Journal Name:
Pharmacotherapy
Article Title:
The effect of supplemental dietary fat on plasma cholesterol levels in lovastatin-treated hypercholesterolemic patients.
Date Written:
1995
Volume:
15
Number:
5
Page:
565
Author(s):
McKenney, J.M.; Proctor, J.D.; Wright, J.T. Jr; Kolinski, R.J.; Elswick, R.K. Jr; Coaker, J.S.
Article:
The National Cholesterol Education Program (NCEP) guidelines for the evaluation and treatment of high blood cholesterol in adults recommends a step 1 diet restricting fat and cholesterol initially, and for patients requiring additional cholesterol lowering, a step 2 diet. Drug therapy may also be considered. This approach was established to encourage cholesterol control with diet alone. Little is known about the interaction of diet and drug therapy. When used alone, a step 1 diet will lower total cholesterol 5-7% and a step 2 diet will lower it an additional 3-7%, for an overall 10% average reduction. When diet is combined with drug therapy, a step 2 diet contributes about 5% to the reduction in total cholesterol levels in free-living patients to as much as 15% in patients in a metabolic ward. The objective of this research was to document the effect on blood cholesterol levels of adding saturated and unsaturated fatty acids to the diet of patients administered a low-fat diet and lovastatin therapy.
A randomized, crossover design, with three periods in the first study and four in the second study, each lasting 6 weeks was conducted. The first study evaluated adults with total cholesterol levels between 200 and 280 mg/dl (5.172 and 7.241 mmol/L). The second study included adults with low-density lipoprotein (LDL) cholesterol levels above 160 mg/dl (4.138 mmol/L). Fat supplements with either coconut or canola oil were provided in oatmeal-raisin cookies.
The results showed that following the validation study, patients' mean pre-randomization total cholesterol level of 222 mg/dl was significantly educed to 213 mg/dl with canola oil and increased to 233 mg/dl with coconut oil cookies. In the second study the mean prerandomization total cholesterol level of 214 mg/dl was significantly decreased to 199 mg/dl with canola oil and to 208 mg/dl with coconut oil cookies. The LDL cholesterol levels changed in a similar fashion in both studies.
The addition of unsaturated fatty acids (canola oil) to the diet lowered blood cholesterol levels slightly more in patients in the lovastatin-cookie study (7.1 %) than in those in the validation study (4.1%). Unsaturated fatty acids may augment the cholesterol-lowering effect of lovastatin. Monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) enhances the clearance of LDL particles, which suggests an increase in LDL receptor activity.
The interpretation of the results of the two studies is limited by several factors. The study populations were different, and thus comparisons between them may not be valid. The addition of supplemental fat calories to patients' total caloric intake led to an average weight gain of almost 5 pounds in both groups, and this may have affected the results.
Changes in total and LDL cholesterol levels in the validation study were expected based on established effects of saturated and unsaturated fatty acids. The changes in these levels in lovastatin-cookie study were not expected and may have occurred because lovastatin reversed the effect of saturated fats and enhanced the effect of unsaturated fats. Alternatively, enhanced bioavailability of lovastatin when administered with a high-fat diet may have occured. These results must be confirmed in other controlled clinical trials before they can be applied to clinical practice.
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