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Can Cholesterol Levels Go Too Low?

Moderation seems best for so many things in life. And apparently this may also be true for a person's cholesterol levels. In a large study researchers found that having low levels of LDL cholesterol (below 70 mg/dL) significantly increased the risk of hemorrhagic stroke (intracerebral hemorrhage).Typically, lowering LDL (low-density lipoprotein) cholesterol is recommended as a way to reduce the risk of a heart attack or ischemic stroke, but several studies now confirm this very low LDL cholesterol - hemorrhagic stroke association.

The study was led by Pennsylvania State University researcher Xiang Gao, but conducted over a 9 year period in an industrial area in northern China. The 96,043 participants had their LDL cholesterol levels measured 4 times over that period. The researchers didn't find any increased risk of hemorrhagic stroke when LDL levels were above 70 mg/dL.

From Medical Xpress: Cholesterol that is too low may boost risk for hemorrhagic stroke

Current guidelines recommend lowering cholesterol for heart disease risk reduction. New findings indicate that if cholesterol dips too low, it may boost the risk of hemorrhagic stroke, according to researchers. 

Over a period of nine years, a Penn State-led study examined the relationship between low-density lipoprotein cholesterol—LDL, commonly known as "bad" cholesterol—and hemorrhagic stroke. This type of stroke occurs when a blood vessel bursts in the brain. The researchers found that participants with LDL cholesterol levels below 70 mg/dL had a higher risk of hemorrhagic stroke

Xiang Gao, associate professor of nutritional sciences and director of the Nutritional Epidemiology Lab at Penn State, said the results—published today (date) in Neurology—may help refine and personalize recommendations for ideal target cholesterol levels.

"As is true with many things in nutrition, moderation and balance is key when deciding the optimal target level of LDL cholesterol," Gao said. "You can't go to either extreme—too high or too low. And if you're at a high risk for hemorrhagic stroke due to family history or risk factors like high blood pressure and heavy alcohol drinking, you may want to be extra careful about LDL cholesterol levels."

According to the researchers, low LDL cholesterol is recommended as a way to reduce the risk of a heart attack or ischemic stroke—the latter when a blood vessel in the brain becomes blocked by a clot. But previous research has suggested a link between very low LDL cholesterol levels and hemorrhagic stroke.

Chaoran Ma, a nutritional sciences graduate student at Penn State, said that while previous studies suggested this connection, there was a need for additional validation in a separate cohort. ... The study included 96,043 participants with no history of stroke, heart attack or cancer when the study began. LDL cholesterol levels were measured when the study began and yearly thereafter for nine years. Reported incidents of hemorrhagic stroke were confirmed by medical records.

The researchers found that participants who had LDL cholesterol levels between 70 and 99 mg/dL had a similar risk of hemorrhagic stroke. But, when LDL cholesterol levels dipped below 70 mg/dL, the risk of hemorrhagic stroke increased significantly. For example, the risk increased by 169 percent for participants with LDL levels less than 50mg/dL relative to those with LDL levels between 70 and 99 mg/dL. These findings were consistent after controlling for age, sex, blood pressure and medication.

"Traditionally, an LDL cholesterol level of more than 100 mg/dL had been considered as optimal for the general population and lower in individuals at elevated risk of heart disease," Gao said. "We observed that the risk of hemorrhagic stroke increased in individuals with LDL cholesterol levels below 70 mg/dL. This observation, if confirmed, has important implications for treatment targets."

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