If your blood pressure runs low, someone has told you to eat more salt. A doctor, a forum, a friend who has POTS. It's standard advice and it gets handed out with a lot of confidence.
So we went and read the studies behind it. Not the health-site summaries, the actual trials and the guidelines that cite them. If you're the person being told to salt your food, here's what we found: the biology makes sense, the advice is probably reasonable, and the evidence underneath it is far thinner than anyone lets on.
What goes wrong when you stand up
Stand up and gravity drags something like half a litre of blood down into your legs and gut. A body that's working properly squeezes those vessels, nudges the heart rate up, and you never notice it happened. If you're short on blood volume to begin with, there's less to work with. That's the head rush, the grey vision, the heart hammering on a flight of stairs.
Salt is supposed to fix the volume problem. Sodium holds water in your bloodstream, so more sodium means more fluid retained, which means more blood coming back to your heart when you're upright. It isn't a mysterious mechanism, and it's measurable. The 2015 Heart Rhythm Society guidelines note that blood volume runs low in as many as 70% of people with POTS, the condition where your heart rate climbs sharply every time you stand.
The logic is sound. Whether it works, and how much, is a separate question.
The numbers your doctor is working from
For POTS the recommended amounts are big. The Heart Rhythm Society suggests up to 10 to 12 grams of salt a day, with 2 to 3 litres of water. The Canadian Cardiovascular Society says at least 10 grams of salt and 3 litres of fluid. Ten grams is about two teaspoons of salt, roughly double what an average person eats.
Then you read how those guidelines rate their own advice. The Heart Rhythm Society files it under "Class IIb, Level of Evidence E," which translates to: you might consider this, and we're going on expert opinion rather than data. The Canadian statement calls it a strong recommendation built on low-quality evidence, in those words.
Meanwhile, for neurogenic orthostatic hypotension, the kind that turns up alongside Parkinson's, an expert panel recommends adding just one or two teaspoons of salt to whatever you already eat. Same mineral, same mechanism, an entirely different number.
When expert panels land that far apart, the dose isn't settled science. Which is the first reason your number has to come from your own doctor rather than from an article like this one.
What happened when somebody actually tested it
In 2021 a team at Vanderbilt ran the study you'd want. Fourteen people with POTS and thirteen healthy volunteers each spent six days eating very little salt, then six days eating a lot of it, with everyone measured throughout.
The salt did its job. Blood volume, which had been running about 11% below normal, came back to normal. Standing heart rate dropped. The spike that defines POTS, how far your heart rate jumps when you get up, fell from 60 beats per minute to 46. Even the stress hormones came down.
And the patients didn't feel much better. Their symptom scores improved on paper, but not by enough to count as a real effect. Not one of the nine symptoms they tracked, the dizziness, the fatigue, the brain fog, moved meaningfully. Everyone still met the diagnostic criteria for POTS at the end of it. The researchers wrote that a high-salt diet, "although helpful, is not sufficient to normalize patients with POTS."
Fourteen people is a small study, and it may just have been too small to pick up a real change in how people felt. That's a fair defense. It's also true that the most careful trial we have went looking for the thing patients care about most and couldn't find it.
The fainting studies, and a result nobody expects
The most direct evidence comes from Roger Hainsworth's group in Leeds, who spent years working with people who faint. In 1996 they gave thirty-one patients either salt or a placebo for eight weeks, about 7 grams a day. Seventy percent of the salt group improved, against thirty percent on placebo. They held out longer on a tilt table and their blood volume went up. That's a genuine signal, and it's placebo-controlled, which is rare here.
A follow-up in 2004 found ten of eleven patients improved after two months.
In that 2004 study, salt let patients stay upright longer and improved blood flow control in their brain and limbs. It did not raise their resting blood pressure at all. The paper says so directly: "without affecting blood pressures."
So salt helped, and it didn't help by pushing the number on the cuff upward. It seems to work by improving how well your circulation copes with the act of standing. If you've been picturing salt as a way to nudge a low reading higher, the real story is stranger and more specific than that.
The uncomfortable part
In 2020 a team pooled every interventional study ever run on salt for these conditions, across orthostatic hypotension, fainting, POTS, and the rest, and published it in the American Journal of Medicine. The entire body of evidence came to fourteen studies and 391 people.
