My answer to What happens if you don't get enough dietary cholesterol?
Answer by Connie b. Dellobuono:
MS, mental health issues, digestive health issues and bone health issues may arise as a result of lack of dietary cholesterol.
From Wiki:
Cholesterol & phospholipids, both electrical insulators, in multiple layers, can facilitate speed of transmission of electrical impulses along nerve tissue. For many neuron fibers, a myelin sheath, rich in cholesterol, since it is derived from compacted layers of Schwann cell membrane, provides insulation for more efficient conduction of impulses. The liver excretes cholesterol into biliary fluids, which is then stored in the gallbladder. Bile contains bile salts, which solubilize fats in the digestive tract and aid in the intestinal absorption of fat molecules as well as the fat-soluble vitamins, A, D, E, and K. It is required to build and maintain membranes; and modulates membrane fluidity over the range of physiological temperatures.
Since cholesterol is essential for all animal life, each cell synthesizes it through a complex 37 step process beginning with the mevalonate pathway and ending with a 19 step conversion of lanosterol to cholesterol.
A human male weighing 68 kg (150 lb) normally synthesises about 1 g (1,000 mg) per day, and his body contains about 35 g, mostly contained within the cell membranes. Typical daily cholesterol dietary intake for a man in the United States is 307 mg (above the upper limit recommended by the Dietary Guidelines Advisory Committee
Most ingested cholesterol is esterified, and esterified cholesterol is poorly absorbed. The body also compensates for any absorption of additional cholesterol by reducing cholesterol synthesis.
For these reasons, cholesterol in food, seven to ten hours after ingestion, has little, if any effect on concentrations of cholesterol in the blood. However, during the first seven hours after ingestion of cholesterol, as absorbed fats are being distributed around the body within extracellular water by the various lipoproteins (which transport all fats in the water outside cells), the concentrations increase.
It is also important to recognize, however, that the concentrations measured in the blood plasma of samples vary with the measurement methods used. Traditional, simpler, cheaper methods do not reflect (a) in which lipoproteins the various fat molecules are being transported or (b) which cells are ingesting, burning or exporting the fats molecules being measured as totals from samples of blood plasma.
Cholesterol is recycled in the body. The liver excretes it in a non-esterified form (via bile) into the digestive tract. Typically, about 50% of the excreted cholesterol is reabsorbed by the small bowel back into the bloodstream.