Ginkgo biloba

Ginkgo biloba, originally found in China, is thought to be the world's oldest living tree, and has been impressing the scientific world for decades.
It's thought to be good for boosting memory, concentration and other brain functions, improving blood circulation to all parts of the body, and useful particularly for people with dementia.
Using the gingko tree leaves, it has been used by the Chinese for thousands of years.
Its impressive results are believed to be due to powerful antioxidants called flavoglycosides, which have been found in studies to have neuroprotective effects on spinal cord injuries in animals.
It also contains substances called terpene lactones which are known to improve blood flow and reduce inflammation. It can increase blood flow around the body by as much as 57%.
Studies also show that ginkgo can help with memory problems caused by dementia or Alzheimer’s disease. It seems to help prevent the progression of dementia symptoms, especially if the dementia is thought to be the result of atherosclerotic vascular disease. It does not seem to prevent dementia or Alzheimer’s, however.
Ginkgo may improve concentration in MS patients with cognitive impairment; improvement in mood, emotional function and cognition in people with Alzheimer's; and people with Down's Syndrome may be able to boost their memory by taking a supplement.
Studies certainly offer evidence that this herb may be an effective brain booster, at least for dementia.
There's good evidence that ginkgo might ease leg pain caused by clogged arteries. It might also help with some other circulation problems. In addition, ginkgo may relieve PMS symptoms, like breast tenderness and mood changes. 
Ginkgo leaf supplements are generally safe. In some people, they can cause headache, dizziness, heart palpitations, nausea, gas, and diarrhea. Allergies to ginkgo can trigger rashes or more serious effects.
If you have a bleeding disorder, or are planning surgery, talk to your doctor before using ginkgo. Don't take ginkgo if you have any medical conditions -- especially diabetes, epilepsy, or fertility problems -- unless your doctor recommends it. Do not eat untreated parts of the ginkgo plant and uncooked ginkgo seeds can cause seizures and death.
If you are taking any medicines or supplements regularly, talk to your doctor before you start using ginkgo supplements. They could interact with blood thinners, aspirin, NSAID painkillers, anti-platelet drugs, anticonvulsants, antidepressants, diabetes medicines, drugs that affect the liver and supplements like garlic, saw palmetto, St. Johns wort, and yohimbe. Ginkgo might reduce the effectiveness of electroconvulsive therapy (ECT.)
You can get ginkgo supplements at chemists and health food shops, but before you take, check for any contra-indications with your GP.