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More than two-thirds of American adults do not have enough magnesium.
A 2026 analysis of U.S. adults participating in the National Health and Nutrition Examination Survey found that 67.8 percent had serum magnesium concentrations below 2.06 mg/dL, the threshold the researchers used for chronic latent magnesium deficiency. That number is remarkable, particularly because serum magnesium may actually be a relatively insensitive way of detecting inadequate magnesium stores.
Magnesium deficiency is generally assessed by measuring magnesium in the blood, yet less than one percent of the body’s magnesium is found in serum. Most magnesium is stored in bone and within cells. The body also regulates circulating magnesium rather tightly, meaning that serum concentrations do not necessarily provide a complete picture of magnesium stores. A normal blood test does not necessarily mean that the body’s magnesium stores are adequate.
There is an important issue concerning how we define deficiency. The researchers used a higher serum magnesium cutoff than is conventionally used to diagnose clinical hypomagnesemia. Their threshold of 2.06 mg/dL has been proposed as a better marker for chronic latent magnesium deficiency, based in part on studies showing physiological changes and increased health risks at magnesium concentrations that conventional laboratory ranges may still classify as normal. In other words, by the time someone crosses the conventional threshold for frank hypomagnesemia, we may be looking at the far end of the problem rather than its beginning.
There is even more reason to take the finding seriously. We already know from dietary surveys that Americans aren’t consuming enough magnesium. Analysis of NHANES dietary data found that 48 percent of Americans consumed less magnesium from food and beverages than their Estimated Average Requirement.
These are two different measurements asking two different questions, but they point in the same direction. One finds widespread inadequate dietary intake. The other suggests that suboptimal magnesium status may be even more common.
Why should we care?
Because magnesium isn’t a minor nutritional accessory. It is involved in hundreds of enzymatic reactions and some of the most fundamental processes keeping us alive. Magnesium is required for the production and utilization of ATP, the energy currency of the cell. It plays essential roles in protein synthesis, DNA and RNA metabolism, glucose regulation, muscle and nerve function, vascular tone, cardiac electrical stability and bone metabolism. In the brain, magnesium helps regulate neuronal signaling and synaptic plasticity, processes fundamental to learning, memory and cognitive function.
Low magnesium status has been associated with cognitive impairment and dementia, while experimental studies have shown that increasing magnesium concentrations in the brain can enhance synaptic plasticity and improve learning and memory. Much of the early work involved magnesium-L-threonate, a form developed specifically to increase magnesium availability in the brain. The evidence has now progressed beyond animal studies.
Randomized, placebo-controlled human trials have reported improvements in several measures of cognition and memory, including working and episodic memory, following magnesium-L-threonate supplementation. What has not yet been established is whether these cognitive effects translate into prevention or treatment of Alzheimer’s disease or other dementias.
Human studies also suggest that magnesium status differs in people with Alzheimer's disease. A meta-analysis of 21 studies found significantly lower serum and plasma magnesium in Alzheimer's patients than in healthy controls. Perhaps more interestingly, postmortem studies of human brains have reported lower magnesium concentrations in Alzheimer's-affected regions, including the hippocampal region, entorhinal cortex, and frontal cortex. These findings do not prove that magnesium deficiency causes Alzheimer's disease. Neurodegeneration itself could alter magnesium metabolism. But prospective evidence makes the relationship harder to dismiss: in the Rotterdam Study of 9,569 initially dementia-free adults, low serum magnesium was associated with a 32 percent greater subsequent risk of dementia.
Which raises an obvious question.
Why are so many Americans apparently running short of a mineral this fundamental to human biology?
There isn’t one answer. The medical system likes to point out that medications, gastrointestinal disease, diabetes, alcohol use, kidney loss, and aging can all affect magnesium status.
But there is another explanation sitting directly in front of us.
The food industry removed much of the magnesium from our food.
Big Ag removed much of the magnesium from food
When we wrote Homesteading for Health, we spent considerable time examining something largely missing from modern discussions about nutrition. Food isn’t simply protein, carbohydrate, and fat.
Food contains minerals.
