Nutrition A to Z · No. 2
Welcome back to Nutrition A to Z! This is the series where we slow down and get to know one nutrient at a time. What it is, what it does for you, where to find it, and my very favorite part, which nutrients it teams up with.
Because that is the heart of this whole series: nutrients are not solo artists. They work in teams. Once you can see the team, the way your body works starts to feel a lot less mysterious and a lot more like a beautifully organized group project.
And magnesium had to come second. If you read the first post, you already know why. Vitamin D cannot become its active, useful self without magnesium standing by. So here we are in October, my favorite season of the year, the season when everyone is thinking about vitamin D, and I want to make sure the mineral that turns that vitamin on gets its own spotlight.
The quick version
Magnesium is a cofactor in more than 300 enzyme systems, which is a fancy way of saying it helps hundreds of reactions actually happen.
It has a hand in muscle and nerve function, blood sugar, blood pressure, and building protein, bone and DNA.
National survey data suggests about 48 percent of Americans take in less magnesium from food and beverages than they need.
It is the activator of the nutrient world. Vitamin D, potassium and calcium all work better when magnesium is on board.
What it is
Magnesium is a mineral, and it is also an electrolyte, which means it carries a small electrical charge and helps your cells communicate. Your body cannot make it. Every bit of it comes from what you eat, drink or supplement.
Magnesium never travels alone. It is always attached to something. In plants, a magnesium atom sits right in the center of every chlorophyll molecule, which is the reason dark leafy greens are such a lovely source. In a supplement, magnesium is bound to a carrier, and that carrier is the whole reason there are so many different kinds on the shelf. More on that in a minute.
Once magnesium is in you, your body is thrifty with it. Roughly half to sixty percent of the magnesium in your body is tucked into your bones, where it serves as both structure and savings account. Most of the rest sits inside your soft tissues and cells, doing the daily work. Only about one percent of your total magnesium is floating in your blood at any given time.
And here is the part I find genuinely wonderful. Magnesium does not run one system. It shows up as a helper for hundreds of different enzymes, which means it has a hand in almost everything your body does in a day, from making energy to calming a muscle down.
Magnesium does not do one job. It holds the keys to more than three hundred of them.
What it does
Helps your muscles let go. This is my favorite way to explain magnesium. Calcium tells a muscle to contract. Magnesium tells it to release. They are the gas pedal and the brake pedal, and you need both working for a smooth ride. When magnesium runs short, muscles can feel tight, twitchy and slow to unwind.
Steadies your nervous system. Magnesium is involved in nerve signaling and in how your body handles the stress response. For busy women who are running a household, a job and everyone's calendar, that connection is not a small thing. Stress and magnesium have a two way relationship: stress appears to use magnesium up faster, and running low can make everything feel louder.
Supports restful sleep. That same calming, muscle-releasing, nerve-steadying work is exactly why magnesium comes up so often in sleep conversations. It is one of the first things I look at with a client who tells me she is exhausted and still lying awake at eleven o'clock.
Helps regulate blood sugar and blood pressure. The National Institutes of Health names both directly. Magnesium is part of how your body manages blood sugar and how it regulates blood pressure, two things that quietly shape how you feel every single afternoon.
Builds and protects bone. With most of your magnesium stored right in your skeleton, it is a structural mineral, not just a functional one. This matters enormously for women in their forties and fifties. As estrogen shifts through perimenopause and menopause, bone becomes something we have to actively support rather than assume, and magnesium is part of that support alongside calcium, vitamin D and vitamin K2.
Plays a role in your hormone picture. Magnesium influences the levels of both parathyroid hormone and the active form of vitamin D, which are two of the main characters in how your body manages calcium. I find that fascinating. Magnesium is not a hormone itself, but it is standing in the room while hormones do their work.
Supports a balanced immune system, indirectly but importantly. I want to be careful and honest here. Magnesium is not an immune supplement in the way vitamin D is. But vitamin D cannot reach its active form without magnesium, and vitamin D is central to immune balance. So for the women I work with on autoimmune wellness, magnesium is part of the conversation because of the door it opens, not because of a claim I am making about magnesium itself.
Where you get it
Food
Food first, always. That is where I start with every client, and magnesium is a genuinely fun one to eat your way toward, because the foods are delicious. Here are some of the best sources, using numbers from the National Institutes of Health.
