Clinical trials have demonstrated that ginkgo preparations are effective in the treatment of arterial insufficiency, particularly in the lower limbs and brain. Patients with intermittent claudication showed significant improvements in pain-free walking time and maximum walking distance. Elderly patients with chronic cerebral insufficiency demonstrated a significant regression of major symptoms including vertigo, tinnitus, headache, short-term memory, vigilance and mood changes. Ginkgo has been shown to improve glucose utilisation within the brain. It improves the transmission of nerve impulses and increases alertness by increasing the brain`s alpha wave rhythms and decreasing theta rhythms. It has a demonstrable effect on the venous system too and is used to treat conditions such as varicose veins. Ginkgo alleviates male impotence where the underlying cause is impaired blood circulation to erectile tissue; initial signs of improvement were seen to commence after 8 weeks of Ginkgo biloba supplementation and, after 6 months, 50% of patients had regained potency. Recent research has shown that the extract GBE from the yellow autumn leaves contains a vitamin that strengthens blood vessels, reduces the production of tissue-damaging free radicals and improves cellular energy. The bioflavonoids protect and maintain the integrity of capillary walls, inhibit lipid peroxidation within cell membranes, stabilise the cell membranes involved in the blood-brain barrier, destroy free radicals and inactivate their formation. Ginkgo has been shown to improve eyesight in senile macular degeneration and to neutralise the effects of oxygen free radicals produced in the eyes.