And the nutritional composition of our food is not fixed.
The nutritional quality of our food has changed. Evidence accumulated over decades shows that modern high-yield agriculture can produce more food per acre while reducing the concentration of minerals in that food. Historical USDA comparisons found substantial declines in several nutrients in fruits and vegetables between 1950 and 1999. Long-running agricultural experiments provide even stronger evidence. The Broadbalk Wheat Experiment in England, which has been continuously cultivated and studied since 1843, has documented significant declines in magnesium, zinc, iron, and copper concentrations in wheat grain associated with modern high-yield varieties. As crop yields increased, mineral concentrations often fell, a phenomenon researchers call the dilution effect.
But yield is only part of the story. Plants do not simply vacuum minerals out of dirt. Healthy soil is a living biological system in which bacteria, fungi, and plant roots work together to make minerals available to the plant. Modern tillage, heavy fertilizer use and other intensive practices disrupt those relationships, particularly the mycorrhizal fungal networks that extend the effective reach of plant roots. A soil may therefore contain magnesium and other minerals on a laboratory assay while becoming less biologically effective at delivering them into the crop.
What matters isn’t simply whether magnesium exists in the dirt. What matters is whether it makes its way from the soil into the food and ultimately into us.
Then we take the food we produce and process even more magnesium out of it.
We know exactly where much of it went.
Industrial milling removed it from our food
Again, in Homesteading for Health, we document that much of the issue stems from the production of processed flour. The wheat kernel consists of the bran, germ, and endosperm. The bran and germ contain a disproportionate share of the grain’s minerals, including magnesium. Making refined white flour removes those portions of the kernel.
The result can be a dramatic reduction in magnesium.
And then comes one of the stranger ironies of our modern food system.
We call the resulting product “enriched flour.”
Iron and selected B vitamins are added back after milling, and folic acid is added to most enriched grain products.
Magnesium generally isn’t.
We take a naturally magnesium-containing food, remove much of its magnesium, replace a selected handful of the nutrients lost during processing, and call the finished product enriched.
Then we make refined flour a foundation of the American diet.
Perhaps the magnesium problem isn’t quite so mysterious after all.
Where Did the Magnesium Go?
The best natural sources of magnesium aren’t particularly exotic.
Pumpkin seeds, chia seeds, almonds and other nuts, beans, lentils, whole grains and dark leafy vegetables are all good sources. Magnesium is, after all, at the center of the chlorophyll molecule. Green plants are therefore an obvious place to find it.
The modern American diet has moved in almost exactly the opposite direction.
Whole grains became refined grains. Beans and legumes became less central to many meals. Nuts and seeds became optional snacks rather than routine foods. Fresh vegetables increasingly compete with highly processed products made primarily from refined flour, starch, sugar, and industrial oils.
The result is an interesting nutritional paradox.
Americans can consume more than enough calories while remaining poorly supplied with micronutrients.
We can be overfed and undernourished at the same time.
Then There Is the Brain
For years, magnesium was discussed primarily in relation to muscle function, bone, cardiovascular health, and metabolism. Its role in cognition received considerably less public attention.
That has changed.
Magnesium is involved in neuronal signaling and synaptic plasticity, the process through which connections between neurons change in response to experience. These mechanisms are fundamental to learning and memory.
Animal experiments produced some striking early findings. Increasing brain magnesium concentrations improved measures of synaptic plasticity, learning, and memory, and experimental work with magnesium-L-threonate generated particular interest because this compound was developed to increase magnesium availability in the brain.
There are also observational human data connecting magnesium status with cognitive health and dementia. A 2024 systematic review examined three randomized controlled trials and 12 cohort studies. The cohort evidence suggested relationships between magnesium status and cognitive outcomes. Interestingly, the researchers also found a U-shaped association between serum magnesium and dementia or cognitive impairment, with approximately 0.85 mmol/L appearing to represent an optimal concentration in the available cohort data.
That last observation is important.
More is not always better.
The objective isn’t to consume enormous amounts of magnesium. It is to have enough.
Magnesium-L-Threonate and Memory
This brings me to the form of magnesium that I find particularly interesting: magnesium-L-threonate, commonly abbreviated MgT.
