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Diabetes and Hypertension: Where an Essential Mineral Fits in the Americas’ Health Debate

The Americas are trying to subtract their way out of diabetes and hypertension, and the arithmetic doesn't appear to be working. You know the script, because your doctor and your health ministry both recite it. Go easy on the salt, go easier on the sugar, and expect a prescription the day that stops being enough. Nowhere in that script is there a line about what has dropped off the plate, and magnesium is the plainest case of it.

A Debate Built on Subtraction

Glucose handling and blood pressure both lean on the mineral, and yet something like four in five city dwellers across Latin America seem to be eating too little. Magnesium won't cure either disease, and this column won't pretend otherwise. A health debate that ignores it, though, is probably reading half the ledger.

The stakes are large enough to justify the question. A special report in the Pan American Journal of Public Health counts hypertension and diabetes as contributors to nearly a third of all deaths in the Americas each year, some 2.3 million. Anything that touches both conditions, even modestly, deserves a hearing before it's dismissed.

Four in Five, Measured Once

The four-in-five figure comes from a dietary survey of 9,216 people living in the cities of eight Latin American countries, Argentina, Brazil, Chile and Colombia among them. Researchers recorded what each person ate on two separate days and set it against what a body needs. For iron and most B vitamins, fewer than one in ten fell short. Magnesium was another story, with 80.5% of people short. Across the nutrients measured, the people who fared worst were those with less schooling and those already overweight or obese. Those are the households where diabetes and high blood pressure tend to turn up next, and they're eating the diets thinnest in minerals.

Two cautions belong beside that number. A food diary estimates what someone ate and can't show what the body absorbed or stored. The diaries are also old. People filled them in during 2014 and 2015 and the results didn't reach print until 2024, which may tell you how urgent anyone thought the question was. Planners are left with one big snapshot of mineral intake in the region's cities, and nothing in the published record suggests a second is on the calendar.

What the Mineral Does and Why Blood Tests Miss It

Why should a shortage of one mineral matter to two diseases? Because both run through machinery that magnesium helps operate. The reference sheet that the US National Institutes of Health keeps for clinicians describes it as a working part of more than 300 enzyme systems, among them the ones that govern blood glucose control and blood pressure regulation. In principle, a body running short handles the same meal less well and pushes blood through tighter pipes. As theories go, it's a tidy one. If you've been told to watch your sugar or your pressure, though, the chances are that nobody mentioned the mineral.

ICL, a minerals producer that supplies magnesium to food and supplement makers, sets out the role of magnesium in metabolic health in terms a patient could follow, and one detail in its account changes how the whole problem looks. About 60% of the body's magnesium is locked in bone, most of the rest sits inside muscle and organs, and only around 1% travels in the blood. A routine blood test therefore samples the smallest reserve the body has. It's quite possible to be running low while the laboratory report says everything is in range.

Clinicians will recognize the practical consequence. The NIH sheet concedes that blood levels correlate poorly with the body's total stores and that no single test is considered satisfactory, and it notes that magnesium isn't part of routine electrolyte testing in hospitals and clinics. A normal result may therefore rule out less than it seems to. The cheaper instrument is a question. How many days last week did you eat beans, or anything green, or bread that wasn't white? A primary care team will often learn more from the answer than from the lab slip.

Where the Evidence Runs Thin

The evidence that more magnesium prevents disease is thinner than its enthusiasts tend to admit. When United States regulators agreed in 2022 to let food and supplement labels connect magnesium with a lower risk of high blood pressure, they insisted the wording carry its own caveat, and the approved sentences call the science “inconsistent and inconclusive.” The agency wasn't being coy. It had reviewed the studies and found them pointing in different directions. Trials of tablets bear that out. One review of 12 trials in people with hypertension found that supplements brought the diastolic reading, the lower of the two numbers, down by about two points. That is a real effect and a small one.

Long-term observation is a little kinder. Take the ten studies that between them tracked more than 180,000 adults. Pooled, they show about 5% less hypertension for every extra 100 milligrams of magnesium a person eats in a day, though the margin of error on that figure runs all the way out to no effect at all. Look at where the ten were done, too. Eight were American, one was Dutch and one was Mexican. Latin America is barely present in the evidence it is being asked to weigh.

