Nutraceuticals with clinically detectable blood pressure lowering effect: a review of available randomized clinical trials and their meta-analyses

AIM: To review and comment the available evidence on nutraceuticals with clinically demonstrated blood pressure (BP) lowering effect. METHODS: We reviewed studies published in English language from 1990 to 2015 on dietary supplements or nutraceuticals claiming to show an effect on human BP. An initial list of possibly effective agents and studies was obtained from the online reference Natural Medicine Comprehensive Database. Using PubMed, we searched agents identified from this list and the MeSH terms "hypertension", "blood pressure", "dietary supplement", and "nutraceuticals" alone and in combination. Then we focused our attention on meta-analyses and randomized clinical trials (RCTs). RESULTS: Beyond the well-known effects on BP of the DASH (Dietary Approaches to Stop Hypertension) and the Mediterranean diets, a large number of studies has investigated the possible BP lowering effect of different dietary supplements and nutraceuticals, the most part of them being antioxidant agents with a high tolerability and safety profile. In particular, a relatively large body of evidence supports the use of potassium, magnesium, L-arginine, vitamin C, cocoa flavonoids, beetroot juice, coenzyme Q10, controlled-release melatonin, and aged garlic extract. The antihypertensive effect of all these nutraceuticals seems to be dose-related and the tolerability is overall good. CONCLUSION: Some nutraceuticals could have a positive impact on BP in humans. Further, clinical research is advisable to identify between the available active nutraceuticals those with the best cost-effectiveness and risk-benefit ratio for a large and long-term use in general population with low-added cardiovascular risk related to uncomplicated hypertension.