Scientists have discovered how to block cholesterol absorption in the intestine.
Researchers have found how a cholesterol lowering drug works
They have identified a key protein which seems to control the passage of cholesterol into the bloodstream.
Not only does this help to explain how anti-cholesterol drugs work, it could also lead to more effective drugs being developed.
The research, published in Science, was conducted by a team at the Schering-Plough Research Institute.
Dr Michael Graziano and colleagues found a protein encoded in the genes of intestinal cells, called NPC1L1, helps the intestine to absorb cholesterol into the bloodstream.
They experimented on genetically modified mice that lacked the protein and compared them to a group of normal mice.
The genetically modified group absorbed 70% less cholesterol than the control group.
However when given ezetimibe, a cholesterol lowering drug, the absorption rate in the control group was lowered to a similar extent of the modified mice.
This suggests that the drug works by actually blocking the protein.
Previously, scientists have been unable to explain why some cholesterol-lowering drugs have actually worked in patients.
The majority of studies have looked at cholesterol absorption in the liver, where cholesterol is produced, rather than in the intestine.
The scientists are now looking into other proteins that are involved with cholesterol absorption.
Belinda Linden, Head of Medical Information at the British Heart Foundation, welcomed the research but said statins are still the first drug of choice.
High cholesterol levels can lead to heart disease
"This research is very welcome as it has helped us to further understand ezetimibe's beneficial effect," she told BBC News Online.
"Statins, however... are safe, effective and may offer added protection to the artery wall,"
She added that people can also lower cholesterol levels by small lifestyle changes.
"Not smoking, eating a low fat diet which contains oily fish and is high in fruit and vegetables, and by doing 30 minutes of moderate exercise five times per werk can help keep the heart healthy."
High cholesterol levels can cause fattening of the arteries, a condition known as atherosclerosis, which can lead to heart disease.
Around 46% heart attacks in people under 75 are caused by high cholesterol levels.
A fatty diet is the main contributor to high blood cholesterol.