Health
What actually moves the number
Video · Mayo Clinic
High Blood Pressure? What to Eat & Avoid (DASH Diet Guide)
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There is a way of talking about blood pressure that makes it sound like eye colour: a fact about a person, fixed at birth, to be managed but never really changed. That is not what the research says. Quite ordinary things move the number, some of them by more than people expect, and because they have been measured in trials we can say roughly by how much.
What follows is the honest version of that arithmetic. It is duller than the version circulating in videos, and it has the advantage of being true.
What has actually been measured
The American College of Cardiology and the American Heart Association keep a table of the changes that have been tested against blood pressure, and what each was worth in the trials. Rounded, and for the upper number:
| The change | Typical fall in the upper number |
|---|---|
| Eating in the pattern known as DASH | About 11 points |
| Regular aerobic movement, 90 to 150 minutes a week | 5 to 8 points |
| Cutting sodium by about 1,000 mg a day | 5 to 6 points |
| More potassium from food, 3,500 to 5,000 mg a day | 4 to 5 points |
| Drinking less alcohol, if you drink | About 4 points |
| Losing weight, if there is weight to lose | About 1 point per kilogram |
Two warnings about that table, and they matter more than the table does. The first is that these are averages across many people, not a promise to any one of them; some readers will see more, some less, some nothing. The second is that they do not add up. You cannot do all six and subtract thirty-odd points, because they overlap — the DASH pattern is already partly a sodium and potassium change, and losing weight is usually partly a movement change.
The kitchen does most of the work
DASH is an unlovely name for a plain idea: more vegetables, fruit, beans, whole grains, nuts and low-fat dairy; less salt, less red meat, less of anything with sugar poured into it. Nobody has to buy a special product to eat that way, and nobody has to eat that way perfectly for it to count.
The potassium line in the table is the one most people have never heard of, and it is the reason the vegetables are on the list at all. Potatoes, beans, spinach, bananas, oranges, tomatoes and plain yoghurt all carry it. It is worth saying plainly that this means food, not a supplement: potassium in a capsule is a different proposition and one that can be dangerous for anyone with kidney trouble or on certain blood pressure medicines. That is a conversation for a doctor, not a shop.
The sodium line is the one where most of the fight actually happens, and not at the table. Most of the salt in an American kitchen arrived inside the food, which is a subject in itself — we wrote about where it hides and how to read a label in another issue.
The part that is not food
Movement is second on the list and it does not have to look like exercise. Ninety minutes a week is a little over twelve minutes a day, which is a short walk most days and nothing more athletic than that.
Sleep belongs here too, though it is harder to put a number on. Blood pressure is meant to fall overnight, and in people who sleep badly it often does not. Anyone who has been told they snore heavily, or who wakes unrested however long they were in bed, has something worth mentioning at the next appointment.
The one change nobody should make alone
If there is a single sentence in this article worth keeping, it is this one: do not stop, skip or reduce a blood pressure medicine on your own, whatever you have read or watched. Blood pressure medicines do not announce themselves — most people feel exactly the same on the day they stop as on the day before, and the risk of stopping is not felt at all until it is. Some of them are also dangerous to stop abruptly rather than taper.
None of this is an argument against the changes above. It is an argument about who decides. Eating better and walking more can, over months, put a doctor in a position to reduce a dose — that happens, and it is a good day when it does. What the doctor is doing in that moment is reading a series of measurements over time. Nobody can do that from a kitchen, and no food or drink clears a blockage that has already formed in an artery. The reason the kitchen matters is slower and less dramatic than that, and it is still the best-supported thing on the list.
Three questions worth asking of anything you watch
A great deal of confident material about blood pressure is published every week, and some of it is very well made. Three questions sort most of it quickly.
Does it name a number and a source? Real findings come with a size — eleven points, four points — and somewhere to check it. "Dramatic results" is not a size.
Does it tell you to keep your doctor? Honest advice about blood pressure always ends up at the same place, because the numbers have to be followed over time by someone who can act on them. Anything that positions itself against your doctor rather than alongside is telling you what it wants from you.
Is something being sold at the end? Not disqualifying on its own. But it should change how carefully you listen to the middle.
Including us
That last question is only worth asking if we are willing to answer it about ourselves. This journal keeps a small shelf of ordinary household things called The Cupboard, and one item on it is a food: a case of bitter corbezzolo honey from the mountains of Sardinia, dark as treacle and eaten there beside aged cheese rather than spread on bread. It is on the shelf because it is unusual and hard to come by, and for no other reason.
It is a food and nothing more. It is not a supplement, it does not appear anywhere in the table above, and not one sentence of this article would change if we stopped stocking it tomorrow.
What to take to the appointment
None of the above is much use without measurements, and measurements taken at home over a week are worth more than the single reading taken in a room that makes everyone nervous. We covered how to take one properly, and what the two numbers mean in a previous issue, and what to write down before you go in in another.
Take the readings, take the list of everything you swallow in a day including the things bought without a prescription, and say the important thing first. Twelve minutes is not long.
Before you change anything
This article is general information, not medical advice, and it cannot know anything about you. Diet, movement, alcohol and sleep all interact with prescription medicines, and potassium in particular interacts with several blood pressure drugs and with kidney disease. Talk it through with the doctor or pharmacist who knows your history before you make a change — and never adjust a prescription on your own.