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13.6: Hypertension, Salt-Sensitivity & the DASH Diet

Approximately 27% of American adults have hypertension (high blood pressure), which increases their risk of developing cardiovascular disease1. Salt and/or sodium intake is believed to be a major causative factor in the development of hypertension. However, it is now known that not everyone is salt-sensitive. Salt-sensitive means that a person’s blood pressure increases with increased salt intake and decreases with decreased salt intake. Approximately 25% of normotensive (normal blood pressure) individuals and 50% of hypertensive individuals are salt-sensitive2. Most others are salt-insensitive, and in a small portion of individuals, low salt consumption actually increases blood pressure1. Unfortunately, there isn't a clinical method to determine whether a person is salt-sensitive. There are some known characteristics that increase the likelihood of an individual being salt-sensitive. They are1:

  • Elderly
  • Female
  • African-American
  • Hypertensive
  • Diabetic
  • Chronic Kidney Disease

There is some evidence now suggesting that there may be negative effects in some people who restrict their sodium intakes to the levels recommended by some organizations. The second link describes a couple of studies that had conflicting outcomes as it relates to the importance of salt reduction in decreasing blood pressure and cardiovascular disease. The third link is to a study that found that higher potassium consumption, not lower sodium consumption, was associated with decreased blood pressure in adolescent teenage girls.

Web Link: Report Questions Reducing Salt Intake Too Dramatically
Pour on the Salt? New Research Suggests More Is OK
For Teenagers, Potassium May Matter More Than Salt

To combat hypertension, the Dietary Approaches to Stop Hypertension (DASH) diet was developed.

  • This diet emphasizes: fruits, vegetables, fat-free/low-fat milk and milk products, whole grain products, fish, poultry, nuts
  • It limits: red meat, sweets, added sugars, sugar-containing beverages

As a result the diet is high in: potassium, magnesium, calcium, protein, fiber. The daily goals for the DASH diet are shown below:

Figure 13.61 DASH daily nutrient goals3

To get an idea of what types of foods and how much would be consumed in the diet, an eating plan is shown below.

Figure 13.62 DASH eating plan3

The DASH diet has been shown to be remarkably effective in decreasing blood pressure in those with hypertension. Nevertheless, most people with hypertension aren't following the DASH diet. In fact, evidence from the National Health and Nutrition Examination Survey found that significantly fewer hypertensive individuals were following the DASH diet in 1999-2004 than during 1988-1994, as shown in the table below4.

Table 13.61 Percent of hypertensive subjects in NHANES trial meeting the DASH goals4

Variable

NHANES 1988-1994

(n = 4336)

NHANES 1999-2004

(n = 3821)

Absolute Change (%)

p-value

DASH Accordance

29.3 ± 1.5

21.7 ± 1.3

-7.6

<0.001

Total Fat

42.9 ± 1.8

35.9 ± 2.0

-7.0

0.01

Saturated Fat

20.6 ± 1.2

20.4 ± 1.4

-0.2

0.94

Protein

43.7 ± 2.0

47.7 ± 1.9

4.0

0.73

Cholesterol

26.4 ± 2.2

24.3 ± 1.6

-2.1

0.44

Fiber

20.2 ± 1.5

12.3 ± 0.9

-7.9

<0.001

Magnesium

14.2 ± 1.3

6.4 ± 0.8

-7.8

<0.001

Calcium

19.0 ± 1.6

17.6 ± 2.0

-1.4

0.58

Potassium

12.7 ± 0.9

11.7 ± 0.9

-1.0

0.46

Sodium

17.8 ± 1.5

14.6 ± 1.3

-3.2

0.21

The main components that contributed to the decrease in DASH diet accordance were total fat, fiber, and magnesium, as indicated by their high negative absolute changes.

References & Links

  1. McGuire M, Beerman KA. (2011) Nutritional sciences: From fundamentals to food. Belmont, CA: Wadsworth Cengage Learning.
  2. Whitney E, Rolfes SR. (2011) Understanding nutrition. Belmont, CA: Wadsworth Cengage Learning.
  3. http://www.nhlbi.nih.gov/health/publ...h/new_dash.pdf
  4. Mellen P, Gao S, Vitolins M, Goff D. (2008) Deteriorating dietary habits among adults with hypertension: DASH dietary accordance, NHANES 1988-1994 and 1999-2004. Arch Intern Med 168(3): 308-314.

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