Ginkgo Biloba Correct Dosages

I have heard different theories regarding the correct dosage for ingesting Ginkgo Biloba and would like clarification on this issue. Currently I am taking a 40 mg extract three times daily along with a single dosage of B complex. Although I seem to benefit from extra energy along with acute memory and mental enhancement, should I increase my dosage of Ginkgo Biloba to fully benefit from this herb?

From the point of view of negative side effects, two studies suggest that even high dosages or injections cause few problems. In one study on 2,855 patients taking ginkgo extract about 3.7% experienced minor gastric upset that disappeared when ginkgo was stopped. In the other, 8,505 patients took ginkgo for six months and only 0.4% suffered minor side effects, mostly stomach upset.
Even high doses of ginkgo do not affect hormonal balance in men, sugar metabolism, genesis of blood cells, or the functioning of the liver or kidneys, according to Christopher Hobbs' research. Hobbs' book, "Ginkgo: Elixir of Youth" (available from Richters) describes the properties, uses and safety of ginkgo in detail.
Hobbs does not mention another possible side effect of taking ginkgo. In some people, it can cause headaches because it increases the flow of blood and pressure in the brain.
Whether increased doses increases the beneficial effects is not well established. In one study (mentioned in Hobbs' book) six young volunteers took up to 600 mg of the standardized extract and reported increased mental alertness, with stronger alpha and beta brain waves lasting for 4.5 hours. It seems that lower doses benefit the elderly, but younger patients must take larger doses to see an effect. We are not aware of any study that establishes the long term benefit and safety of taking higher doses.