On Friday morning, April 16, 2004, Mohamed Hadibèche, then a 44-year-old truck driver, felt a mild pain in his chest. It was gone within minutes. The following morning, the pain returned – again, subsiding soon after. So when the pain returned the next afternoon, he assumed he could ignore it. But this time it rapidly grew more intense. “I felt I had a stake deep in my chest,” recalls Mohamed. His wife, Houria, insisted on getting him to hospital.
Mohamed couldn’t have known it that Sunday, but inside the walls of the arteries leading to his heart, cholesterol had been building up. Over time, this cholesterol had hardened into a substance called plaque, creating a condition called atherosclerosis. These plaques narrowed the space through which his blood flowed.
When plaques rupture, as they sometimes do, blood clots can form, further interfering with the flow of blood. This appears to be what happened to Mohamed. Blocked by hard, calcified cholesterol and clots, oxygen-rich blood could no longer reach his heart. And Mohamed Hadibèche suffered a heart attack.
What is cholesterol, and why do we have it?
Cholesterol is a fat-like substance called a lipid that’s primarily produced by the liver. We couldn’t live without it. “You need it for hormones, DNA, and cell membranes,” says Dr Ian Graham, professor of cardiovascular medicine at Trinity College in Dublin, Ireland. If not for cholesterol, your brain couldn’t function.
But cholesterol doesn’t swim through your blood vessels all by itself. When your doctor tells you about your cholesterol levels, she’s actually talking about the levels of several different types of particles that include cholesterol as just one component. These tiny particles are called lipoproteins, because their exteriors are made up of proteins, while the interior contains the lipid cholesterol and a second lipid called triglyceride. (Triglycerides make up most of the fat in your body.)
Your cholesterol test only measures the first two major lipoproteins. Low Density Lipoprotein (LDL), named for its lower concentration of cholesterol, is commonly labelled “bad” cholesterol because it contributes to plaque. High Density Lipoprotein (HDL) is the so-called “good” cholesterol because it is thought to help remove LDL cholesterol from the arteries. The third major lipoprotein is Very Low Density Lipoprotein (VLDL), a larger particle with a high concentration of triglycerides.
These lipoprotein particles circulate through your bloodstream, dropping off molecules of cholesterol and other substances wherever they are required – and sometimes where they’re not. Because, despite how important cholesterol is to your body’s functioning, you can have too much of this good thing. “We have four times more than we need,” says Professor Graham. “Nobody quite knows why.”
But when that excess goes where it’s least welcome – stuck to the walls of your arteries, as happened to Mohamed – it increases the risk of heart problems. If the arteries leading to the brain are involved, it can increase the risk of stroke.
Not all heart problems are related to high cholesterol, but the World Health Organization estimates that cholesterol is responsible for a third of coronary heart disease cases. That’s significant, because cardiovascular disease is the number-one cause of death globally, accounting for more than 17.5 million deaths a year. Meanwhile, high triglycerides, fats that rise when “good” cholesterol levels fall, can double the risk of stroke, says a large 2012 study.