Diet & Fitness

 

In a double-blind study, supplementation with a standardized extract of Ginkgo biloba in the amount of 40 mg three times a day for four weeks partially reversed visual field damage in people with one type of glaucoma (normal tension glaucoma).⁹

 

Ginkgo(Ginkgo biloba) may help treat early-stage macular degeneration, according to small, preliminary clinical trials.¹⁰ Many healthcare professionals recommend 120 to 240 mg of standardized extract (24% ginkgo flavone glycosides and 6% terpene lactones) in capsules or tablets per day.

 

The use of 160 mg per day of a standardized extract of Ginkgo biloba for six months has been reported in a small double-blind trial¹¹ to improve impaired visual function in people with mild diabetic retinopathy.

Most^{12,13,14,15,16,17,18,19} but not all²⁰ clinical trials, many of them double-blind, have found ginkgo supplementation to be a safe and effective treatment for ARCD.²¹

 

Ginkgo(Ginkgo biloba) may help treat early-stage macular degeneration, according to small, preliminary clinical trials.²² Many healthcare professionals recommend 120 to 240 mg of standardized extract (24% ginkgo flavone glycosides and 6% terpene lactones) in capsules or tablets per day.

An extract made from the leaves of the Ginkgo biloba tree is an approved treatment for early-stage Alzheimer’s disease in Europe. While not a cure, Ginkgo biloba extract may improve memory and quality of life and slow progression in the early stages of the disease. In addition, several double-blind trials have shown that ginkgo is helpful for people in early stages of Alzheimer’s disease, as well as for those experiencing another form of dementia known as multi-infarct dementia.^{23,24,25,26,27} Ginkgo has been found to be nearly as effective against Alzheimer's disease as donepezil, a prescription drug used to treat the condition.²⁸ One trial reported no effect of ginkgo supplementation in the treatment of Alzheimer’s disease, vascular dementia or age-associated memory impairment.²⁹ However, the results of this trial have been criticized, since analysis of the results does not separate those patients with Alzheimer’s disease or vascular dementia from those with age-associated memory impairment. A comparison of placebo-controlled trials of ginkgo for Alzheimer’s disease concluded that the herb compared favorably with two prescription drugs, donepezil and tacrine, commonly used to treat the condition.³⁰ Research studies have used 120 to 240 mg of ginkgo, standardized to contain 6% terpene lactones and 24% flavone glycosides per day, generally divided into two or three portions. Ginkgo may need to be taken for six to eight weeks before desired actions are noticed. Ginkgo was not effective for preventing Alzheimer's disease in elderly volunteers with normal cognitive function or in those with mild cognitive impairment.³¹

 

Extensive studies have been done with Ginkgo biloba extracts (GBE) for treatment of intermittent claudication.^32,33 Two double-blind trials found that 120 mg of GBE per day increased pain-free and total walking distance among people with intermittent claudication.^34,35Similar results were seen in another double-blind trial using 160 mg of GBE per day.³⁶ In yet another double-blind trial, two doses of ginkgo extract were compared for six months.³⁷ The researchers studied 60 vs. 120 mg twice daily and found that, while both amounts resulted in significant improvements in pain-free walking distance, the improvements were more pronounced at the higher dose. One double-blind study found that ginkgo extract was not beneficial.³⁸ However, that study lasted only three months, whereas the positive studies lasted six months. It may take longer than three months for ginkgo to have a beneficial effect in people with intermittent claudication.

 

Ginkgo may reduce the risk of atherosclerosis by interfering with a chemical the body sometimes makes in excess, called platelet activating factor (PAF).³⁹ PAF stimulates platelets to stick together too much; ginkgo stops this from happening. Ginkgo also increases blood circulation to the brain, arms, and legs.⁴⁰

Garlic and ginkgo also decrease excessive blood coagulation. Both have been shown in double-blind⁴¹ and other controlled⁴² trials to decrease the overactive coagulation of blood that may contribute to atherosclerosis.

