The causes of death are different, however. Those with high cholesterol are killed by heart disease. It's not clear why cholesterol levels below 160 are connected to this diverse group of deadly diseases. Researchers have proposed that the low cholesterol itself isn't the cause but rather the effect of the disorders. Alcoholism, for example, is associated with very low cholesterol, perhaps due to inadequate nutrition.
Alcoholism also increases the risk of liver and digestive disease, certain cancers, and suicide.
Adding to the uncertainty, the minimum cholesterol level requirement for normally healthy people isn't known. We need some cholesterol. It is an important part of our cells and is involved in the formation of hormones. Since these studies were published, there has been some question concerning the wisdom of low cholesterol diets and particularly of cholesterol lowering medications. But most experts still believe they are necessary since the relationship between elevated cholesterol and heart disease is definite and strong.