Pooled together, patients stayed upright about a minute and a half longer, systolic blood pressure rose around 12 points, and heart rate dropped about 4 beats. Sixty-two percent said their symptoms improved, though that number rests on six studies, ninety-one people, and an average follow-up of forty-four days.
The reviewers graded the evidence low quality. They noted there are no trials at all showing that increased salt is effective or safe over the long run. And they pointed out, politely, that this is a cornerstone recommendation resting on very little.
Three hundred and ninety-one people, followed for about six weeks, behind advice that patients will follow for the rest of their lives.
That doesn't make the advice wrong. Salt is cheap, the mechanism is plausible, the short-term signals are real, and there isn't a great deal else on offer. But "we're fairly confident this helps and nobody has properly checked" is a different sentence from "salt fixes low blood pressure," and you're owed the accurate one.
When more salt is a bad idea
Salt isn't harmless, and the guidelines are blunt about it. If you have heart failure, kidney disease, high blood pressure, or serious swelling in your legs, the advice runs the other way: less salt, not more.
There's a particular trap in neurogenic orthostatic hypotension. The same salt that props your blood pressure up while you're standing can drive it dangerously high while you're lying down overnight. It has a name, supine hypertension, and it's a real risk that gets managed deliberately.
Salt raises blood pressure, which is useful when yours runs low and dangerous when it doesn't. That's why the call belongs to a clinician who knows your diagnosis, and why no article, this one included, should be handing you a number.
So what do you actually do
Ask your doctor for a target, and ask them to include fluid in it. Sodium and water work as a pair, and drinking water on its own can dilute the sodium you already have. That's the step people skip.
Then there's the practical grind of hitting the number. Most electrolyte drinks carry somewhere between 50 and 300mg of sodium per serving, so a target measured in grams means serving after serving. Table salt works fine, though measuring it by the spoonful gets old. Salt tablets sit badly with some stomachs.
That gap is why Saltivate exists. A serving carries 800mg of sodium, well past the token amount in most drinks, so a doctor-set target is easier to reach without a salt shaker on the counter. Raw Unflavored has no sweetener in it at all and stirs into whatever you're already drinking. We're not going to tell you how much to take, because that number isn't ours to give. If you want the practical detail, it lives on our pages for low blood pressure and POTS.
Sources
- Sheldon RS, Grubb BP, et al. 2015 Heart Rhythm Society expert consensus statement on the diagnosis and treatment of postural tachycardia syndrome, inappropriate sinus tachycardia, and vasovagal syncope. Heart Rhythm. 2015;12(6):e41-e63. PMID 25980576. Full text
- Raj SR, et al. Canadian Cardiovascular Society Position Statement on Postural Orthostatic Tachycardia Syndrome (POTS) and Related Disorders of Chronic Orthostatic Intolerance. Can J Cardiol. 2020;36(3):357-372. PMID 32145864. Full text
- Garland EM, et al. Effect of high dietary sodium intake in patients with postural tachycardia syndrome. J Am Coll Cardiol. 2021;77(17):2174-2184. PMID 33926653. Full text
- Gibbons CH, Schmidt P, Biaggioni I, et al. The recommendations of a consensus panel for the screening, diagnosis, and treatment of neurogenic orthostatic hypotension and associated supine hypertension. J Neurol. 2017;264(8):1567-1582. Full text
- El-Sayed H, Hainsworth R. Salt supplement increases plasma volume and orthostatic tolerance in patients with unexplained syncope. Heart. 1996;75(2):134-140. PMID 8673750. Full text
- Claydon VE, Hainsworth R. Salt supplementation improves orthostatic cerebral and peripheral vascular control in patients with syncope. Hypertension. 2004;43(4):809-813. PMID 14981050. Full text
- Mtinangi BL, Hainsworth R. Early effects of oral salt on plasma volume, orthostatic tolerance, and baroreceptor sensitivity in patients with syncope. Clin Auton Res. 1998;8(4):231-235. PMID 9791744. PubMed
- Loughlin EA, et al. Increased salt intake for orthostatic intolerance syndromes: a systematic review and meta-analysis. Am J Med. 2020;133(12):1471-1478.e4. Full text
This article is information, not medical advice. Sodium raises blood pressure, and adding it makes sense only when a clinician has told you to for your specific diagnosis. Don't change your salt or fluid intake on your own, especially if you have heart failure, kidney disease, high blood pressure, or supine hypertension.
