Ginkgo biloba: Neurological cure-all or snake oil?

BY Samuel Mathis, MD, Assistant Professor, UTMB

 

In the field of Integrative Medicine, one must always be wary of supplements that claim to have effects that seem impossible to believe. One supplement that has undergone extensive scrutiny recently is Ginkgo biloba. Ginkgo biloba is one of the oldest and most widely used supplements in the world. It has been extensively studied in neurological conditions and is regularly recommended for conditions such as Alzheimer’s disease, vascular dementia, tinnitus, and certain peripheral claudication syndromes (1). It functions as an antioxidant and free-radical scavenger as well as having anti-platelet activities. Some studies have even found that it inhibits beta-amyloid deposition, stimulates choline uptake in the hippocampus, and inhibits age-related loss of certain cholinoreceptors in the brain (1). With its widespread use and numerous beneficial claims, physicians should be aware of this supplement, its uses, risks, and possible benefits to patient care.

There have been numerous studies looking at the effects of Ginkgo biloba over the years. In general, it appears that Ginkgo biloba provides some neuroprotective effects and slows down cognitive decline associated with dementia (2). There have also been studies looking into its effect on cardiovascular and endocrine diseases. Small studies have indicated that there are positive benefits in glucose control when paired with metformin and ginkgo may also decrease plasma lipoprotein(a) which could lower atherosclerosis buildup. However, large studies have generally failed to replicate these effects (2).  Claims regarding ginkgo’s effect on sexual health, vertigo, tinnitus, and even altitude sickness have not been proven with large studies or meta-analyses. Several studies show it may be helpful for psychiatric conditions such as anxiety, schizophrenia, and tardive dyskinesia. However, these studies indicate that ginkgo affects the behavioral aspects of these conditions rather than the underlying neurochemical imbalances (2).

 

Recently, the American Heart Association released a study regarding Ginkgo Diterpene Lactone Meglumine (GDLM), the active compound of Ginkgo Biloba. According to the study, GDLM appears to improve cognitive recovery in ischemic stroke patients if given for 2 weeks after their stroke (3). The study examined over 3,000 patients who were treated with daily injections of the compound following their stroke. This study is different than others as it looked at an injectable form of the supplement rather than oral intake. Additionally, they started the supplement almost immediately after the stroke occurred, and GDLM was given in addition to any blood thinners the patient may have been prescribed. The study found that patients treated with GDLM had a 20% better score on cognitive screenings both at the 14-day mark and the 90-day mark (3). One of the biggest flaws in this study is the short time frame for follow-up.

 

Ginkgo biloba has some risks and contraindications associated with its use. Because of the antiplatelet effects, ginkgo may increase bleeding risk and interact with blood thinners, though no studies have found ginkgo to affect prothrombin time or activated partial thromboplastin time (2). It is not recommended to use ginkgo biloba with NSAIDs or blood thinners due to the increased bleeding risk. Another possible issue with ginkgo is the risk of food fraud. Many supplements contain additional substances that are not labeled. It is important to recommend patients get supplements that have been 3^rd party tested to ensure their quality. Another common risk with ginkgo biloba is contamination with heavy metals. One study found that all ginkgo biloba supplements tested had lead, 54% had arsenic, and 81% were contaminated with cadmium (4). While there were only trace amounts found in the supplements, long-term use of ginkgo biloba could lead to heavy metal toxicity.

 

With conflicting studies, significant herb-drug interactions, and long-term risks, it is understandable why physicians may be hesitant to recommend supplements to their patients. However, we must also recognize the value of these supplements and their historical use. We must continue to research these supplements to identify their benefits and why humans have continued to use them for so many years. Through continued research, we can begin to identify the benefits these supplements offer and how they work in conjunction with contemporary medicine for the benefit of our patients. Ginkgo biloba is not the cure-all that many may espouse it to be, but we may find the truth to its benefits if we are willing to look.

 

References:

1. Sierpina VS, Wollschlaeger B, Blumenthal M. Ginkgo biloba. Am Fam Physician. 2003 Sep 1;68(5):923-6. PMID: 13678141.
2. Nguyen T, Alzahrani T. Ginkgo Biloba. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541024/
3. American Heart Association. (2024, February 1). Active components of ginkgo biloba may improve early cognitive recovery after stroke. ScienceDaily. Retrieved February 5, 2024.
4. Rojas P, Ruiz-Sánchez E, Ríos C, Ruiz-Chow Á, Reséndiz-Albor AA. A Health Risk Assessment of Lead and Other Metals in Pharmaceutical Herbal Products and Dietary Supplements Containing Ginkgo bilobain the Mexico City Metropolitan Area. Int J Environ Res Public Health. 2021 Aug 5;18(16):8285. doi: 10.3390/ijerph18168285. PMID: 34444035; PMCID: PMC8391129.