镁的 12 个好处与副作用：营养师说，先看证据再看剂量

In the expansive world of vitamins and nutrients, you’ve probably heard of magnesium, but you may be fuzzy on the details. Because many Americans don’t get enough magnesium in their diet, it is a micronutrient worth paying attention to.

Here’s the thing: Magnesium supports more than 300 reactions in your body, says Sonya Angelone, RD, a spokeswoman for the Academy of Nutrition and Dietetics. That includes things like your body’s ability to break down protein, help your muscles function, and produce energy. “Magnesium also helps transport calcium and potassium across cell membranes,” Angelone says.

Magnesium shows up in a slew of foods (more on those in a sec), but you can also get more of it from taking a supplement. So, what benefits of magnesium do you need to know about? Are there any risks to taking a magnesium supplement? Here’s the deal.

Meet the experts: Sonya Angelone, RD, is a spokeswoman for the Academy of Nutrition and Dietetics. Jessica Cording, RD, is a dietitian and author of The Little Book of Game-Changers. Scott Keatley, RD, is co-owner of Keatley Medical Nutrition Therapy.

What Is Magnesium?

“Magnesium is an essential micronutrient, meaning that we have to get relatively small amounts of it from our diet or via supplementation,” explains Scott Keatley, RD, co-owner of Keatley Medical Nutrition Therapy. Magnesium is a “co-factor” in many systems in your body, “which means without magnesium things just won't function properly,” Keatley reiterates.

How Much Magnesium Do You Need?

Most adult women should get 310 to 360 milligrams of magnesium a day, depending on age and whether you’re pregnant or breastfeeding. If you get less than that, your body may not function as efficiently as it should.

Unfortunately, an analysis of data from the National Health and Nutrition Examination Survey (NHANES) found that 48 percent of Americans of all ages have less magnesium than they should.

Benefits of Magnesium

1. It can help with your workouts.

Magnesium is “crucial for proper muscle contractions,” Angelone says, noting that it helps prevent muscle cramps and has even been linked with helping people work out more. A 2024 review found that adequate magnesium intake benefits muscle mass, power, and performance. Moreover, this micronutrient may improve muscle stem cells and counteract muscle atrophy.

2. It plays a role in heart health.

“Magnesium helps maintain a regular heart rhythm,” Angelone says. “It has also been found to help with atrial fibrillation and high blood pressure since it is a smooth muscle relaxant.”

In fact, magnesium supplements positively affected risk factors for heart disease, including LDL (bad) cholesterol, HDL (good) cholesterol, and blood pressure levels—especially in people who were deficient in magnesium, according to a 2017 scientific review.

3. It may help reduce your risk of developing depression.

“Magnesium helps block certain receptors in the brain, which can lead to less excitement and damage to the cell,” Angelone says. Low magnesium intake was linked with depression in study participants who were under 65, one 2015 data analysis of more than 8,800 people found. In fact, those with the lowest levels of magnesium intake had a 22 percent greater risk of depression.

Still, it’s hard to say that low magnesium levels actually cause depression. “What is more likely is that individuals with depression have eating patterns that are not conducive to maintaining food magnesium status and that magnesium supplementation or increased intake of magnesium helps get everything back running to 100 percent,” Keatley explains. “But the underlying depression has to be dealt with.” So make sure to work with a mental health professional if you are experiencing symptoms of depression.

4. It could help ease anxiety symptoms.

People who had higher levels of magnesium had a lower risk of anxiety and depression, one study of nearly 3,200 people found. Magnesium deficiency “is associated with high stress levels which may contribute to anxiety,” Angelone says. “Magnesium may also help lower cortisol and increase GABA (gamma-aminobutyric acid), which, in turn, can help lower anxiety,” she adds.

5. It helps support healthy blood sugar levels.

Bear with us here for a sec: Magnesium competes with calcium in your body, and high levels of calcium are linked with a decrease in production of insulin, which helps move glucose (aka sugar) into your cells where it’s used for energy. That “means more sugar stays in the blood, causing damage,” Keatley says.

On the flip side, magnesium can help your body use insulin and keep those levels in balance, Angelone says. Higher magnesium levels have been linked with a lower risk of developing type 2 diabetes, which is when your body can’t make or use insulin properly, per 2017 research in Diabetes Care.

6. It may play a part in tamping down inflammation.

Bodily inflammation has been linked with everything from pain to the development of serious health conditions like diabetes and cancer. As a result, controlling the inflammation can be beneficial.

But magnesium’s role in tamping down inflammation is indirect. “Magnesium is a major player in glutathione, the body's master antioxidant, but magnesium by itself does not have any anti-inflammatory benefits,” Keatley says. Magnesium also impacts the production of the active form of vitamin D in the body, “which is related to a healthy immune system,” Angelone says.

7. It could help with PMS.

PMS can cause intense symptoms like pain and cramping, and magnesium may help. “The role of magnesium as a smooth muscle relaxant may help alleviate cramps,” Angelone says. Research backs this up, showing it may help with cramps, menstrual migraine, and other symptoms, a 2017 scientific literature review determined.

8. It may help you sleep.

“Magnesium can help you relax and sleep longer,” Angelone says. “It can also help regulate melatonin secretion, which helps a person fall asleep.” She also points out that magnesium helps maintain healthy levels of GABA, a neurotransmitter that promotes sleep.

