- Magnesium is involved in over 300 biochemical processes in the body, including several that directly support heart muscle function, blood pressure regulation, and heart rhythm.
- Low magnesium levels have been associated with higher rates of atrial fibrillation, coronary artery disease, stroke, and type 2 diabetes.
- Around 1 in 3 adults may not meet their daily magnesium requirement through diet, rising to around half of adults over 70.
- Most people can get enough magnesium from food, pumpkin seeds, nuts, leafy greens, legumes, and whole grains are all excellent sources.
- Magnesium supplements are generally safe in normal doses but can cause side effects in excess and interact with some medications, always discuss with your doctor before supplementing, particularly if you take diuretics, proton pump inhibitors, or medications for heart failure.
Magnesium doesn’t get the headlines that vitamin D or omega-3 fatty acids attract, but it probably should. It is one of the most abundant minerals in the body, involved in more than 300 biochemical processes, and plays a genuinely important role in keeping the heart functioning well. Yet surveys consistently show that a significant proportion of adults fall short of their recommended daily intake, often without knowing it.
This article looks at what magnesium does for the heart, what low levels can mean for cardiovascular risk, where to find it in food, and when supplementation might be worth discussing with a doctor.
How Much Magnesium Do We Need?
Magnesium requirements increase during adolescence and remain elevated through adulthood. As a general guide, adult men need around 400mg per day and adult women around 300mg per day with requirements increasing slightly with age. Most people with a varied diet that includes nuts, seeds, whole grains, and leafy greens will come reasonably close to this without tracking it carefully.
That said, surveys suggest around one in three adults may not consistently meet their daily requirement, and among adults over 70, that proportion rises to roughly half. Magnesium is lost through sweat and urine, and certain medical conditions and medications can further deplete it.
What Magnesium Does for the Heart
Heart Rhythm
One of the most clinically significant roles of magnesium in cardiovascular health is its influence on heart rhythm. Magnesium helps regulate the electrical signals that coordinate the heartbeat, and low levels have been associated with an increased risk of atrial fibrillation the most common heart rhythm disorder, in which the upper chambers of the heart beat irregularly.
A sub-study of the long-running Framingham Heart Study found that people with low-normal blood magnesium levels had a meaningfully higher risk of developing atrial fibrillation compared to those with higher levels within the normal range, even after accounting for other factors. Magnesium has also been studied in the context of atrial fibrillation following cardiac surgery, where some research suggests it may reduce the risk of this common postoperative complication.
Blood Vessel Health
Magnesium plays an important role in maintaining the health of the endothelium, the thin inner lining of blood vessels that regulates blood flow, blood pressure, and the body’s response to injury and inflammation. A healthy endothelium is central to preventing atherosclerosis, the gradual build-up of plaques inside arterial walls that is the underlying cause of most heart attacks and strokes.
Studies have shown that magnesium supplementation in people with stable coronary artery disease may improve exercise tolerance and blood flow compared to placebo, an effect attributed in part to improved endothelial function.
Anti-Inflammatory Effects
Chronic low-grade inflammation is increasingly recognised as a key driver of cardiovascular disease. Magnesium has demonstrated anti-inflammatory properties in research, and adequate magnesium levels appear to help keep inflammatory markers lower. This is relevant not just for heart disease but also for the risk of type 2 diabetes, itself a significant cardiovascular risk factor.
Heart Muscle Function
Magnesium helps regulate the balance between heart muscle contraction and relaxation, a function that becomes particularly important in people at risk of heart failure. It also supports the body’s ability to regulate blood pressure, in part through its effects on blood vessel tone and the balance between sodium and potassium at the cellular level.
Magnesium is one of those nutrients where the evidence consistently points in the same direction, adequate levels appear to support heart rhythm, blood vessel health, and inflammation control simultaneously. It is not a supplement to chase at high doses, but it is one worth making sure you are getting enough of through food.
— Dr Angus Gill
Where to Get Magnesium Through Food
The good news is that magnesium is widely available in everyday foods, and reaching adequate levels through diet is entirely achievable for most people with a few modest adjustments. The table below highlights some of the best sources.
| Food | Serving | Magnesium | % Daily Intake* |
|---|---|---|---|
| Pumpkin seeds, roasted | 30g | 156mg | 37% |
| Chia seeds | 30g | 111mg | 26% |
| Almonds, dry roasted | 30g | 80mg | 19% |
| Spinach, boiled | ½ cup | 78mg | 19% |
| Cashews, dry roasted | 30g | 74mg | 18% |
| Edamame, cooked | ½ cup | 50mg | 12% |
| Brown rice, cooked | ½ cup | 42mg | 10% |
| Plain low-fat yogurt | 225g | 42mg | 10% |
| Oatmeal (instant) | 1 packet | 36mg | 9% |
| Kidney beans, canned | ½ cup | 35mg | 8% |
| Banana | 1 medium | 32mg | 8% |
| Salmon, cooked | 100g | 30mg | 7% |
| Wholegrain bread | 1 slice | 23mg | 5% |
| Avocado | ½ cup | 22mg | 5% |
*Based on a daily intake of 420mg. Source: NIH Office of Dietary Supplements.
A handful of almonds as a daily snack, a serve of spinach with dinner, brown rice instead of white, and a bowl of oats for breakfast can collectively make a meaningful contribution to daily magnesium intake without any dramatic dietary change. The Mediterranean diet, rich in nuts, legumes, whole grains, and leafy vegetables, is naturally high in magnesium, which may partly explain some of its cardiovascular benefits.
What About Supplements?
For most people with a reasonable diet, magnesium supplements are not necessary. Food sources are preferable, they come with fiber, vitamins, and other nutrients that supplements don’t replicate.
That said, some people may benefit from supplementation, particularly older adults, those with conditions that deplete magnesium (such as type 2 diabetes or chronic gastrointestinal conditions), and people on certain medications. Magnesium supplements are available in several forms, magnesium glycinate and magnesium citrate tend to be better absorbed and gentler on the digestive system than magnesium oxide.
Some commonly prescribed medications can lower magnesium levels or interfere with its absorption. These include:
- Diuretics (water tablets), particularly loop diuretics such as furosemide, which increase magnesium excretion through the kidneys
- Proton pump inhibitors (PPIs) medications used for acid reflux such as omeprazole or pantoprazole, which can reduce magnesium absorption with long-term use
- Some antibiotics and diabetes medications can also affect magnesium balance
A Few Simple Ways to Get More Magnesium
- Swap white rice for brown a small change that doubles the magnesium content per serving.
- Keep a small bag of mixed nuts at your desk almonds and cashews are among the most magnesium-dense snack options available.
- Add pumpkin seeds to oats, salads, or yogurt 30g provides more than a third of the daily requirement in one go.
- Include leafy greens regularly spinach, silverbeet, and kale are all good sources and work well in soups, stir-fries, and salads.
- Choose wholegrain bread over white, better for fiber and magnesium simultaneously.
- Eat legumes a couple of times a week kidney beans, edamame, and lentils all contribute meaningfully to daily intake.
Conclusion
Magnesium is one of those nutrients that works quietly in the background, supporting heart rhythm, blood vessel function, inflammation control, and blood pressure regulation simultaneously. It is not a supplement to chase at high doses or treat as a cardiovascular cure, but it is worth making sure you are getting enough of it through food.
For most people that means leaning into nuts, seeds, whole grains, and leafy greens as regular parts of the diet, changes that tend to improve overall dietary quality well beyond magnesium alone. If you have specific concerns about your magnesium levels, particularly if you are on medications that affect magnesium balance, a conversation with your doctor is a straightforward next step.
