Plant sterols in vegetables, fruits and berries

The plant sterol contents of the most important vegetables, fruits and berries available in Finland were determined by capillary gas chromatography. The sample preparation procedure included both acid and alkaline hydrolysis to liberate sterols from their conjugates. The plant sterol contents of fresh vegetables ranged from 51 to 370 mg/kg fresh weight (fw) in samples obtained from retail sale. The highest contents (>300 mg/kg) were measured in broccoli, Brussels sprouts, cauliflower and dill and the lowest (51 mg/kg) in potato. The range of sterol contents on a dry weight (dw) basis was high, 246-4100 mg/kg dw. Considerable variation was also observed when individual samples of some vegetables were compared. Sitosterol was the main sterol (proportion 43-86%) in all vegetables except cucumber and spinach, in which Delta(7)-sterols dominated. The total sterol contents were in the range 116-228 mg/kg fw in all fresh fruits except avocado, which contained more sterols, 752 mg/kg fw. In fresh berries the corresponding range was 60-279 mg/kg fw. The wild berries lingonberry and blueberry were better plant sterol sources than the cultivated berries blackcurrant, redcurrant and strawberry. In fruits and berries the proportion of sitosterol ranged from 61-93% total sterols. On the basis of the results, the contribution of vegetables, fruits and berries to the total average daily plant sterol intake was estimated to be ca 60 mg.