While cholesterol is often considered a marker of poor cardiovascular health and a risk factor for heart disease and stroke, in actuality, it's an essential biomolecule that performs many functions in the body. The cells need cholesterol so much, in fact, that they don't rely on nutritional sources of the molecule -- they can synthesize it from dietary fat. There are many benefits to appropriate levels of cholesterol in cells.
Vitamin D Synthesis
Vitamin D is a micronutrient, meaning that the body needs vitamin D in the diet in small amounts. Unlike the macronutrients -- protein, carbohydrate and fat -- the micronutrients don't provide energy. Instead, cells use vitamins to help run various reactions. Vitamin D, for instance, assists in uptake of dietary calcium, which is important not only to the health of the skeletal system but also to heart and muscle function. According to Dr. Lauralee Sherwood in her book "Human Physiology," humans can obtain vitamin D from food, but they can also make it in the cells. The synthesis of vitamin D takes place when cholesterol in the skin reacts with sunlight, producing the active form of the vitamin.
Hormone Synthesis
Cells also use cholesterol as the starting material for the synthesis of a variety of hormones. Unlike peptide hormones, including insulin, which are made of protein, steroid hormones are slower-functioning hormones that have chemical structures similar to that of cholesterol, since they're made from cholesterol. According to Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry," steroid hormones include testosterone, estrogen, progesterone and aldosterone -- all of which are essential to normal human body function. Without adequate cholesterol, cells can't produce hormones.
Membrane Maintenance
Every body cell is surrounded by a fluid-like membrane that is essential to cellular function in many ways. First, the cell membrane helps protect the cell from infection by pathogens. Second, the cell membrane is important to communication with other cells and allows cells to send and receive signals. Finally, normally operating membranes control flow of various chemicals into and out of cells. For membranes to work, note Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry," they must be appropriately fluid, but not overly fluid. Cholesterol helps increase the stability of membranes and prevents them from becoming overly fluid and dissolving.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
