Sodium & DASH Diet: Lowering Blood Pressure Naturally

observational-study PMID: 29141784

Quick Summary: Cutting back on salt and following the DASH diet can significantly lower blood pressure, especially for people with higher blood pressure readings. The study showed the biggest benefits for those with the highest blood pressure.

How Sodium Reduction & DASH Help Your Blood Pressure

This research looked at how reducing sodium (salt) intake and following the DASH diet affect blood pressure. The DASH diet is rich in fruits, vegetables, and low-fat dairy.

Sodium Reduction: Lowering sodium alone helped lower blood pressure.

DASH Diet: The DASH diet also helped lower blood pressure, especially when combined with low sodium.

Combined Power: The best results came from combining a low-sodium diet with the DASH diet.

Study Details

Who was studied: 412 adults with slightly high blood pressure (pre-hypertension or stage 1 hypertension) who weren't taking blood pressure medication.

How long: Participants followed the diets for 4 weeks at a time.

What they took: Participants were assigned to either the DASH diet or a control diet. Within each diet group, they consumed three different levels of sodium: low, medium, and high.

What This Means For You

If you have slightly high blood pressure: Reducing sodium and eating a DASH-style diet could help lower your blood pressure without medication.

Focus on food: Eat plenty of fruits, vegetables, and low-fat dairy.

Read labels: Pay attention to sodium content in packaged foods and try to choose lower-sodium options.

Cook at home: This gives you more control over the amount of salt you use.

Study Limitations

Short study: The study only lasted a few weeks, so we don't know the long-term effects.

Not for everyone: The study didn't include people already taking blood pressure medication or those with very high blood pressure.

Specific group: The study mostly included women and Black participants, so the results might not be the same for everyone.

Key Findings

The study found that combining sodium reduction with the DASH diet led to significant decreases in systolic blood pressure (SBP), particularly in individuals with higher baseline BP. For those with baseline SBP ≥150 mm Hg, the combined intervention reduced SBP by 20.8 mm Hg compared to a high-sodium control diet. Sodium reduction alone lowered SBP by 3.2–8.99 mm Hg depending on baseline BP strata, while the DASH diet alone (under high sodium) reduced SBP by 4.3–10.6 mm Hg. The most pronounced effects occurred in participants with the highest initial BP, suggesting synergistic benefits of both interventions.

Study Design

This was a randomized crossover trial (NCT00000608) involving 412 adults with pre- or stage 1 hypertension not on medication. Participants were assigned to either the DASH diet or a control (typical American) diet. Within each dietary group, they consumed three sodium levels (50, 100, 150 mmol/day at 2,100 kcal) in random order over 4 weeks, with 5-day breaks between phases. BP strata included baseline SBP <130, 130–139, 140–149, and ≥150 mm Hg.

Dosage & Administration

Sodium intake was controlled at 50 mmol/day (low), 100 mmol/day (intermediate), and 150 mmol/day (high), maintained at a constant caloric intake of 2,100 kcal/day. The DASH diet emphasized fruits, vegetables, low-fat dairy, and reduced saturated fat/cholesterol, while the control diet reflected average U.S. consumption. Diets were provided to participants for each phase, ensuring adherence.

Results & Efficacy

Sodium reduction alone (control diet):
SBP decreased by 3.20, 8.56, 8.99, and 7.04 mm Hg across BP strata (<130, 130–139, 140–149, ≥150 mm Hg), with a significant trend (p = 0.004).
DASH vs. control (high sodium):
SBP differences were -4.5, -4.3, -4.7, and -10.6 mm Hg across strata, but the trend was not statistically significant (p = 0.66).
Combined low sodium-DASH vs. high sodium-control:
SBP reductions were -5.3, -7.5, -9.7, and -20.8 mm Hg, with a highly significant trend (p < 0.001).
The greatest effect was observed in participants with baseline SBP ≥150 mm Hg.

Limitations

Short intervention duration (4 weeks per phase), limiting insights into long-term adherence or effects.
Excluded individuals on antihypertensive medications, reducing generalizability to treated populations.
Baseline BP strata did not include SBP >160 mm Hg, leaving a gap in understanding effects for severe hypertension.
Demographics skewed toward women (57%) and Black participants (57%), potentially limiting applicability to other groups.

Clinical Relevance

For adults with pre- or stage 1 hypertension, combining sodium reduction (<50 mmol/day) with the DASH diet can yield clinically meaningful SBP reductions, especially in those with baseline SBP ≥150 mm Hg. These findings support dietary interventions as a first-line approach for managing mild-to-moderate hypertension. However, the lack of data in patients with SBP >160 mm Hg or those on medication underscores the need for personalized medical advice. Practically, this study highlights the importance of both dietary patterns and sodium intake in BP management, with potential to reduce reliance on pharmacotherapy in high-risk groups.

Note: This analysis is specific to the provided study details. Further research is required for severe hypertension and medicated populations.