Type 2 diabetes looks more promising. One paper pooled forty long-term studies, more than a million people in all, to look at dietary magnesium intake and type 2 diabetes risk, and the same extra 100 milligrams a day went with a 19% lower risk. It found nothing clear for cardiovascular disease as a whole. Anyone tempted to treat the mineral as a general tonic should sit with that second result for a while. These are still associations, and it isn't hard to see how they might mislead. The person eating the most magnesium is the one with lentils on the stove and spinach in the fridge, who probably also walks more, smokes less and sees a doctor sooner.

Small trials inside the region complicate the picture further. The NIH summary describes one in Brazil and one in Mexico in which magnesium supplements improved blood sugar control in people with type 2 diabetes, and a third, in patients already on insulin, in which they made no difference. On that record the American Diabetes Association has held that there isn't enough evidence to recommend magnesium routinely for blood sugar control.

A Way of Eating, Hiding in the Data

Does that sink the premise? Partly, and the damage is instructive. A missing ingredient ought to be replaceable with a tablet, and the tablet trials came back mixed enough to earn that shrug from the regulator. So what are the long-term studies picking up? More plausibly the old plate itself, rice or tortillas with beans and something green beside them. Run rice or wheat through a mill and the bran comes off with most of the magnesium still in it, which is how half a cup of cooked brown rice ends up with about 42 milligrams in the NIH tables and the same scoop of white with about 10. Half a cup of black beans has roughly 60. Read like that, the 80.5% is a measure of how far the region's cooking has drifted from its own kitchens, more than it is a deficiency waiting for a remedy.

None of this would surprise a dietitian. The blood pressure diet they've been handing out for years, DASH, is mostly vegetables, fruit and low-fat dairy, and when it was put through trials the top number fell by 5.5 points on average. Magnesium tablets have typically managed less. DASH raises potassium and calcium along with magnesium, mind you, so nobody can say which mineral earned how much of the credit. A dietitian doesn't need the answer, because the plate they recommend is the same either way.

Ask a chemist why spinach is green and you'll get magnesium in the answer, because one atom of it sits at the heart of every chlorophyll molecule. A diet short of the mineral is usually a diet short of plants.

Brazil's Uncomfortable Numbers

Brazil shows what subtraction achieves when it works. Ask adults in the country's state capitals whether a doctor has ever told them they have diabetes, as the health ministry's pollsters do every year, and in 2006 about one in eighteen (5.5%) said yes. By 2024 the answer was yes from one adult in eight, a diabetes rate of 12.9%. High blood pressure went the same way, if less steeply, from 22.6% of adults to 29.7%.

Over much the same period Brazilians did what the campaigns asked of them. The near-daily soda habit, soft drinks or artificial juice on five or more days a week, was something 30.9% of adults owned up to in 2007 and only 16.2% did in 2024. Leisure exercise went the right way as well. Three adults in ten were getting 150 minutes a week in 2009, and by 2024 it was better than four in ten (42.3%). Fruit and vegetables are the exception. About a third of adults ate them regularly at the start (33%) and about a third still do (31.4%).

This is a telephone survey of the state capitals, so it only knows what people there were willing to say about themselves. An aging population explains part of the rise, and wider testing may explain some more. It's still an uncomfortable result for anyone who believes the job is mostly a matter of taking things away. The indicator that stood still is the only one that measures what people add to the plate.

Where Treatment Succeeds, and When It Arrives

None of this is an argument against the pharmacy. The region has become good at treatment and deserves credit for it. A single primary care program, running in more than 10,000 clinics, now treats more than six million people for high blood pressure in 28 countries, and six in ten of them have it under control. Worldwide, only one in five people with the condition can say the same. That is progress. Most of it also arrives after the damage has begun.

There is an opening inside that program for the people who run it. The H in the program's name, HEARTS, stands for healthy-lifestyle counseling, and it comes before the letters for protocols and medicines. Whoever runs those sessions is presumably already asking about salt. Two more questions, one about beans and one about whole grains, would cost a minute, and written down they'd start the intake record the region doesn't have.

