DASH: A Landmark Trial with Enduring Impact
One of the most gratifying aspects of my career has been leading the DASH trial at Hopkins. This trial not only led to new dietary recommendations, it has also propelled the career of numerous Welch faculty and trainees, who continue to analyze its data and publish novel findings.
Lawrence J. Appel, MD, MPH, Director of the Welch Center and Principal Investigator of the DASH trial at Johns Hopkins
The DASH diet (Dietary Approaches to Stop Hypertension) was tested in an NIH-sponsored clinical trial, much of which was conducted at Johns Hopkins. Immediately after publication, the DASH Diet achieved widespread prominence as a highly effective approach to preventing and treating the leading preventable cause of mortality worldwide, hypertension.
The history of this impactful research effort can be traced to the Welch Center. Dr. Paul Whelton, the Founding Director of the Welch Center, and two of his mentees, Drs. Michael Klag, current Dean of the Johns Hopkins Bloomberg School of Public Health, and Lawrence Appel, current Director of the Welch Center, were keenly interested in developing and testing dietary strategies to prevent and control hypertension. At the time, the conventional approach to managing hypertension was to treat elevated blood pressure with drug therapy; the idea of preventing hypertension was promising but unproven.
At a Welch Center journal club in the late 1980’s, Fred Brancati, one of the first Welch Center trainees and, subsequently, Chief of the Division of General Internal Medicine from 2004 to 2013, reviewed an article on the blood pressure lowering effects of dietary potassium. Stimulated by this article, he then worked with Dr. Appel to design HALPIN, a trial funded by the American Heart Association and the first randomized feeding study done by Welch faculty. Based in part on his experience with HALPIN, Dr. Appel successfully competed for an NIH grant to conduct the DASH trial. Soon afterwards, Dr. Edgar ‘Pete’ Miller, a junior faculty member at that time and, currently, Professor of Medicine at the Welch Center, secured a career investigator award from the NIH to lead a DASH ancillary study on the effects of diet on oxidative damage. Other key DASH investigators at Hopkins were Jeanne Charleston, a national expert on recruitment of study participants, and Dr. Ben Caballero, an authority on nutrition and chronic disease.
In 1997, the results of the DASH trial were published in the New England Journal of Medicine. The research community immediately recognized the DASH diet as a highly effective approach to prevent and treat hypertension. For example, among persons with hypertension, the DASH diet was as effective as drug therapy, lowering systolic blood pressure by ~12 mmHg. With remarkable speed, the DASH Diet quickly took off – numerous authoritative bodies, including the influential US Dietary Guidelines, strongly recommended the diet.
An impressive aspect of the DASH research effort has been its widespread and continued benefits to Welch trainees. Nearly 20 years after publication of its main results, Welch trainees continue to publish study results, across a wide variety of topics – from biological mechanisms to public health projections.
The success of the DASH Diet confirmed what the Welch Center has long practiced and believed: meaningful impact stems from a highly collaborative, highly focused, and diverse group of individuals with a common passion and a common goal.