Magnesium-L-threonate was developed specifically to increase magnesium concentrations in the central nervous system. Early animal experiments reported improvements in learning, working memory, and both short- and long-term memory.
The evidence has now moved into humans.
A recently published randomized, double-blind, placebo-controlled trial enrolled 100 adults aged 18 to 45. Participants received either 2 grams per day of magnesium-L-threonate or placebo for six weeks.
Compared with placebo, the magnesium-L-threonate group demonstrated greater improvement in the NIH Total Cognition Composite, with particularly notable effects involving working and episodic memory. Reaction time also improved. Not every endpoint improved, including several objective measures of sleep, but the study provides controlled human evidence supporting some of what the earlier animal studies had found.
This is the form of magnesium I personally favor when cognition and brain health are among the objectives.
Your Heart Needs Magnesium
Magnesium is also deeply involved in cardiovascular physiology.
It influences vascular smooth-muscle tone, movement of calcium and potassium across cell membranes, and the electrical activity of the heart. Severe magnesium deficiency can produce abnormal heart rhythms. Magnesium is important enough to cardiac electrophysiology that intravenous magnesium has long-standing medical uses for certain arrhythmias and other acute clinical settings.
But the more interesting question for most of us concerns the effects of chronic, less severe magnesium inadequacy.
A meta-analysis of 38 randomized trials involving 2,709 participants found an average reduction of 2.8 points in the upper (systolic) blood pressure number and 2.1 points in the lower (diastolic) number compared with placebo. In practical terms, a reading of 130/80 would decline, on average, to about 127/78.
Magnesium supplementation appears to lower blood pressure most in people who actually have high blood pressure, particularly those already being treated for hypertension. A 2025 meta-analysis of 38 randomized controlled trials involving 2,709 participants found that among people with hypertension who were already taking blood-pressure medication, magnesium supplementation lowered the upper blood-pressure number by an average of 7.7 points and the lower number by about 3 points compared with placebo. People who were magnesium deficient also experienced larger reductions, while those with normal blood pressure did not experience a statistically significant reduction.
Magnesium is also closely connected to glucose metabolism and insulin signaling. In a pooled analysis of 24 randomized trials involving people with type 2 diabetes, magnesium supplementation was associated with reductions in fasting glucose, HbA1c, and blood pressure.
Magnesium isn’t a miracle cure.
It is something more mundane and perhaps more important: a basic nutrient necessary for the metabolic systems we are asking our bodies to operate every day.
How Much Magnesium Do We Actually Need?
The recommended dietary allowance varies by age and sex. For most adult men, it is approximately 400–420 mg per day, while most adult women require approximately 310–320 mg per day, with somewhat higher requirements during pregnancy.
Those numbers aren’t particularly difficult to reach if someone eats a nutrient-dense whole-food diet.
That “if” is doing a lot of work.
The NIH identifies legumes, nuts, seeds, whole grains, and green leafy vegetables as major dietary sources.
That list looks remarkably similar to the foods that have been displaced by the modern processed diet.
Food First. But Perhaps Not Food Alone.
Magnesium-rich foods should be the foundation. Eat green vegetables. Eat beans and legumes. Eat nuts and seeds. Choose whole grains rather than refined flour. Grow some of your own food if you can. Buy food from farmers who care about their soil. Reduce the amount of highly processed food in your diet.
But there is a problem with stopping the discussion there.
The food isn’t the only thing that changes as we get older. We change too.
Aging alters the gastrointestinal tract and can reduce how efficiently some nutrients are absorbed. Older people may also eat less food, have less varied diets, take medications that interfere with magnesium balance, or develop diseases that increase magnesium losses. Kidney handling of magnesium also changes with age. Proton-pump inhibitors are a particularly important example because long-term use can cause hypomagnesemia in susceptible individuals. Diuretics and several other medications can also alter magnesium status.
This means that the person who was able to maintain adequate magnesium status at 35 may not necessarily do so at 65 or 75 while eating essentially the same diet.
