Shocking results from a new study published in the journal Nature Communications reveals how high levels of HDL cholesterol can cause partial or complete blindness.
This is especially alarming since you’ve been given advice for decades to raise it and millions of people are taking prescription drugs aimed at boosting this type of “good” cholesterol.
The researchers were examining the consequences of high and low body mass index, waist to hip ratio, cholesterol, triglycerides (circulating fat), and blood pressure when they made this discovery.
They went about it in a particularly clever way by using genetic information to exclude the interference of environmental factors.
Think about it: if you want to find out whether high cholesterol causes cancer, you can analyze the information of thousands of people, find those with high cholesterol, and check whether they are more likely to have cancer than those with low cholesterol.
But there is a problem with this kind of study. People with high cholesterol may not only have high levels of cholesterol in common, but also particular eating habits and lack of exercise.
In this case, how can researchers tell whether the cancer is caused by high cholesterol or by poor diet or lack of exercise?
To get around this problem, scientists often use the genetic variant previously established to cause high cholesterol, rather than high cholesterol itself, to establish a link with cancer rates. Presumably, since people are born with a genetic variant, this excludes dieting, exercise, and other environmental factors from the equation.
That is what the researchers in the Nature Communications study did.
They took the genetic variants related to cholesterol, blood pressure, and the other conditions listed above from participants in two studies, overall, just over 160,000 people.
They then listed the diseases from which each of these people suffered, and compared the two lists with each other.
There were many unsurprising findings, such as that those prone to obesity were more likely to have type II diabetes and arthritis, and that those with high cholesterol were at risk of coronary artery disease.
But the interesting discovery was that, together with protecting against diabetes, hypertension, and cardiovascular disease, HDL cholesterol (commonly called good cholesterol) increases our risk of developing age-related macular degeneration.
Macular degeneration is a more common cause of blindness than cataracts and glaucoma.
It happens when the cells that make up the middle part of your retina, called your macula, deteriorate and die. This causes the central part of your visual field to become blurry and later dark.
If these studies are right, it means that you should never try to increase your HDL levels artificially using medications.
The key is to create a balance between good (HDL) and bad (LDL) cholesterol, using simple lifestyle changes.