Labels That Count Only Excess

Prevention has its own blind spot, and you can see it on a supermarket shelf in Santiago or Buenos Aires. By 2022 six countries, beginning with Chile in 2016, had adopted front-of-package warning labeling, and Argentina's black octagons flag excess sugars, fats, sodium and calories. No symbol exists for absence. You could fill a basket with products that carry no warning at all and still go home short of magnesium, and nothing printed on the packaging would tell you.

Sugar has an industry to tax and salt has a shaker to blame. A missing mineral offers no villain, which makes it poor material for a campaign. Regulators could still take a modest step. Argentina's rules already bar products that carry an octagon from claiming to be “rich in fiber,” so the authorities are clearly willing to police what a label says about a food's virtues. Whether a label should also report the minerals a food supplies is a question worth putting to them.

The Scale of What Goes Unmeasured

Scale makes the omission harder to excuse. A hemispheric count in 2022 put the number of people living with diabetes in the Americas at 62 million, and that was only the diagnosed. Its authors reckoned that roughly 40% of people with the disease had never been told they had it, and they expected the total to hit 109 million by 2040. Only 12 countries could offer all six basic tools for managing the disease in their public clinics, equipment for measuring blood glucose among them. Ask yourself how likely it is that a system short of glucose meters will go looking for a mineral an ordinary blood test can't reliably find.

Why a Pill Is the Wrong Shortcut

The market's answer to a shortfall is a pill, and here the argument has to turn on itself again, because for many of the people concerned a pill may be the wrong answer. Diabetes is the leading cause of chronic kidney disease in the hemisphere, and it's the kidneys that clear surplus magnesium from the body. So the patients with the most to gain from a better intake include the ones least able to take it safely in concentrated form.

What does that mean at the pharmacy counter? Start with the number on the NIH sheet, 350 milligrams, which is as much as an adult should take in a day from tablets and medicines put together. Then ask about the kidneys before selling anything, since a weak pair can let magnesium build up to toxic levels. The same sheet says who is likeliest to be running low. Type 2 diabetes is on the list, apparently because the extra sugar passing through the kidneys carries magnesium out with it. Some water pills taken long term do something similar, and so, after a year or more, can the acid-suppressing drugs sold for heartburn. Those are the patients in whom a conversation about intake is most likely to pay off. Food carries far less of that risk. Food is also much harder to change.

Fields, Staples and Prices

The researchers behind the eight-country survey didn't ask for supplements. They asked for fortified staples, for crops grown to carry more minerals, and for policies that put nutrient-rich food within financial reach of poorer households. The second of those starts in the soil, since a bean can only pass on what the plant managed to take up. These are slow measures with no launch date and no ribbon to cut. Follow health and science coverage from the region for a month and count how often any of them appears beside the stories about new injections and new labels.

Each has a professional constituency that could move without waiting for a perfect trial. An agronomist or an extension officer could start reporting how much of the mineral a crop carries, the way they already report yield. Managers of school meals and other public food purchasing can weight contracts toward beans, whole grains and leafy vegetables. The cheapest step, and probably the one to take first, belongs to survey directors, who could add mineral intake to national risk-factor questionnaires such as Brazil's. None of the other measures can be judged without that record.

What to Ask Before the Evidence Is In

Nobody may ever know how much of the hemisphere's diabetes and hypertension a better-fed population would have been spared. A trial that could settle it would need to run for years, use food instead of tablets, and take place in the cities where the shortfall is deepest, and beans have no patent holder to pay for it.

That is no reason to wait. If you live with either condition, ask at your next appointment what your diet supplies before you ask about a supplement, and ask about your kidneys before you take one. Clinicians can add the diet question to the visit this week. Anyone who plans programs or writes budgets should find out when their country last measured what its people eat, and press for the next survey to count minerals.

The debate will carry on with the instruments it has. The warning labels reach more shelves and the clinics get better at catching what has already happened. Four in five people in those eight countries, meanwhile, were short of a mineral that an ordinary lunch used to supply, and it still isn't clear whose job it is to find out whether that remains true.