That matters because aging is precisely when many of the biological systems that depend upon magnesium become increasingly important: cardiovascular function, glucose regulation, bone health, muscle function and cognition.
So I don’t think “food first” should automatically mean “food only.”
For many adults, particularly as we age, magnesium supplementation is worth considering alongside a magnesium-rich diet.
The form matters. Magnesium oxide is inexpensive and contains a lot of elemental magnesium, but it is poorly absorbed and commonly causes gastrointestinal effects. Magnesium citrate is better absorbed and useful for people who also benefit from its laxative effect, but for others loose stool isn’t particularly desirable. Magnesium glycinate is widely used and generally well tolerated. Magnesium-L-threonate is considerably more expensive, but is particularly interesting because it was developed to increase magnesium availability in the brain and now has both animal and human evidence concerning cognition.
This is why magnesium-L-threonate is the form I personally favor when brain and cognitive health are part of the objective.
But supplementation shouldn’t become another exercise in the American belief that if some is good, more must be better. The NIH establishes a 350 mg/day upper limit for magnesium from supplements and medications in adults. Importantly, that limit does not include magnesium naturally present in food. It was established primarily because supplemental magnesium can cause diarrhea, nausea, and abdominal cramping. Much higher intakes can become dangerous, especially in people with impaired kidney function, because the kidneys normally eliminate excess magnesium. Magnesium supplements can also interact with several medications.
The objective is adequacy, not excess.
We Keep Rediscovering What Food Used to Provide
Perhaps the most remarkable thing about magnesium is how unremarkable it really is.
It isn’t a newly discovered molecule. It isn’t a pharmaceutical invention. Human beings have required magnesium throughout our evolutionary history.
What changed wasn’t our need for it.
What changed was our food, and as we age, our ability to extract and retain nutrients from that food changes as well.
Modern agriculture bred crops for yield. Industrial food processing refined grains for texture, appearance, and shelf life, stripping the magnesium-rich germ and bran from wheat in the process. The result is an enormous processed-food industry capable of delivering abundant calories while removing many of the micronutrients that once accompanied those calories.
Then we got older.
We ate less. Our gastrointestinal physiology changed. Some of us developed diabetes or gastrointestinal disease. Many began taking medications that affect magnesium absorption or excretion. Yet our physiological requirement for magnesium didn’t disappear.
Nearly half of Americans now consume less magnesium from food than their estimated requirement. A new analysis suggests that more than two-thirds may have serum magnesium concentrations below a proposed threshold for adequate status.
Start with food. Eat the foods in which magnesium naturally occurs. Stop stripping those foods of their nutrients whenever possible.
But particularly as we age, it is also reasonable to consider magnesium supplementation rather than simply assuming that a modern diet will provide everything we need.
We spend enormous amounts of money looking for complicated ways to remain healthy as we age.
Sometimes the answer may begin with something considerably simpler.
Make sure the basic machinery has what it needs to run.
By: JGM/RWM
P.S. A Note About Homesteading for Health
When Robert and I wrote Homesteading for Health, we spent years researching the food supply, agricultural policy, nutrition, and the politics that increasingly determine what ends up on the dinner table. The book documents what has happened to the nutritional quality of food, but it doesn’t stop there. More importantly, it offers concrete, practical ways for individuals and families to take greater control of their food and their health.
There is a reason Homesteading for Health now has more than 100 five-star reviews on Amazon. This isn’t a book about abandoning modern life and moving to a farm. It is about understanding what has changed, then finding realistic ways to eat better, live healthier, and become less dependent on a food system that has increasingly prioritized yield, processing, convenience, and profit over nutrition.
Taking back control of health can begin with something as fundamental as taking back control of food.
And one more thought as the holidays approach: Homesteading for Health makes a great Christmas gift. It is particularly good for anyone who wants to eat better, become more self-sufficient, grow some of their own food, or simply better understand the connection between food and health. It is also a beautiful book, filled with gorgeous illustrations, equally at home on a coffee table or bookshelf, and meant to be picked up and returned to again and again.