Numerous medicinal plants and plant compounds have demonstrated an ability to protect LDL cholesterol from being damaged by free radicals. Garlic,⁴³ ginkgo,⁴⁴ and guggul⁴⁵ are of particular note in this regard. Garlic and ginkgo have been most convincingly shown to protect LDL cholesterol in humans.

Ginkgo biloba has been reported to improve the circulation in small blood vessels.⁴⁶ For that reason, some doctors recommend ginkgo for people with Raynaud’s disease. One preliminary trial found that 160 mg of standardized ginkgo extract per day reduced pain in people with Raynaud’s disease.⁴⁷ Larger clinical trials are needed to confirm ginkgo’s effectiveness for this condition. Ginkgo is often used as a standardized extract (containing 24% ginkgo flavone glycosides and 6% terpene lactones). Doctors who recommend use of ginkgo often suggest that people take 120–160 mg per day.

Most^{48,49,50,51,52,53,54,55} but not all⁵⁶ clinical trials, many of them double-blind, have found ginkgo supplementation to be a safe and effective treatment for ARCD.⁵⁷

The terpene lactones found in ginkgo extracts, known as ginkgolides and bilobalide, typically make up approximately 6% of the extract. They are associated with increasing circulation to the brain and other parts of the body and may exert a protective action on nerve cells.⁵⁸ ginkgo regulates the tone and elasticity of blood vessels,⁵⁹ making circulation more efficient.⁶⁰ Ginkgo is also well-known for its effect on memory and thinking (cognitive function). It may enhance cognitive performance in healthy older adults,8 in people with age-related cognitive decline, and in people with Alzheimer’s disease.

 

Ginkgo biloba (240 mg per day) may alleviate depression in depressed elderly people not responding to antidepressant drugs.⁶¹ It is unknown if ginkgo could alleviate depression in other age groups. A small, preliminary trial has shown that ginkgo can reduce sexual problems caused by antidepressants like fluoxetine (Prozac), bupropion (Wellbutrin), venlafaxine (Effexor), and nefazodone (Serzone) in men and women.⁶² Double-blind trials are now needed to determine whether ginkgo is truly effective for this purpose.

 

Ginkgo biloba may help some men with ED by increasing blood flow to the penis. One double-blind trial found improvement in men taking 240 mg per day of a standardized Ginkgo biloba extract (GBE) for nine months.⁶³ A preliminary trial, involving 30 men who were experiencing ED as a result of medication use (selective serotonin reuptake inhibitors and other medications), found that approximately 200 mg per day of GBE had a positive effect on sexual function in 76% of the men.⁶⁴

 

Ginkgo biloba may help some men with ED by increasing blood flow to the penis. One double-blind trial found improvement in men taking 240 mg per day of a standardized Ginkgo biloba extract (GBE) for nine months.⁶⁵ A preliminary trial, involving 30 men who were experiencing ED as a result of medication use (selective serotonin reuptake inhibitors and other medications), found that approximately 200 mg per day of GBE had a positive effect on sexual function in 76% of the men.⁶⁶

 

In a preliminary clinical trial, a standardized extract of Ginkgo biloba (GBE) significantly reduced symptoms of vertigo in a group of elderly people with mild cognitive impairment.⁶⁷ Participants were given 40 mg three times per day for one year. GBE has also been reported to significantly reduce vertigo of unknown cause in preliminary⁶⁸ and double-blind⁶⁹ trials. The amounts given were 120 mg and 160 mg per day, respectively, for three months.

 

Ginkgo biloba has been used to treat tinnitus, with mixed results.⁷⁰ The largest placebo-controlled trial to date failed to find any effect of 150 mg per day of ginkgo extract in people with tinnitus.⁷¹ Two smaller, controlled trials have found that standardized ginkgo extract (120 mg per day, containing 24% flavone glycosides and 6% terpene lactones), was effective at relieving the symptoms of tinnitus.^72,73 One trial failed to find ginkgo beneficial, but used less than 30 mg of ginkgo extract per day, an amount unlikely to have any therapeutic effect.⁷⁴

 

Although Ginkgo biloba extract (GBE) has not been studied specifically for its effects in MD, in preliminary studies it has been reported to reduce symptoms of tinnitus, vertigo, and hearing loss due to unspecified inner ear disorders.⁷⁵ Controlled research using GBE is needed to determine whether it is a treatment option specifically for MD.

