- Magnesium 101
- How much magnesium should we be getting daily?
- Recommended Dietary Allowances for magnesium
- Popular food sources of magnesium
- Benefits of magnesium supplements
- Are there any side effects of taking magnesium?
- Who should consider magnesium supplements?
- My magnesium take-away
For this post in our supplement review series, I looked at the health benefits of magnesium supplementation and then reported on my experiences after 3 weeks of use to see if I could notice any differences.
Here we go.
Magnesium is an essential mineral that our body’s need to be healthy (see our chart below).
It’s a cofactor in 300-plus enzyme systems, including regulating blood sugar levels and blood pressure, and even plays a role in protein synthesis.
Magnesium helps our bones develop and gives us energy, and is important to the transport of calcium and potassium ions throughout our body so we can have regular muscle and nerve control and a normal heart rhythm. As a bonus, magnesium even plays a role in DNA repair. 1
Our kidneys excrete about 120 mg of magnesium into our urine daily; but we “pee out” less when we have less plentiful magnesium in our bodies.
There is an interplay between magnesium and calcium in our bodies. Researchers at the Food and Nutrition Board (FNB) of the Institute of Medicine of the National Academies explain the balance between these two minerals thusly: 2
Since calcium plays an important role in skeletal and smooth muscle contraction, a state of magnesium depletion may result in muscle cramps, hypertension, and coronary and cerebral vasospasms. Magnesium depletion is found in a number of diseases of cardiovascular and neuromuscular function, in malabsorption syndromes, in diabetes mellitus, in renal wasting syndromes, and in alcoholism.
How much magnesium should we be getting daily?
As adults, our bodies contain about 25 grams of magnesium at any given time, 60% of which is in our bones, and nearly all the rest in our soft tissue. 3
Less than 1% of magnesium is found in our blood, which makes it difficult to test for a magnesium deficiency; however, dietary surveys have shown that most people don’t get enough of this essential mineral through their food alone. 4
Dietary Reference Intakes developed by the FNB based on age and sex suggest the following recommended intakes.
Recommended Dietary Allowances for magnesium
|Birth to 6 months||30 mg||30 mg|
|7-12 months||75 mg||75 mg|
|1-3 years||80 mg||80 mg|
|4-8 years||130 mg||130 mg|
|9-13 years||240 mg||240 mg|
|14-18 years||410 mg||360 mg||400 mg||360 mg|
|19-30 years||400 mg||310 mg||350 mg||310 mg|
|31-50 years||420 mg||320 mg||360 mg||320 mg|
|51+ years||420 mg||320 mg|
Source: Food and Nutrition Board
Just 30-40% of the magnesium we consume from food sources is absorbed by our body. 5
Magnesium is mostly found in nuts, leafy vegetables, soy milk, whole grains, and fortified breakfast cereals. Here are a few more good dietary sources.
Popular food sources of magnesium
|Food||Milligrams (mg) per serving||Percent DV|
|Almonds (dry roasted), 1 ounce||80||20|
|Spinach (boiled), 1/2 cup||78||20|
|Cashews (dry roasted), 1 ounce||74||19|
|Peanuts (oil roasted), 1/4 cup||63||16|
|Soy milk (plain or vanilla), 1 cup||61||15|
|Black beans (cooked), 1/2 cup||60||15|
|Edamame (shelled, cooked), 1/2 cup||50||13|
|Peanut butter (smooth), 2 tablespoons||49||12|
|Bread (whole wheat), 2 slices||46||12|
|Avocado (cubed), 1 cup||44||11|
|Potato (baked, with skin), 3.5 ounces||43||11|
|Rice (brown, cooked), 1/2 cup||42||11|
|Yogurt (plain, low fat), 8 ounches||42||11|
|Breakfast cereals, fortified with 10% of the DV for magnesium||40||10|
|Oatmeal (instant), 1 packet||36||9|
|Kidney beans (canned), 1/2 cup||35||9|
|Banana, 1 medium||32||8|
|Salmon (cooked), 3 ounces||24||6|
|Milk, 1 cup||24-27||6-7|
|Halibut (cooked), 3 ounches||24||6|
Source: U.S. Department of Agriculture
Because we may not get enough magnesium through our food, supplements can be helpful for some people.
Benefits of magnesium supplements
#1: Exercise and recovery
I’ve been pretty obsessed with spin classes lately, and I just bought a bike for leisurely rides outside. After the gym, I feel pretty invigorated, but a bit sluggish a day later. My legs hurt depending on the day, even though I don’t feel like I’ve done my workout any differently.
One study of 23 competitive triathletes who were given magnesium supplements over four weeks found their swim, bike, and run times had improved versus those given just a placebo, and they also had a reduced stress response. 6
Although I am not a competitive athlete, far from it, since taking magnesium I’ve noticed less general aches and pains post-workout. Lactic acid buildup is a huge issue during spin classes, in particular, and we only stretch for a couple of minutes afterward.
In a study in rats (so take with a grain of salt) Magnesium has been shown to help dispose of the number one culprit of post workout soreness: lactic acid. 7
Exercise redistributes the magnesium in our bodies so we can more effectively use it during this period of oxidative stress; we also tend to sweat and excrete more magnesium in urine when we’re physically active, which may increase our magnesium requirements by 10-20%. 8
#2: Mood booster
While I don’t suffer from depression on a regular basis, magnesium seemed to give me a mood boost. My mood always felt pretty uplifted the past three weeks, except on the couple of days I wasn’t taking my supplement because I forgot (hello, weekend).
Was this just placebo? Maybe, but we do have studies which indicate magnesium can be a mood booster.
