The best way to get magnesium is through a combination of magnesium-rich foods and, if needed, a well-absorbed supplement form taken with food. Your body absorbs roughly 30% to 40% of the magnesium you eat, and certain supplement forms match or exceed that rate, while others barely register. The details matter more than most people realize.
Food Sources With the Most Magnesium
Seeds, nuts, and leafy greens are your richest options. Pumpkin seeds deliver about 156 mg per ounce, making them one of the most concentrated food sources available. Almonds provide around 80 mg per ounce, and cashews about 74 mg. A half cup of cooked spinach has roughly 78 mg, and a half cup of black beans offers around 60 mg. Whole grains like brown rice and quinoa, avocados, and dark chocolate (70% cacao or higher) all contribute meaningful amounts too.
Most adults need between 310 and 420 mg per day depending on age and sex, with men on the higher end. A diet built around whole grains, nuts, seeds, and vegetables can realistically hit that target. But many people fall short, partly because processed and refined foods lose most of their magnesium during manufacturing.
Not All Greens Are Equal
Here’s something worth knowing: the vegetable you choose changes how much magnesium you actually absorb. A study in the British Journal of Nutrition compared magnesium absorption from spinach and kale served with the same meal. Participants absorbed only 26.7% of the magnesium from the spinach meal, compared to 36.5% from the kale meal. The difference comes down to oxalic acid. Spinach is loaded with oxalates, which bind to magnesium in your gut and prevent absorption. Kale has almost none.
This doesn’t mean spinach is a bad food. It just means that if you’re eating greens specifically for magnesium, low-oxalate options like kale, collard greens, and Swiss chard give you more bang for your effort. The same logic applies to other high-oxalate foods like beet greens and rhubarb.
Which Supplement Forms Actually Work
If your diet isn’t covering your needs, supplements can fill the gap. But the form you choose makes an enormous difference. Magnesium citrate is one of the best-absorbed oral forms, often used as the reference standard in absorption studies. Magnesium glycinate (also called bisglycinate) absorbs at roughly 80% the rate of citrate and tends to be gentler on the stomach, making it a popular choice for people prone to digestive issues. Magnesium malate absorbs at a rate similar to citrate.
Magnesium oxide, on the other hand, absorbs at roughly 4%. It’s the cheapest form and the most common in drugstore supplements, which is unfortunate because you’re getting very little usable magnesium per pill. If you’ve tried magnesium supplements before and felt no difference, there’s a good chance you were taking oxide.
Magnesium chloride and magnesium lactate also fall into the well-absorbed category. The general rule: forms that dissolve easily in liquid tend to absorb better in your gut.
Take It With Food
Timing matters less than people think, but one habit consistently improves absorption: taking your supplement with a meal. One study found that magnesium absorption from mineral water jumped from 45.7% to 52.3% simply by drinking it with food instead of on an empty stomach. Food slows the transit of material through your digestive tract, giving your intestines more time to pull magnesium into your bloodstream.
Taking magnesium with food also reduces the most common side effect, which is loose stools or stomach cramping. This is especially true for citrate, which can have a mild laxative effect at higher doses. If you’re splitting your dose across two meals, that’s even better for both absorption and tolerance.
As for time of day, there’s no strong evidence that morning or evening dosing changes how much you absorb. Some people prefer taking magnesium in the evening because of its mild calming effect, but consistency matters more than the clock.
Vitamin D and Magnesium Work Together
Magnesium is a cofactor for the enzymes that activate vitamin D in your body. Without enough magnesium, your body can’t convert vitamin D into its usable form efficiently. This also works in the other direction: taking vitamin D supplements increases your body’s demand for magnesium. If you’re supplementing with vitamin D (as many people are, especially in northern climates), your magnesium needs may be higher than the standard recommendation. Research suggests that people with adequate magnesium levels see better improvements in their vitamin D status.
Topical Magnesium Is Mostly Marketing
Magnesium sprays, lotions, and Epsom salt baths are widely promoted as an alternative way to raise your levels through the skin. The clinical evidence for this is weak. A study from the University of North Carolina tested transdermal magnesium chloride (both oil and balm) and found it had minimal effect on muscle recovery or soreness, despite applying an average of roughly 1,190 mg total across the study period. The researchers concluded the transdermal route simply didn’t deliver enough magnesium to make a measurable difference.
An Epsom salt bath may feel relaxing, and that’s a perfectly fine reason to take one. But if your goal is to raise your magnesium levels, oral sources are far more reliable.
A Practical Approach
Start with food. A handful of pumpkin seeds on your oatmeal, a serving of black beans at lunch, and a side of kale or collard greens at dinner can get you most of the way to your daily target. If you’re still falling short, or if you have higher needs due to exercise, stress, or vitamin D supplementation, add a well-absorbed supplement form like citrate, glycinate, or malate. Take it with a meal, and keep your supplemental dose at or below 350 mg per day, which is the tolerable upper intake level set by the NIH for magnesium from supplements specifically. Magnesium from food carries no upper limit because your kidneys handle the excess easily, but concentrated supplement doses can cause diarrhea and cramping before any serious risk emerges.