Ginkgo (Ginkgo biloba) extract was found in a placebo-controlled trial to enhance the HbA1c-lowering effect of the widely used anti-diabetes drug metformin, while not directly altering metabolism of the drug.⁷⁶ In another placebo-controlled trial that included participants whose type 2 diabetes was not well controlled by metformin, adding 120 mg per day of ginkgo resulted in greater reductions in HbA1c and fasting blood glucose and insulin levels, as well as body-mass index (BMI), waist circumference, and abdominal fat, after 90 days.⁷⁷ Clinical research has shown ginkgo extract can improve kidney function in people with type 2 diabetes and early signs of nephropathy (kidney damage), and strengthen retinal blood flow in those with diabetic retinopathy (damage to the visual center of the eye).^78,79 Treatment with the combination of ginkgo leaf plus a traditional Chinese herbal remedy (Liuwei Dihuang Pills) reduced the risks of developing retinopathy or nephropathy in a placebo-controlled trial that included 140 people with type 2 diabetes who were monitored for three years.⁸⁰ Findings from animal studies suggests ginkgo may also have protective effects on nerve tissue and may be helpful in preventing and treating type 2 diabetes-related neuropathy (nerve dysfunction).^81,82

 

The use of 160 mg per day of a standardized extract of Ginkgo biloba for six months has been reported in a small double-blind trial⁸³ to improve impaired visual function in people with mild diabetic retinopathy.

Ginkgo (Ginkgo biloba) extract may be useful to people with type 1 diabetes because of its abilities to raise antioxidant capacity and reduce inflammatory signaling. A standardized ginkgo extract was found to improve insulin production and glucose metabolism and decrease triglyceride levels in an animal model of type 1 diabetes.⁸⁴ Preliminary evidence from a trial in subjects with long-standing type 1 diabetes suggests it may have a role in protecting vision.⁸⁵ Other animal research and a single small, uncontrolled, pilot trial indicate ginkgo may protect nerve function and prove useful for prevention and treatment of diabetic nerve damage (neuropathy).^86,87,88

 

A double-blind trial has shown that standardized Ginkgo biloba extract, when taken daily from day 16 of one menstrual cycle to day 5 of the next menstrual cycle, alleviates congestive and psychological symptoms of PMS better than placebo.⁸⁹ The trial used 80 mg of a ginkgo extract two times per day.

 

Ginkgo biloba extract may also help because it inhibits the action of a substance known as platelet-activating factor,⁹⁰ which may contribute to migraines. No clinical trials have examined its effectiveness in treating migraines, however.

 

A double-blind trial has shown that standardized Ginkgo biloba extract, when taken daily from day 16 of one menstrual cycle to day 5 of the next menstrual cycle, alleviates congestive and psychological symptoms of PMS better than placebo.⁹¹ The trial used 80 mg of a ginkgo extract two times per day.

 

Ginkgo biloba extracts have been considered a potential therapy for asthma. This is because the extracts block the action of platelet-activating factor (PAF), a compound the body produces that in part causes asthma symptoms. A trial using isolated ginkgolides from ginkgo (not the whole extract) found they reduced asthma symptoms.⁹² A controlled trial used a highly concentrated tincture of ginkgo leaf and found this preparation helped decrease asthma symptoms.⁹³ For asthma, 120 to 240 mg of standardized ginkgo or 3 to 4 ml of regular tincture three times daily can be used.

 

In a double-blind study of 52 people with slowly spreading vitiligo, supplementation with Ginkgo biloba extract (standardized to contain 24% ginkgoflavonglycosides), in the amount of 40 mg three times per day for up to six months, resulted in marked to complete repigmentation in 40% of cases, compared with only 9% among those receiving a placebo.⁹⁴ Ginkgo was also found to be effective in a preliminary trial.⁹⁵