Pycnogenol Improves Microcirculation, Retinal Edema, and Visual Acuity in Early Diabetic Retinopathy
Steigerwalt R, Belcaro G, Cesarone MR, et al
J Ocul Pharmacol Ther. 2009;25:537-540
This double-blind, placebo-controlled trial was designed to test the protective effects of Pycnogenol®, an extract of French maritime pine bark that stimulates endothelial nitric oxide to facilitate vasodilatation. Pycnogenol® was evaluated for its effects in early stages of retinopathy characterized by mild to moderate retinal edema in the absence of hemorrhage or hard exudates in the macula center. Inclusion criteria included diabetes diagnosed at least 4 years previously; good glycemic control (hemoglobin A1c < 7%); and a moderate degree of retinopathy characterized by macular edema, retinal swelling, and the presence of minor exudates and hemorrhage. Persons with proliferative retinopathy, previous laser treatment, or hypertension requiring medical treatment were excluded.
Eligible patients were randomly assigned to 150 mg Pycnogenol® (n = 24) in the morning after breakfast or placebo (n = 22) for 2 months. There were no significant differences between the treatment and control groups at baseline in terms of age, sex, glycemic control, or duration of diabetes. More important, there was no difference in baseline visual acuity, retinal blood flow, or retinal thickness. The following variables were investigated:
- Visual acuity using the standard Snellen Chart;
- Diabetic retinopathy by ophthalmoscopy following pupil dilation;
- Retinal blood flow (quantitatively and noninvasively) by color duplex scanning;
- Retinal thickness using resolution ultrasonography at 14 MHz; and
- Ultrasonography evaluation twice by 2 experienced physicians.
Visual acuity in the group receiving Pycnogenol® significantly increased from a baseline average of 14/20 to 17/20 after 2 months. Because no significant change was found in the control group, the difference at the end of the study was statistically significant between the 2 groups.
Pycnogenol® significantly improved both systolic and diastolic retinal blood flow, expressed as flow velocity at the central retinal artery. Among the subset with moderate (as opposed to mild) retinal edema, retinal thickness decreased significantly in the Pycnogenol® group but not in the control group.
There is no shortage of herbal or plant extract supplements available for just about anything that ails a patient. Many manufacturers make unsubstantiated claims, and in the rare case that those claims are evaluated scientifically, they typically fail to hold up. Pycnogenol® claims beneficial effects in cardiovascular health, skin care, cognitive function, diabetes health, inflammation, sports nutrition, asthma and allergy relief, and menstrual disorders, among others.
Some of the manufacturer’s supporting documentation is less than convincing, but studies in relatively obscure journals do seem to provide evidence that Pycnogenol® improves retinopathy and reduces risk factors for cardiovascular disease; blood glucose might also be improved.
In the current study, the authors conducted a randomized trial that also demonstrated an ophthalmologic benefit. However, patients underwent a diet and exercise program, so the benefits of Pycnogenol® could not be isolated. In addition, the study was limited by the extremely selective sample: Participants had a mean age of about 52 years and had had a diabetes diagnosis for a mean of about 6.5 years, making them quite young at diagnosis. More important, patients with hypertension were excluded. It is actually somewhat surprising that they found 46 patients with diabetes for at least 4 years who were not hypertensive! Thus, it is not clear whether the results would apply to the more general diabetes patient.
The results suggest that further research into the potential benefits of Pycnogenol® is indeed warranted.