A review of recent Medline citations finds that five dietary supplements demonstrate evidence of some benefit in the treatment of mild hypertension. CoQ10, fish oil, garlic, vitamin C, and L-arginine all fit the working definition of some evidence of benefit. These agents have shown to be at least as effective as the incorporation of lifestyle modifications. However, these agents should not replace the implementation of recommended lifestyle changes, including proper diet, exercise, and weight loss.
Although the trials mentioned here were published in peer-reviewed journals, many have major limitations. Many of the trials contained a small number of participants and were conducted for short periods of time. The agents with some evidence of benefit should be further studied in large, placebo-controlled, double-blind studies to definitively say that the supplements are effective. In addition, it is important to note that not all of the supplements utilized in the studies were appropriately standardized. Additional studies must be conducted before claiming absolute proven efficacy.
There are no data which demonstrate that the five dietary supplements discussed are more beneficial than currently recommended antihypertensive drugs. These dietary supplements may be considered as adjuvant therapy but not as initial treatment for stage 1 or higher hypertension.
Patients must realize that "natural" products are not necessarily "safe." They must also realize that self-treatment with dietary supplements without the supervision of a health care provider can be potentially dangerous. Because these agents do exert pharmacologic effects on the body, they are capable of producing adverse effects and supple-ment-drug interactions. Despite a few supplements demonstrating evidence for efficacy, several fundamental limitations of essentially all dietary supplement clinical trials must be acknowledged. Many of the studies have a small sample size, are of short duration, and lack a placebo or control group. Additionally, supplements are rarely analyzed for consistent product content before use in a clinical trial. Significant variations have been noted between manufacturer label claims and actual product content.[35,36,37,38,39] Thus, even agents found to have some evidence of benefit by this review will likely have varying efficacy depending on the individual product consumed by the patient. Finally, no dietary supplement has demonstrated evidence for protection against the long-term sequelae of hypertension, such as stroke, myocardial infarction, renal failure, and others.
Our review is not without limitations. Only English-language research published in Medlineindexed journals was included in the review. However, much of the literature on dietary supplements is published in journals not indexed in Medline. Animal data was also excluded, and some dietary supplements may demonstrate antihypertensive efficacy in animal models or have in vitro data suggesting possible antihypertensive actions. Also, only articles published between 1999 and 2003 were included in our Medline search and additional, well developed trials may have been published before this time frame. In addition, many meta-analyses utilized in the research do not clearly state the blood pressure reduction of the placebo groups. Finally, the inclusion of only Medline-indexed articles is a limitation because even Medline-indexed journals have published numerous poor studies of arguable design on the topic of dietary supplements. For example, the lack of standardized products, the possibility of content variation, and the lack of product analysis before and during the clinical investigation may be limitations of the articles reviewed.
It is the responsibility of health care providers to identify and convey concerns about these agents to the public. Before recommending a dietary supplement, a provider should explain the risks that may be associated with these agents and review the potential for product variance as well as lack of effect. Most importantly, health care providers must remember that our first priority is primum non nocere, that is, to do no harm.
© 2004 Le Jacq Communications, Inc.
Cite this: The Natural Treatment of Hypertension - Medscape - May 01, 2004.