13.6: Hypertension, Salt-Sensitivity and the DASH Diet

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Approximately 29% 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 is not a readily employable 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

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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 as described in the first link below. 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.

Web Links

Americans are eating too much salt. So the FDA wants food manufacturers to cut back on sodium.

We've long been told salt is bad for you. Is it really?

This has led to debate because it is quite possible that it is a very real issue whether salt-sensitive individuals can decrease their sodium intake (to reduce their blood pressure) in a food environment where there are extremely limited options that do not contain meaningful sodium levels. Thus, the push has been to reduce sodium levels in the food supply overall to provide more options to those who are salt-sensitive. However, this is a push that benefits a minority of the population. Also, further adding to this is the fact that almost no one knows how he/she responds to sodium/salt and there is disagreement over ideal/optimal intake levels.

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 \(\PageIndex{1}\): 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 \(\PageIndex{2}\): 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 are not 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 \(\PageIndex{1}\): 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 (how well the recommendations are being met) were total fat, fiber, and magnesium, as indicated by their high negative absolute changes.

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References

https://www.cdc.gov/nchs/products/databriefs/db289.htm
Whitney E, Rolfes SR. (2011) Understanding nutrition. Belmont, CA: Wadsworth Cengage Learning.
http://www.nhlbi.nih.gov/health/publ...h/new_dash.pdf
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.