In this diet, the acronym “DASH” stands for “Dietary approaches to Stop Hypertension.” This diet has been formulated especially for people who are at risk of high blood pressure or who already have the condition. The diet is intended to support the medical therapies such individuals may have been prescribed and to benefit their overall health.
The term blood pressure refers to the pressure exerted on the walls of vessels as blood flows through them to reach parts of the body. The optimum levels of blood pressure, as measured by a sphygmomanometer, are 120/80 mm Hg, where the 120 refers to the systolic blood pressure and the 80 to the diastolic blood pressure.
Systolic blood pressure is the pressure exerted on the walls of the arteries as the heart beats and blood is pushed through them. The diastolic reading denotes the pressure in the arteries between two heartbeats, while the heart is at rest.
Studies have been conducted to assess the possible role of diet in heart disease including its effects on blood pressure. Minerals such as calcium and magnesium have been studied extensively in isolation but no concrete benefits in supplementing just one of these minerals has been shown.
However, The National Heart, Lung, and Blood Institute (NHLBI) conducted several studies that tested the effect of the diet overall in protecting against hypertension, rather than looking at the effects of single nutrients. The first of these studies was the Dietary Approaches to Stop Hypertension (DASH) study.
The DASH diet has the following features:
- Low in saturated fat
- Low in cholesterol
- Low in total fat
- Rich in fruits and vegetables
- Rich in low fat dairy foods
- Rich in dietary fibres or wholegrain products
- Includes fish, poultry, and nuts
- Low in red meat, sweets, and sugar-containing beverages
- Overall, the diet is rich in magnesium, potassium, calcium, protein and fibres.
For the study, 459 adults with a systolic blood pressure of less than 160 mm Hg and a diastolic pressure of 80–95 mm Hg were included. Of these, around 27% had high blood pressure, 50% were women and 60% were African Americans.
The participants were divided into three groups that each followed a different eating plan. The first diet plan was made up of what most Americans consume; the second was the same but with higher levels of fruits and vegetables; and the third was the DASH diet. For all three diets, the daily intake of salt was around 3000 milligrams.
Results showed that both the diet that contained additional fruits and vegetables and the DASH diet reduced blood pressure compared with the first diet. However, the DASH diet achieved the best results, with reductions in blood pressure achieved within just two weeks of starting the plan.
Reviewed by Sally Robertson, BSc