Ginkgo biloba is a popular herbal supplement made from the leaves of a tree found in China and Japan. It is purported to have various health benefits, such as improving memory and concentration. The ginkgo tree leaves are used for medicine and have been used for centuries in Asia.
Some of the researched health benefits of Ginkgo biloba leaf may include:
- Improve blood circulation
- Reduce inflammation
- Help improve cognitive function
- Boost nerve growth and regeneration
- Improve mood
Ginkgo Biloba Research
One study found that people who took ginkgo biloba extract had improved cognitive function, including faster reaction times and longer memory retention. The extract also increased blood flow to the brain.
Standardized extracts from the dried leaves of Ginkgo biloba (GBE) are used as therapeutic drugs to treat memory loss and dementia, including Alzheimer's disease (AD) [13, 14]. Supporting this hypothesis are quite a lot of clinical data showing that G. Biloba enhances cognitive function in patients with AD, the size of effect being similar to the one obtained by other dementia therapies, like acetylcholinesterase inhibitors.
A review of 21 studies found that, in combination with conventional medicines, Ginkgo extract can increase the functional capacity in people with mild Alzheimer's disease (12). Some studies showed significant decreases in cognitive decline among those with dementia using ginkgo, but others failed to replicate the findings.
Another study showed a similar effect in older adults treated with ginkgo extract ( 8 ). Eighty patients were given ginkgo in one recent trial, and 21 patients reported improvements.
A significant improvement in the range of motion without pain was observed in the group receiving 120 mg of ginkgo extract for the 24-week trial conducted at five centers. Study participants in the treatment arm were given 240 mg of ginkgo extract per day for 90 days.
The double-blind, randomized, placebo-controlled trial found that after 24 weeks, there was a significant improvement in the ginkgo-treated group over the placebo. Seven out of the 11 placebo-controlled studies confirmed ginkgo efficacy over placebo for brain insufficiency, with one study being inconclusive.
The authors concluded that ginkgo had positive results for treating cerebral insufficiency, but additional studies need to be conducted for a more detailed evaluation of its effectiveness. A recent review concluded that ginkgo might have protective effects on lipid profiles and that it might support healthy glucose metabolism.
A recent review included 84 separate studies regarding ginkgo's effects on metabolic syndrome. There is insufficient evidence supporting using ginkgo for dementia prevention or treating individuals with mild cognitive impairment.
A review of most studies of ginkgo suggests there are no significant benefits of taking ginkgo for those with the condition. More studies are needed to discover what role ginkgo may have in supporting brain function and treating other diseases.
While some data suggest ginkgo extract may moderately enhance memory in healthy adults, most studies suggest ginkgo does not improve memory, attention, or brain function. Although ginkgo seems safe in modest amounts, studies do not support using this supplement to prevent or delay dementia or cognitive decline.
A more extensive study called the Evaluation of Memory Study with Ginkgo Biloba found the product did not reduce the risk for dementia. Another more comprehensive study found that there was no improvement in memory for 200 adults above the age of 60 taking ginkgo biloba for six weeks.
The randomized trial was conducted in response to one case in which an elderly patient using Ginkgo biloba to improve memory reported an improved erection. Nine clinical trials used EGb761, the standardized extract of Ginkgo biloba, as study medication, with a range of durations from 12 to 52 weeks; EGb761 was administered for 24 weeks in five studies.
In one double-blind, randomized, placebo-controlled trial involving 40 patients with Alzheimer's type senile dementia, daily dosages of 240 mg of EGb 761 were given to the treatment group (Hofferberth, 1994). A meta-analysis was conducted on 2,561 patients diagnosed with AD, which found that treatment with EGb 761 (240 mg/day) over 22-26 weeks improved cognitive decline and dementia.
In the past year, the effects of EGb 761 were investigated by Tan MS and colleagues in 2561 patients diagnosed with AD, dementia, or mixed dementia according to internationally accepted AD diagnostic criteria. Another review evaluated four studies and found significant decreases in a range of dementia-related symptoms when Ginkgo was used for 22-24 weeks (13).
Two clinical trials that are GEM (for Ginkgo Memory Evaluation) test conducted on 3,069 participants aged 75 years or older and suffering from mild cognitive impairment, and the GuidAge study conducted on 2,854 participants aged 70 years or older and reported memory complaints failed to support similar results. Another two-study review assessed the effects of ginkgo extracts on the progression of age-related macular degeneration.
At first glance, these negative results might seem to contradict some, with studies like the GEM trial and the GuidAge study reporting that there was no effect of EGb761(r) on risk for developing dementia, leading some authors to conclusively argue that ginkgo Biloba is ineffective in the prevention of Alzheimer's disease. In the two clinical trials, EGb761 (r) in 120 mg twice daily was not effective at reducing overall dementia or Alzheimer's disease.
In 2007, Canter and Ernst reviewed 15 randomized clinical trials. They found that only one out of five acute and one of six long-term studies reported beneficial effects, suggesting there is no compelling evidence to conclude that G.b has some benefit for cognition for people younger than 60.
The authors concluded that although statistical group analyses within the randomized trials did not support ginkgo for tinnitus treatment, EGb may have some effects on certain patients (Holgers et al., 1994). A trial in 75 individuals evaluated the use of ginkgo extract and treatment with glucocorticosteroid medications to control symptoms of asthma (24). Subanalyses of OR changes by withdrawal rates from adverse events and dosage were also higher for ginkgo Biloba compared with the placebo group (OR = 1.54 [0.77, 3.10] for 120-160 mg/day and OR = 1.90 [0.96, 3.77] for 240 mg/day), but differences were not statistically significant.