Ashley Rivers, MD

As we all know cholesterol is a fat and does not dissolve in water. A blood test for cholesterol samples the water half of the blood, the serum. Clearly a conundrum — we test the water half of the blood for a substance that cannot dissolve in water.

This puzzle was solved in 1985 by two scientists in Texas who received the Nobel Prize for their work. Their discovery was that animal livers, including humans, solve this problem by wrapping cholesterol in a protective shell made of cell membrane to make an “LDL particle.” The particles can dissolve in the serum whereas the cholesterol molecules inside the particle cannot.