Worth noting: People who took magnesium supplements were able to fall asleep about 17 minutes faster in a 2021 scientific review of 151 older adults with insomnia.

9. It may lower your risk of headaches.

Increasing your magnesium intake may help lower the number of headaches you get, Keatley says. In fact, a 2021 randomized controlled trial found magnesium oxide as effective as the medication valproate sodium at preventing migraine headaches. Why? The link is still being explored, but some theories exist. “Magnesium plays a role in serotonin production as well as GABA, dopamine, and norepinephrine—all of which can decrease the physical effects of stress,” Keatley says. Stress is a risk factor for migraine headaches and, in theory, having more magnesium in your life could help reduce this.

Another theory? Magnesium helps your muscles chill out. “Magnesium is a smooth muscle relaxant, so it can be helpful in reducing tension headaches and migraines,” Angelone says.

10. It supports bone health.

Magnesium actually does a lot for your bones. “The majority of magnesium is stored in the bones and works closely with calcium for bone health,” Angelone says. “Magnesium has a role in the structure of bone, influences bone-building cells, and helps lower inflammation that can damage bone and lead to bone breakdown.”

Magnesium deficiency has been linked to the development of osteoporosis (a condition characterized by reduced bone mineral density), according to a 2024 review published in Cureus.

11. It can support digestive functioning.

Too much magnesium can give you diarrhea, Keatley points out. On the flip side, it can also help keep things moving if you tend to get stopped up. Again, magnesium is a smooth muscle relaxant, and that can help with the muscular contractions that push stool through the gut, Angelone adds.

“Certain forms of magnesium supplements also pull water into the gut, which can be helpful for bowel motility.” If you struggle with constipation, it’s worth asking your doctor about increasing your magnesium intake. “Magnesium acts basically as a stool softener and can make stool easier to pass,” Angelone says.

12. It may help with bruxism.

The development of bruxism (grinding teeth) may be linked to lower levels of magnesium, according to a 2023 review. “There is a connection between reduced feelings of stress with enough magnesium, and people who hold stress tend to hold muscle tension,” says Jessica Cording, RD, a dietitian and author of The Little Book of Game-Changers. If you’re dealing with bruxism, talk to your dentist about next steps. While you’re at it, you can ask if magnesium may help—but it’s likely to be more of a supportive therapy vs. the ~only~ thing you do.

Main Food Sources of Magnesium

Magnesium is largely found in plant and animal foods, according to the National Institutes of Health (NIH). Some food sources include:

• Pumpkin seeds (156 milligrams; 37 percent of your daily value per ounce)
• Chia seeds (111 milligrams; 26 percent of your daily value per ounce)
• Almonds (80 milligrams; 19 percent of your daily value per ounce)
• Spinach (78 milligrams; 19 percent of your daily value per ½ cup boiled)
• Black beans (60 milligrams; 14 percent of your daily value per ½ cup)
• Peanut butter (49 milligrams; 12 percent of your daily value per 2 tablespoons)
• Bananas (32 milligrams; 8 percent of your daily value per ounce)
• Salmon (26 milligrams; 6 percent of your daily value per 3 ounces)
• Milk (24 milligrams; 6 percent of your daily value per 1 cup)

You can also take a magnesium supplement. It’s usually prescribed for people with conditions like Celiac disease, type 2 diabetes, and alcoholism, Angelone says. “Excess stress and caffeine can also deplete magnesium stores in the body,” she adds. Endurance athletes can also struggle with low magnesium levels, Keatley says. Always talk to your healthcare provider before taking any new supplements.

How to Know If You're Getting Enough Magnesium

Symptoms of low magnesium can vary depending on how long you’ve been deficient, Angelone says.

Early signs may include:

• Loss of appetite
• Nausea
• Vomiting
• Fatigue
• Weakness

Magnesium deficiency that hasn’t been treated can include:

• Numbness
• Muscles cramps
• Seizures
• Abnormal heart rhythm
• Low calcium
• Low potassium

Magnesium Side Effects and Risks

Magnesium supplements can cause a few side effects. Angelone says to watch out for:

• Watery poop or diarrhea
• Upset stomach

If you have way too much magnesium, you could struggle with low blood pressure, an irregular heartbeat, and even a coma, Angelone says. “However, this is rare,” she adds.

Magnesium may also interact with some medications. According to the NIH, those include:

• Bisphosphonates. Magnesium can lower your body’s absorption of bisphosphonates. If you take these medications, space them at least 2 hours apart from any magnesium supplements.
• Certain antibiotics. Magnesium can form complexes with antibiotics like doxycycline, ciprofloxacin, and levofloxacin. Take your antibiotics at least two hours before or four to six hours after your magnesium supplement.
• Diuretics. Loop diuretics like furosemide and bumetanide, along with thiazide diuretics like hydrochlorothiazide and ethacrynic acid, can cause you to lose more magnesium in your urine.
• Proton pump inhibitors (PPIs). These medications can cause a magnesium deficiency when taken long-term.

If you’re concerned about your magnesium levels, talk to your doctor. They may want you to get bloodwork to check your magnesium levels and take it from there.