Because magnesium is critical to our brain health, researchers think it may have a big effect on those with depression — in fact, they’ve known this for 100 years or longer. 9
Adults with depression have been found to be low on the intake of magnesium. 10
One study of two dozen older adults with depression and a magnesium deficiency found that magnesium supplements worked just as well for treatment as an antidepressant. 11
Definitely something to be said for a potential natural alternative to medications that can come with a wide range of unpleasant side effects.
#3: Relieve PMS symptoms
I don’t have the nickname “Tiger” at work for no reason. I’m a hardworking and fairly passionate person who can get irritated easily, and when it’s that time of the month, it’s worse.
Magnesium has been shown to reduce some of the symptoms of premenstrual syndrome (PMS), including irritability, cramps, bloating, and general fatigue. One study of women my age (24-39) found that after taking magnesium supplements for 2 months and two menstrual cycles, the women recorded fewer mood changes, 12 while another two-cycle study showed reduced weight gain, fluid retention, and breast tenderness among participants who took 200 mg of magnesium daily. 13
While my experience with magnesium is just based on the past three weeks, I did notice a reduction in my usual PMS symptoms — and am dreading next month even less.
#4: Reduces anxiety and promotes sleep
After a long day of work, sometimes I have trouble falling asleep. I get small bursts of energy throughout the day normally — nothing very consistent until taking magnesium — and experience “crashes,” as well.
Magnesium can help reduce anxiety, calm you down, and in general help you get to sleep. I often don’t feel refreshed when waking up, which typically means you’ve got something going wrong while you sleep (not getting enough of the good stuff, like REM or deep sleep, or you’re not sticking to a schedule to help your body’s circadian rhythm). Nutrient intake can affect our sleep, which is something I hadn’t taken into consideration until this experiment. Sleep efficiency, sleep time, and melatonin production have all been shown to increase as we take in more magnesium. 14
While I can be all over the place in terms of sleep and energy, it’s been a lot easier to tell my body when it’s time to go to bed and when to wake up — naturally.
#5: Can relieve constipation
When you’re constipated, you’d think that fiber has everything to do with it. Not true. It could be magnesium and how much you’re getting.
In a study of nearly 4,000 Japanese women (ages 18 to 20 and dietetic students), more than 1 in 4 were found to have functional constipation — constipation without a physical cause. Their dietary fiber and water intake were not associated with this condition, but low magnesium intake was. 15
As we’ve written about previously, a healthy microbiome can have a big effect on our overall health. In addition to constipation, magnesium deficiencies also have been shown to alter gut microbiota in mice, inducing anxiety and depressive behavior — tying a few of these top five benefits together. 16
While I told John I would never write about my bathroom life for Gene Food, I will say my gut has felt in tip-top shape the past 3 weeks. Probably partly diet, but maybe thanks to magnesium!
Are there any side effects of taking magnesium?
In a word, yes.
Magnesium is the primary ingredient in some laxatives, and also used in some medicines that relieve heartburn and indigestion symptoms.
So it’s natural that, well, if you are getting a lot of magnesium from your food and taking supplements, well past the recommended daily amount, you may feel those sort of effects, including:
- Stomach discomfort
Some of us may find that chelated magnesium and supplements that use glycinate, citrate and malate chelates are easier on the stomach than cheaper preparations that use magnesium oxide.
Our kidneys do take care of us when it comes to eliminating magnesium on a regular schedule, though, so as long as you are otherwise healthy and taking the recommended amount, you should be safe. The FNB’s recommendation for supplemental magnesium is up to 350 mg per day for healthy adults, male or female (pregnant or breastfeeding).
If you’re on some types of medication, including antibiotics, magnesium may interact with these drugs or affect its absorption.
If you have any concerns with your magnesium intake, you should speak with your doctor.
Who should consider magnesium supplements?
Generally, if you’re otherwise healthy, you won’t experience any real symptoms of a magnesium deficiency — loss of appetite, nausea, vomiting, fatigue, weakness — though people with certain health conditions or chronic alcoholism may, extending to muscle cramps, seizures, coronary spasms, and even personality changes.
So for me, magnesium supplements were an extra “feel-good” added into my daily routine that helped me feel better while exercising, improved my sleep, and relieved PMS symptoms.
People at risk of a magnesium deficiency who may want to consider supplements after speaking with a doctor include: 17
- Those with gastrointestinal diseases, including Crohn’s disease and celiac disease;
- Those with type 2 diabetes or who are insulin-resistant;
- Those with alcohol dependence;
- Those who are older, as our gut absorbs less magnesium as we age while our kidneys also excrete more. 18
But even if you don’t fall into those groups, it might be a good idea to determine your magnesium intake and see if you should be getting more. Those who habitually do not get enough magnesium may be at a greater risk for developing illnesses over time, including hypertension, diabetes, osteoporosis, and migraines.
My magnesium take-away
After my research for this post, it’s clear that many people just aren’t getting enough magnesium in our diets, and our bodies’ inability to absorb magnesium puts us at a disadvantage when we only consume magnesium via food sources. No matter how many bowls of spinach or handfuls of almonds you eat per day, it may not be enough, especially since modern day farming has depleted the soil of essential minerals.
For the past three weeks, I took 235 mg of magnesium chelate, the highest form of magnesium supplement available that is essentially just like getting magnesium from a food source, in terms of absorption rate. I need 320 mg daily for my age, so with food, I’m right where I should be now.
In addition to remembering to make a few healthy choices for meals, it’s been a no-brainer to add magnesium supplements to my daily routine.