Pumpkin seeds, roasted (1 ounce): 156 mg
Chia seeds (1 ounce): 111 mg
Almonds, dry roasted (1 ounce): 80 mg
Spinach, boiled (1/2 cup): 78 mg
Cashews, dry roasted (1 ounce): 74 mg
Peanuts, oil roasted (1/4 cup): 63 mg
Black beans, cooked (1/2 cup): 60 mg
Edamame, shelled, cooked (1/2 cup): 50 mg
Peanut butter, smooth (2 tablespoons): 49 mg
Potato, baked with skin (3.5 ounces): 43 mg
Brown rice, cooked (1/2 cup): 42 mg
Yogurt, plain, low fat (8 ounces): 42 mg
Kidney beans, canned (1/2 cup): 35 mg
Banana (1 medium): 32 mg
Salmon, cooked (3 ounces): 26 mg
Avocado, cubed (1/2 cup): 22 mg
Look at that list and you can see the pattern right away. Seeds, nuts, beans, dark greens and whole grains. Plants that are green or plants that store energy. If you want one easy win this week, it is pumpkin seeds. They are the runaway champion, they keep forever in the pantry, and they are wonderful on a salad or a bowl of soup.
Supplements
Now let me be real with you, the way I always try to be. Eating well is the foundation, and it is not always enough on its own. National survey data suggests roughly half of Americans do not take in enough magnesium from food and beverages. That is not a moral failing. It is the world we eat in.
Part of it is refining. When a whole grain is processed into white flour, the germ and bran come off, and a great deal of the magnesium goes with them. Part of it is that beautiful green vegetables and beans are simply not on most plates every single day. Add a demanding schedule, a lot of stress and a body in hormonal transition, and the gap gets real.
This is exactly where I love a good supplement. Not as a substitute for real food, but as the honest, practical way to fill in what modern eating leaves behind. When I look at a magnesium supplement, I look for three things:
A well absorbed form, which usually means magnesium bound to an amino acid or an organic acid rather than the cheapest option on the shelf.
A form that matches the goal, because the different types really do behave differently, and choosing on purpose beats choosing at random.
Quality you can trust, ideally from a company that is open about its sourcing and testing and does not hide its ingredients behind a blend.
How to take it. Magnesium is generally easy to live with. It does not need fat the way vitamin D does, and many people find it sits best with food. If you are taking it for rest and muscle release, evening tends to be the natural time. If you are taking it for daytime energy, morning makes more sense. Split across the day is often gentler on the stomach than all at once. And if a form ever loosens your stool, that is your body's very clear signal to adjust the amount or switch forms, which is a great conversation to have with your provider.
The different forms, in plain language
This is the part that confuses everyone in the supplement aisle, so let me make it simple. The word after "magnesium" tells you what the magnesium is attached to, and that carrier changes how well it absorbs and what it tends to be used for.
Magnesium glycinate. Bound to glycine, a calming amino acid. Well absorbed and famously gentle on the digestive system. This is the form people most often reach for when sleep, stress and muscle tension are the goal.
Magnesium citrate. Bound to citric acid. Well absorbed and widely available. It also draws water into the intestine, so it has a reputation for helping things move along. Lovely if that is what you want, less lovely if it is not.
Magnesium oxide. Carries a lot of magnesium by weight but absorbs poorly compared with forms like citrate. It is inexpensive, which is why it fills so many bargain bottles, and it is more often used for occasional constipation or heartburn than for actually raising magnesium status.
Magnesium malate. Bound to malic acid, which is part of how your cells produce energy. This is the one people tend to choose for daytime, for stamina and for muscle comfort.
Magnesium L-threonate. The newest of the group, studied for its ability to reach brain tissue. It is the form associated with focus, memory and mental clarity, and it is usually the priciest.
There is no single best one. There is a best one for what you are trying to support, and that is a wonderful thing to sort out with your provider or with me.
A warm heads up on timing. Magnesium can bind to certain medications in your gut and keep them from absorbing properly. That includes oral bisphosphonates for bone density and antibiotics in the tetracycline and quinolone families. The fix is usually simple spacing, taking them at least a couple of hours apart, but please let your pharmacist or provider tell you what is right for your prescriptions.
Synergy partners: magnesium's dream team
Here we are at my favorite section. If vitamin D was the messenger, magnesium is the activator. It is the one that turns the key so the rest of the team can get to work. Which means magnesium does not just have partners, it makes partners possible.
The team: Magnesium, Vitamin D, Vitamin B6, Potassium, Calcium.
Vitamin D, the one magnesium turns on
Picture a beautiful car sitting in the driveway with a full tank. Vitamin D is the car. Magnesium is the key in the ignition. Without the key, nothing happens, no matter how full that tank is.
The enzymes that convert vitamin D into its active form depend on magnesium, and magnesium influences the level of active vitamin D your body ends up with. A 2018 review in the Journal of the American Osteopathic Association made this case clearly and it changed how a lot of us talk about vitamin D. If someone is supplementing with D and not feeling any different, magnesium is one of the first things worth looking at.
Where to find the pair together: salmon brings both. So does a plate with dark leafy greens, seeds and a couple of eggs.
Vitamin B6, the doorman
Magnesium has to get inside your cells to do its job, and B6 appears to help it get through the door. Think of B6 as the doorman who recognizes magnesium and waves it in.
