High hdl levels can cut heart attack risk .

高水平hdl可以降低心脏病发作的几率。

Dr. kathiresan said there were many things hdl might indicate .

凯特雷森博士说，hdl有可能指出许多事情。

Animal fats raise ldl cholesterol but do not lower hdl cholesterol .

动物脂肪提高了高密度脂蛋白胆固醇但不会降低低密度脂蛋白胆固醇。

But the hdl story was very different .

但是hdl的情况却完全不同。

Researchers also had a hypothesis to explain how hdl might work .

该研究的研究人员也有一个假设，来解释hdl可能是如何工作的。