All patients will undergo drug therapy as required to treat their clinical symptoms including the use of other classes of cholesterol-lowering drugs like statins (that will not interfere with intestinal cholesterol levels). One group of patients will be those who in addition to there existing drug therapy are prescribed ezetimibe to lower circulating cholesterol concentrations. A second group of patients will be those who are not prescribed ezetimibe as part of their normal course of therapy. Blood samples will be taken from all patients at the study baseline. All patients will be fasted for 12 hours prior to the blood sample being taken. After 6 weeks a second blood sample will be taken. This will determine if the drug intervention (ezetimibe) influenced the circulating omega-3 fatty acid concentration.