-CoA by burning carbohydrates, proteins and fats, and you can use acetyl-CoA to make cholesterol.
Pathway
The pathway by which you make cholesterol from acetyl-CoA is very long and complicated, involving many different enzymes. The reason it's critical that this pathway involve enzymes is that they help regulate cholesterol synthesis. Enzymes help chemical reactions take place faster than they otherwise would, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry," and your cells can turn them on and off as needed. In general, if you eat extra cholesterol, your cells will turn off the enzymes of cholesterol synthesis. If you eat less cholesterol, your cells will turn on the enzymes of cholesterol synthesis.
Other Considerations
Most of the cholesterol your body makes is made in the liver, though other organs can also make cholesterol, note Campbell and Farrell. Statin drugs are pharmaceuticals that help reduce your cholesterol levels if your blood cholesterol is too high; these drugs target the first step of cholesterol synthesis by blocking the enzyme that converts acetyl-CoA into the first cholesterol precursor molecule.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
