Reviewed: Brinkley TE, Lovato JF, Arnold AM, et al. Effect of Ginkgo biloba on blood pressure and incidence of hypertension in elderly men and women. Am J Hypertens. 2010;23:528-533.

Ginkgo (Ginkgo biloba, Ginkgoaceae) is most often used for treating age-related cognitive decline and mild to moderate dementia. Some concerns regarding ginkgo extracts are that they might cause hypotension or lowering of blood pressure (BP) in some individuals.

This paper consists of a secondary analysis of data from the Ginkgo Evaluation of Memory (GEM) study which was initially published in 2008.¹ It was not a clinical trial designed to study BP effects of a ginkgo extract. The GEM study is a trial of 3,069 subjects (≥ 75 years old) without dementia who were recruited between September 2000 and June 2002 from 4 clinical centers: Johns Hopkins University (Baltimore, Maryland), University of California at Davis (Davis, California), University of Pittsburgh (Pittsburgh, Pennsylvania), and Wake Forest University (Winston-Salem, North Carolina). Subjects were excluded if they had congestive heart disease, or were taking warfarin, antipsychotic medications, or cholinesterase inhibitors. Subjects who were unwilling to reduce their vitamin E intake to 400 IU/day or stop taking ginkgo were excluded. Subjects received either 240 mg/day ginkgo extract (EGb 761^®; Schwabe Pharmaceuticals; Karlsruhe, Germany) or placebo for 6-7 years.

The authors of this article sought to evaluate the effect of ginkgo extract versus placebo on reduction of BP and pulse pressure (difference between the maximum and minimum BPs produced during one heartbeat) in elderly adults.

The primary outcomes were systolic blood pressure (SBP) and diastolic BP (DBP), pulse pressure, and incident hypertension. BP and the use of antihypertension drugs were monitored every 6 months for 6 years. As per the 7th Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7), subjects were classified as hypertensive if any of the following criteria were met: (1) self-reported hypertension and concomitant use of antihypertensive medications; (2) SBP ≥ 140 mm Hg; or (3) DBP ≥ 90 mm Hg. Subjects were classified as normotensive if they had a SBP < 120 mm Hg and a DBP < 80 mm Hg. Prehypertension was defined as a SBP of 120–139 mm Hg or a DBP of 80–89 mm Hg. Incident hypertension was defined as the start of antihypertensive medications or an increase in BP where the subject could be reclassified as hypertensive based on JNC-7 guidelines.

At baseline, 54% of the subjects were hypertensive, 28% were prehypertensive, and 17% were normotensive. Hypertensive subjects tended to be older, female, less educated, had a higher prevalence of diabetes and cardiovascular disease, a lower heart rate, and a higher body mass index. Baseline characteristics did not differ between treatment groups. 

Combining the data from users and nonusers of antihypertensive medications at baseline revealed that both treatment groups had similar significant reductions in SBP and DBP. Pulse pressure significantly decreased from baseline in the entire ginkgo group (P ≤ 0.01) but not the placebo group; nonetheless, the changes were not significantly different between treatment groups. Stratifying the subjects by baseline hypertension status revealed similar findings. Specifically in subjects with hypertension, the decline in SBP, DBP, and pulse pressure was significant for both groups but was not significantly different between treatment groups. In normotensive subjects, there were significant increases in SBP and pulse pressure that did not differ between treatment groups. In prehypertensive patients, there were no changes in the BP variables. The findings were similar when evaluating only the patients who were nonusers of antihypertensive medication.

Using logistic regression, the authors examined the association between treatment and antihypertensive medication use over time in subjects who were nonusers at baseline. Of those who were never users (n = 83), the odds ratio for being a never-user in the ginkgo group was not significantly different from being a nonuser in the placebo group. In other words, these patients never used antihypertensive medication, irrespective of whether they were treated with placebo or ginkgo. Also, there was no difference between treatment groups in the rate of incident hypertension or the number of subjects who went off antihypertensive medication over the course of the study.

The authors conclude that ginkgo extract EGb 761 had no effect on BP or pulse pressure in this population, and there was no evidence that ginkgo reduces the incidence of hypertension. The ginkgo extract EGb 761 has never been used to treat hypertension nor thought useful to do so. This secondary analysis supports this point.