What foods are good sources of magnesium?
Magnesium is an essential mineral — we have to consume it through our diet, as it’s not produced by the body. The recommended dietary allowance for women is between 310 and 320 milligrams a day, and for men, between 400 and 420 milligrams daily.
Nutrients are best absorbed and utilized by the body when they’re consumed as food. Studies have shown that the way our bodies utilize magnesium is also intertwined with vitamin D, zinc, and calcium, so if we turn to supplements before first considering diet, there’s the potential to inadvertently throw other systems out of balance.
My recommendation is to take a food-first approach, especially incorporating whole foods into the diet, such as:
- Unrefined whole grains
- Nuts such as almonds, cashews, and peanuts
- Leafy greens such as spinach
- Black beans and soybeans
What should people know about magnesium supplements?
Magnesium supplements have good therapeutic potential for many people, but I would recommend speaking to a clinician who has specific training in prescribing supplements in a way that’s safe and evidence based.
There are many forms of magnesium available. What you’re getting with a magnesium supplement is magnesium bound to something else, either an anion or an amino acid, which affects its solubility and bioavailability, or its use in the body.
Overall, the broad evidence for using one specific form of magnesium for one specific condition — such as one type for anxiety or another for muscle health — is lacking. In general, I recommend choosing a form that’s more readily absorbed by the body.
Magnesium oxide is among the most commonly used forms due to its low cost and high elemental magnesium content, but this form is also less soluble and bioavailable compared to other magnesium compounds. You’ll see it in laxative preparations because it’s not very well absorbed by the digestive tract and cleans out the bowels.
Magnesium citrate and magnesium glycinate are thought to be more bioavailable and absorbable forms of magnesium, although evidence to support this is mixed. I will often prescribe magnesium glycinate to address issues such as anxiety or headaches.
If somebody wants to start taking magnesium, I generally start with a lower dose, and I’ll often prescribe it for around bedtime, because it can be helpful for relaxation and sleep. If anything changes with their medications or supplement regimen, adjustments may be needed.
Looking at the bigger picture, especially considering the way that magnesium interacts with other nutrients in the body, it’s important to make sure that we’re first optimizing our lifestyle when we’re considering taking a supplement for things like stress, anxiety, or high blood pressure. Take a look at things like your nutrition, sleep, relationships, and daily physical activity before going straight to supplements to address symptoms.
A supplement should not be taken long term without reassessing why you’re using it.
Are there any side effects of magnesium supplements? Who should not take it?
The most common side effect of taking too much magnesium is loose stools or diarrhea. It’s a sign that you either need to choose a different formulation or decrease your dosage.
People who have kidney disease are at high risk of developing adverse effects from magnesium supplements because their bodies will not excrete it well.
Individuals who have myasthenia gravis, a chronic autoimmune disorder, should not take magnesium, nor should people taking angiotensin-converting enzyme (ACE) inhibitors, which are medications commonly used to treat high blood pressure and heart problems. A variety of medications can potentially interact with magnesium, so it is best to speak with a physician before starting a magnesium supplement.