The Vegetable To Avoid Eating Alongside Your Magnesium Supplements

Taking magnesium supplements can improve your heart health, lower your blood sugar, reduce the number of migraines you experience, and provide you with a host of other benefits. But there's one roadblock you have to overcome first: Magnesium isn't always efficiently absorbed by your body.

(Here's everything you need to know about magnesium.)

When you eat foods that are rich in dietary magnesium, your system may only absorb 30% to 40% of their magnesium content (per the National Institutes of Health). Even if you augment your diet with magnesium supplements, you have to consider that some forms of magnesium are naturally much less bioavailable than others.

With that in mind, you'll want to take precautionary measures to reduce all the barriers to magnesium absorption, including not taking your magnesium supplements with foods that can interfere with the mineral's bioavailability. One of those foods is spinach.

While typically a healthy choice and a rather popular vegetable, spinach isn't your magnesium supplement's BFF for a couple of reasons. The first has to do with the presence of compounds called oxalates in spinach.

You may have heard of oxalates if you've ever had a kidney stone. When your urine has an abundance of oxalates, you may be at higher risk of developing a specific type of kidney stone. (Here's what you can do to decrease your risk of kidney stones.) Avoiding high-oxalate foods could help protect your kidneys. However, oxalates don't just raise your likelihood of kidney stones; they can also bind with magnesium, making it more difficult for your body to access the mineral.

Interestingly, the reverse of this phenomenon can be helpful for people who want to lower their oxalate levels; since magnesium binds with oxalate, it helps keep oxalates from building up in the body. Keep in mind, though, that the magnesium is ultimately flushed away along with the oxalates.

The second problem with pairing magnesium with spinach involves calcium, which is present in many vegetables. A cup of spinach contains 245 milligrams of calcium, which is about the same amount that you'd find in 4 ounces of plain yogurt.

Consuming high amounts of calcium can interfere with magnesium bioavailability as well. When your body encounters both minerals at once, it has to choose which one to use right away, and calcium is often the preferred nutrient. Consequently, if you take your magnesium supplement with a calcium-rich food or drink, you might get less magnesium than you anticipate.

This doesn't mean that you can't have spinach if you're taking magnesium supplements. You just need to stagger your consumption of spinach with your consumption of magnesium. Additionally, you may want to occasionally eat more fermented forms of spinach: A 2023 study in Microorganisms showed that fermented spinach contained fewer oxalates than fresh spinach.