Weight Loss Amplifies DASH Diet Effects on Blood Pressure

A few hours ago I arrived in Hong Kong to speak on the relationship between obesity and hypertension at the 1st International Conference on Abdominal Obesity. While excess weight is probably one of the most important risk factors for high blood pressure, weight loss is certainly one of the most effective treatments.

This relationship between excess weight and blood pressure and how this relationship is affected by a prudent diet, exercise and weight loss is the topic of a paper by James Blumenthal (Duke University, Durham, NC) and colleagues published in this week’s issue of the Archives of Internal Medicine.

The aim of this study was to compare the so-called Dietary Approaches to Stop Hypertension (DASH) diet alone or combined with a weight management program with usual diet controls in 144 overweight or obese participants with prehypertension or stage 1 hypertension (130-159/85-99 mm Hg).

Participants were randomised to four months of their usual diet, DASH diet alone, or DASH diet plus weight management. The DASH diet is reduced in total fat (27%), saturated fat (6%), and cholesterol and contains about 3 times as much dietary fiber, potassium, magnesium, and calcium as the usual diet.

Participants in the weight loss arm were asked to reduce caloric intake by 500 kcal/day and attended weekly 30- to 45-minute small group sessions that also included a weekly cognitive-behavioral intervention as well as supervised exercise sessions 3 times per week at a level of 70% to 85% of their initial heart rate reserve consisting of 10 minutes of warm-up exercises, 30 minutes of biking and/or walking or jogging, and 5 minutes of cool-down exercises.

Participants in the weight management group lost 8.7 kg compared to virtually no weight changes in the other two groups.

The greatest reduction in blood pressure (16.1/9.9 mm Hg) was seen in the DASH plus weight management group compared to only (11.2/7.5 mm) on the DASH diet alone) or 3.4/3.8 mm on the usual diet.

While the study clearly shows that the DASH diet combined with weight loss and exercise can lead to a far greater reduction in blood pressure than the DASH diet alone, there are two important caveats:

1) This is a relatively short term study (4 months) and can therefore not be considered much more than a “proof of principle”.

2) The study was performed at a tertiary care medical center and may therefore have limited applicability to weight or blood pressure management in primary practice.

Nevertheless, the study does remind us of the importance that both diet and weight loss can play in the management of overweight and obese patients with high blood pressure.

Hong Kong