14 previously untreated patients with hyperlipoproteinemia type IIa according to 
Fredrickson underwent a controlled clinical trial. The study was designed to 
clarify the effects of clofibrate on the bloodlipids. All patients were willing 
to cooperate. After leaving their usual dietary habits all of them were given 
for seven to ten days a "prudent" diet. This diet was rich in vitamins; it had a 
low caloric-content. 20% of the calories consisted of proteins, 35% of 
carbohydrates (sweets were omitted) and about 45% of fats with a PS-factor of 
about 2.2. After the initial dietary treatment all patients were given twice 
daily for 14 days 500 mg clofibrate. During the use of the "prudent" diet the 
serum-cholesterol-levels decreased in average with 14.8%. Compared to the values 
at the beginning of the trial the difference was statistically highly 
significant. The average-values of triglycerides, phosphatides and the relative 
percentage of HDL, LDL and VLDL remained unchanged. After the patients received 
clofibrate there was an additional decrease of the serum-cholesterol-values of 
14.8%. The total decrease of the cholesterol-levels compared to the initial 
values amounted to 27.4%. Furthermore, there was a reduction of the phosphatids 
in the serum of 14.1% compared to the initial value and of 9.9% compared to the 
value after dietary treatment alone. Under the combined effects of a "prudent" 
diet with clofibrate the HDL increased significantly. It can be assumed that 
clofibrate reduces the serum-cholesterol-levels in cases of hyperlipoproteinemia 
by decreasing the LDL-fraction, which is rich in cholesterol, and by increasing 
the HDL-fraction.