Cutting cholesterol right back to the levels we were born with reduces the risk of heart attacks and strokes by a third, a study in England has shown.
Scientists made the discovery after analysing data from more than 5,000 people taking part in trials of a super-powerful cholesterol-lowering therapy.
The results showed that cutting blood cholesterol to less than 50 milligrams per decilitre (mg/dL) - the level of a newborn baby - had a major impact on the health of individuals already suffering from heart disease or at high risk of the condition.
Over a period of up to two years, the treatment lowered the risk of heart attack, stroke or fatal heart disease by about a third.
For every 39mg/dL reduction in the harmful form of cholesterol, low density lipoprotein (LDL), the risk fell by 24%.
Lead researcher Professor Kausik Ray, from the School of Public Health at Imperial College London, said: "Experts have been uncertain whether very low cholesterol levels are harmful, or beneficial. This study suggests not only are they safe, but they also reduce risk of heart disease, heart attack and stroke."
All the patients, with an average age of 60, had previously been diagnosed with high cholesterol, and many were slightly overweight.
They had an average cholesterol reading of 125 mg/dL and most were taking cholesterol-lowering statin drugs. Just over half were also undergoing treatment with a new injected drug, alirocumab, to reduce their cholesterol levels further.
Some patients find their cholesterol levels cannot be kept under control by statins alone, possibly because they carry a faulty gene.
Combining statins with alirocumab caused cholesterol levels to drop to below 50mg/dL, a reduction that would be impossible without medication.
Prof Ray added: "This study not only confirms that LDL can trigger heart problems, but also suggests reducing it in adults to very low levels - to those of a newborn baby - is both safe and beneficial."
Longer term data is now needed to see if the beneficial effects continue, he said.
The study, published in the journal Circulation, was funded by the international drug company Sanofi and US biotech firm Regeneron Pharmaceuticals.