Effects of a Long Term Dietary Portfolio and of Sequential Removal of Food Components From the Diet

We have shown in 1-month metabolic studies that a dietary portfolio, consisting of soy products, viscous fibers, almonds and plant sterols in the form of margarine, can lower cholesterol to the same extent as first generation statins (cholesterol-lowering drugs). However, the long-term effectiveness of the dietary portfolio is not known. Furthermore, it is not known to what extent each of the food components contribute to the cholesterol reductions observed. We wish to therefore evaluate the long term effects of the dietary portfolio as well as the effects of removing single food components from the dietary portfolio on cholesterol reduction and other cardiovascular risk factors. We believe the removal of single food components will result in a reduction of the cholesterol-lowering effect to a similar extent as predicted with the cholesterol reductions observed when the food component is consumed alone.

Method:

66 subjects will be recruited for a 6-month to 5 year long-term dietary portfolio study with the option for continuation (re-consenting) at the end of 6, 12 or 24 months. The active dietary components consist of viscous fibers (including oat bran), soy products (including soy milk), almonds and plant sterols (sterol-enriched margarine). Lipids, blood pressure, body weight, and routine biochemical and hematology analyses will be performed over the 5 year period, with lipids and blood pressure measured at 2 monthly intervals. 40-50 subjects on the long term dietary portfolio study, all of whom will have been on the diet for at least 1 year, will be asked to remove a specific food component from their regular dietary portfolio for a 10 week period. After the 10 week period, subjects will be asked return to the normal dietary portfolio with all food components consumed and continue on the long-term dietary portfolio.

Bloods will be taken at weeks 0, 6 and 10 of the food component removal period; and at 2-monthly intervals for 20 weeks prior to and after the 10 week period while on the long-term dietary portfolio with all food components.

Inclusion criteria

• Healthy adult men and postmenopausal women currently enrolled in the long-term portfolio study
• Body mass index <32 kg/m2
• Constant body weight over last 6 months preceding the onset of the study
• Fasting LDL-cholesterol concentration >4.1 mmol/L at diagnosis

Exclusion criteria

• women of child-bearing potential
• major cardiovascular event (stroke or myocardial infarction)
• positive molecular diagnosis of familial hypercholesterolemia
• secondary causes of hypercholesterolemia (hypothyroidism, unless treated & on a stable dose of L-thyroxine, renal or liver disease)
• use of cholesterol-lowering medications
• serum triglycerides >4.5 mmol/L
• blood pressure > 145/90 mmHg
• diabetes and/or major disorders such as liver disease, renal failure or cancer
• major surgery <6 months prior to randomization
• alcohol consumption >2 drinks per day