STATION 4 OF 7 · SALT AND WATER

Do extra salt and water help?

GUESS FIRST

After 6 days on a high-sodium diet, how did the standing heart rate rise of people with POTS compare with healthy controls?

THE IDEA

Raise blood volume so the heart can slow down.

112BPM · EXAMPLE

This shows the idea of more blood volume. The example heart rates are illustrations. The trials below show what was measured.

A high-sodium diet for 6 days

Garland 2021: randomized crossover with a controlled diet, 14 people with POTS and 13 healthy controls. Extra sodium lowered the rise on standing and raised plasma volume. The rise stayed well above the controls.

People with POTS, high-sodium diet46 bpm rise (study)

Healthy controls19 bpm rise (study)

One dose of oral rehydration solution

Medow 2019: 10 teens with POTS, tested an hour after the dose. Tolerance of simulated standing, on the study's own scale.

Before100 (study scale)

After IV saline135

After oral rehydration solutionabout 156

Each bar shows what that study reported for its own participants.

Guideline: HRS 2015: water 2 to 3 liters and 10 to 12 g of sodium chloride daily, Class IIb (weak recommendation, expert opinion level).

What the trials could not show: The trials are tiny and short, and none tested the 10 to 12 g per day advice used in clinics over months. Symptom and long-term data are missing. A Calgary salt trial (NCT05924646) is recruiting.

Safety: Ask your doctor first if you have high blood pressure, kidney disease or heart failure, since extra sodium and fluid can affect each of them.

Read the trials: Garland 2021, Medow 2019, Snapper 2022 review.