This was followed by random allocation to six months of treatment with active or placebo capsules, four being taken twice a day. Each gelatin capsule contained 500 mg evening primrose oil with 10 mg natural vitamin E (Scotia 05027) or 500 mg liquid paraffin. Liquid paraffin was chosen as the placebo because it is truly inert and is not metabolised or incorporated into cell membranes. The does used was not expected to have any clinical effects on menopausal flushes or other symptoms of the menopause.