This partnership is the reason you see so many magnesium supplements formulated with B6 right alongside it, and the reason the two show up together in research on stress. It is a small detail that makes a real difference.
Where to find B6: chickpeas, salmon, tuna, poultry, potatoes and bananas. Notice that bananas and potatoes are on the magnesium list too. Nature is efficient like that.
Potassium, the one magnesium keeps in place
Potassium belongs inside your cells, and magnesium is the gatekeeper who keeps it there. When magnesium runs low, potassium leaks out and slips away in your urine, and it becomes very difficult to bring potassium levels back up until magnesium is sorted out first. Clinicians have known this for decades, and it is one of the clearest examples of teamwork in all of nutrition.
Where to find potassium: potatoes with the skin, beans, leafy greens, avocado, bananas, oranges and yogurt. Again, look how much of that list overlaps with magnesium. Eat the whole plant food and you get the whole team.
Calcium, the other pedal
Back to the gas and the brake. Calcium drives contraction, magnesium allows release. Your heart, your muscles and your nerves all need that rhythm of tension and letting go, and both minerals have to be present for it to work.
They also compete a little for absorption, which is the honest part of this partnership. They travel some of the same routes into your body, so taking very large amounts of one at the same moment as the other is not the most graceful approach. Spreading them out across the day is kinder to both.
Where to find calcium: yogurt, sardines with the bones, leafy greens, almonds and fortified foods. Almonds and greens are pulling double duty on this team, which I love.
Who tends to run low
Honestly, a lot of us. But you are more likely to need extra attention here if you:
Eat mostly refined grains and packaged foods, where much of the magnesium has been processed out
Live under sustained stress, since your body appears to burn through magnesium faster when it is under pressure
Have a digestive condition that affects absorption, like Crohn's disease or celiac disease
Have type 2 diabetes, which can increase how much magnesium you lose in your urine
Take a prescription acid reducer in the proton pump inhibitor family for a long stretch of time, which has been linked to low magnesium
Take a loop or thiazide diuretic, which can increase magnesium losses
Drink alcohol regularly
Are in your later decades, since absorption goes down and losses go up with age
Sweat a lot, whether from hard workouts, hot yoga or a warm workplace
Partner with your provider
You and your healthcare provider are on the same team, and I want you working together. Magnesium is generally well tolerated from food, but supplements are a different conversation, and more is not always better. There is an upper limit for supplemental magnesium, loose stools are the usual first sign of overdoing it, and anyone with reduced kidney function needs real medical guidance before adding magnesium at all, because healthy kidneys are what keep the balance. So bring it to an appointment. Here are five questions worth asking:
Looking at how I eat and how I have been feeling, do you think magnesium is something I should be paying attention to?
Do any of my current medications affect my magnesium, or need to be spaced apart from a magnesium supplement?
Given my kidney function, is a magnesium supplement a safe choice for me?
I am in perimenopause or menopause. How does magnesium fit into supporting my bones, my sleep and my stress right now?
If I do supplement, which form and what timing make the most sense for my situation?
My take
I adore magnesium. I love that it is humble and everywhere, that it lives in the green of every leaf, and that its whole personality is helping other things work.
And it is the clearest proof I have of the thing I keep saying: balance is everything. You can take the best vitamin D in the world and not feel a bit different if magnesium is missing. You can chase potassium and never catch it if magnesium is not there to hold it in place. Nothing in your body operates in isolation, and neither should your approach to taking care of it. Eat the green things and the seeds and the beans. Fill in the gap with a quality supplement in a form that matches your goal. Look at the whole picture, not one line item. That is the holistic approach I believe in with my whole heart, and it is exactly how I love working with women.
Next up in Nutrition A to Z, we stay with the dream team and give the letter P its turn: potassium, the mineral magnesium works so hard to keep in place.
Want help putting the team together? My free Common Supplement Combinations guide walks through which nutrients belong side by side, and my Stress Resiliency Toolkit is there for the part of this post about stress and magnesium. Both are waiting in my free resources library.
This post is for education only and is not medical advice. I do not diagnose or treat any medical condition. Please talk with your healthcare provider before starting any supplement, especially if you are pregnant, nursing, taking medication, or managing a health condition.
Where this comes from
National Institutes of Health, Office of Dietary Supplements: Magnesium fact sheets for health professionals and consumers, including food source amounts and medication interactions
Uwitonze and Razzaque, Journal of the American Osteopathic Association, 2018: "Role of Magnesium in Vitamin D Activation and Function"
Linus Pauling Institute, Oregon State University: Magnesium, and Micronutrient Inadequacies in the US Population
Published clinical literature on the relationship between magnesium status and potassium balance, including work on potassium repletion that does not respond until magnesium is corrected
National Institutes of Health, Office of Dietary Supplements: Vitamin B6, Potassium and Calcium fact sheets