References
Malone RW, Malone JG. Homesteading for Health: A Family’s Guide to Self-Sufficiency and Wellness. Skyhorse Publishing; 2026. The article’s discussion of changes in food nutrient density, soil biology, modern wheat, flour refining, and regenerative agriculture draws in part from the research reviewed in this book.
Jiao K, Costello R, Gahche J, Rosanoff A, Wallace TC. Serum magnesium concentrations in the United States: An updated population reference interval in children and adults. J Nutr. 2026;156(6):101539. doi:10.1016/j.tjnut.2026.101539.
National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. NIH. The NIH review includes dietary requirements, food sources, absorption, assessment of magnesium status, supplement forms, medication interactions, and the adult upper limit for supplemental magnesium. It also reports that 48% of Americans consumed less magnesium from food and beverages than their respective EARs in NHANES 2013–2016.
Davis DR, Epp MD, Riordan HD. Changes in USDA food composition data for 43 garden crops, 1950 to 1999. J Am Coll Nutr. 2004;23(6):669–682. doi:10.1080/07315724.2004.10719409.
Fan MS, Zhao FJ, Fairweather-Tait SJ, Poulton PR, Dunham SJ, McGrath SP. Evidence of decreasing mineral density in wheat grain over the last 160 years. J Trace Elem Med Biol. 2008;22(4):315–324. doi:10.1016/j.jtemb.2008.07.002. This is the important Broadbalk study documenting significant declines in magnesium, zinc, iron and copper in wheat grain after the introduction of modern high-yielding cultivars.
Slutsky I, Abumaria N, Wu LJ, et al. Enhancement of learning and memory by elevating brain magnesium. Neuron. 2010;65(2):165–177. doi:10.1016/j.neuron.2009.12.026.
Li W, Yu J, Liu Y, et al. Elevation of brain magnesium prevents synaptic loss and reverses cognitive deficits in Alzheimer’s disease mouse model. Mol Brain. 2014;7:65. doi:10.1186/s13041-014-0065-y.
Chen F, Wang J, Cheng Y, et al. Magnesium and cognitive health in adults: A systematic review and meta-analysis. Adv Nutr. 2024;15(8):100272. doi:10.1016/j.advnut.2024.100272.
Lo K, Liu Q, Madsen T, et al. Relations of magnesium intake to cognitive impairment and dementia among participants in the Women’s Health Initiative Memory Study: a prospective cohort study. BMJ Open. 2019;9:e030052. This study followed 6,473 women aged 65–79 for more than 20 years and examined magnesium intake in relation to incident MCI and probable dementia.
Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Front Nutr. 2026;12:1729164. doi:10.3389/fnut.2025.1729164.
Kass L, Weekes J, Carpenter L. Effect of magnesium supplementation on blood pressure: a meta-analysis. Eur J Clin Nutr. 2012;66(4):411–418. doi:10.1038/ejcn.2012.4.
Zhang X, Li Y, Del Gobbo LC, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension. 2016;68(2):324–333. doi:10.1161/HYPERTENSIONAHA.116.07664.
Touyz RM, et al. Magnesium supplementation and blood pressure: a systematic review and meta-analysis of randomized controlled trials. Hypertension. 2025. doi:10.1161/HYPERTENSIONAHA.125.25129. The analysis included 38 RCTs and 2,709 participants and found mean reductions of 2.81 mmHg systolic and 2.05 mmHg diastolic blood pressure.
Xu L, Li X, Wang X, Xu M. Effects of magnesium supplementation on improving hyperglycemia, hypercholesterolemia, and hypertension in type 2 diabetes: A pooled analysis of 24 randomized controlled trials. Front Nutr. 2023;9:1020327. doi:10.3389/fnut.2022.1020327.
Durlach J, Bac P, Durlach V, Rayssiguier Y, Bara M, Guiet-Bara A. Magnesium status and ageing: an update. Magnes Res. 1998;11(1):25–42. This is useful for the final section because it specifically discusses aging-associated intestinal magnesium hypoabsorption, inadequate intake, urinary losses, diabetes and medication-related depletion.
Always great information to help us age healthy lives. Thanks Dr J.
Now let’s do iodine. More critical and much more deficient.