Evidence: Very High Possible Benefits: Very High Safety: Very High
TABLE OF CONTENTS
What is magnesium?
Magnesium is an essential mineral necessary for hundreds of functions n the body. Magnesium supplements are most helpful if you are deficient in this nutrient. If you already get enough from food, you should not need to take it as a supplement. However, it can still improve some aspects of your health beyond the baseline. This article is about the main benefits of magnesium supplements, their potential side effects, the best time to take them, and more.
What does magnesium do?
Magnesium plays a vital role in every part of the body.
It is needed to create all proteins in the body. Proteins are essential to make virtually anything else in the body, including muscles, organs, enzymes, and hormones. None of these would exist without magnesium.
This mineral is also needed to make and utilize energy. It stabilizes adenosine triphosphate (ATP) molecules which are the source of energy at the cellular level. On its own, ATP would not be able to perform any of its functions. It needs to pair with magnesium to perform all of them.
Magnesium partners with ATP to distribute calcium, sodium, potassium, chloride, and phosphate to the right places. It allows calcium and phosphorus to travel into bones as opposed to other places where these minerals could contribute to soft tissue calcification. It also helps the kidneys get rid of excess phosphorus and sodium, which can prevent high blood pressure related to too much sodium and other health risks.
Possible benefits
It is important to note that all of the potential benefits mentioned below are dose-dependent. Generally, the higher the dose, the more pronounced the effects are. However, they do reach a plateau at a certain point. We will discuss the best dosing protocol later in this article.
Many possible benefits fall under the umbrella of ‘correcting a deficiency’ and are therefore not mentioned in the article. If you are deficient, magnesium supplements can affect your cognition, performance, and overall health in a remarkably positive way.
Major benefits
Correcting or preventing a deficiency – Magnesium deficiency can be terrible for health and overall quality of life. Fortunately, a severe deficit is relatively rare. A mild deficiency is much more common and can lead to many problems mentioned later in the article. If you are experiencing symptoms of deficiency or know that your magnesium levels are too low, helping you get back to the optimum is the main benefit of magnesium supplements.
Reduced soft tissue calcification related to CKD – Patients with chronic kidney disease tend to develop soft tissue calcification. Magnesium supplements are very helpful for preventing or lowering this effect even if one is not deficient in this mineral. One study found that supplementing with 720 mg/d works better than 360 mg/d.
Minor benefits
Reduced migraines – Magnesium supplements are highly effective for preventing and lowering the intensity of migraine headaches. 600 mg/d tends to be more effective than lower doses.
Lowered blood pressure – Magnesium is necessary to get rid of excess sodium which can contribute to high blood pressure. 700 mg/d seems to work best for most people although lower doses are effective as well.
Laxative effects – While this can be considered a negative, magnesium supplements can act as laxatives and help people with constipation. The most useful forms in this regard are magnesium oxide, hydroxide, and sulfate.
Muscle recovery – Perhaps the best form for muscle recovery is magnesium chloride. It should be used topically after a workout or an injury. Oral supplementation can also help but may not be as effective unless you are deficient in Mg.
Reduced asthma – Supplementation with Mg reduces asthmatic symptoms to a small extent.
Reduced blood glucose – Supplementation slightly lowers blood glucose levels in diabetics. Unfortunately, this benefit is small and doesn’t seem to apply to healthy people.
Improved aerobic exercise – One study found a notable improvement in aerobic exercise capacity in triathletes. Mg supplements have also been shown to increase muscle oxygenation.
Improved sleep quality – This effect only applies to people with poor sleep or those deficient in this mineral.
Reduced symptoms of depression – This effect has been found in older diabetics but may also apply to other groups if they are deficient in the nutrient.
Possible side effects
These side effects are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.
Diarrhea – While all magnesium supplements can cause this side effect, some forms are more likely to cause diarrhea than others. The most problematic ones in this regard are magnesium oxide, sulfate, and chloride. Diarrhea caused by this supplement is not dangerous, assuming it doesn’t lead to severe dehydration. You can lower the risk of diarrhea by taking the supplement with food and spreading the dose to multiple smaller doses.
Low blood pressure – High doses (typically 900 mg/d or more) can cause your blood pressure to drop too low, especially if you consume too little sodium.
Twitching and muscle spasms – This effect is also usually caused by the depletion of sodium.
Abnormally slow or fast heart rate – This is a rare side effect but possibly the most dangerous one. It is also likely caused by electrolyte imbalances and it should only apply to higher doses.
Nausea – Just like diarrhea, this side effect is not dangerous but can be unpleasant.
Contamination – Contaminated supplements are uncommon in the USA and other well-regulated countries. However, if you wish to buy products from China, India, or other countries without strict regulations, beware that the supplements may be contaminated. Either way, you need to choose the brand you order from wisely. It is highly recommended to check the certificates or read through some reviews for the specific product before you buy it. The FDA (Food and Drug Administration) has the power to regulate dietary supplements but can only do so after they have been on the market for a while. That’s because supplement companies are not obligated to announce to the FDA when releasing a new product on the market. The FDA has to discover the product and test it for potential impurities, which can take a lot of time. During that time, the supplement can be sold on the market even if it’s impure. Also, supplement companies can change their manufacturers without announcing it to the FDA.
Who should not take magnesium?
You should probably avoid taking the supplement if you:
have kidney problems other than chronic kidney disease
suffer from low blood pressure
already consume enough magnesium from food
experience a severe adverse reaction after taking the supplement
Who will benefit the most?
You should consider taking the supplement if you:
experience symptoms of deficiency, or you know you are deficient based on blood tests
exercise or use a sauna (magnesium, as well as other electrolytes, get lost through sweating)
don’t get enough from food (the easiest way to find out how much of this nutrient you are getting in your diet is to track your food intake for a while with Cronometer.com)
drink alcohol (alcohol hurts the absorption of Mg and increases its loss through urine)
are refeeding after a prolonged fast (magnesium can be pushed into cells when you refeed, causing blood levels to drop too low)
are on a ketogenic, carnivore, or autoimmune paleo diet (it is extremely hard to get the optimal amount of magnesium on these diets, especially the latter two)
are deficient in calcium or vitamin D (When the body runs low in calcium, parathyroid glands create parathyroid hormone (PTH) to increase calcium levels in the blood. Mg is needed to create PTH. PTH is also necessary to activate vitamin D but cannot do so without magnesium. Put simply, magnesium deficiency can contribute to a deficiency in calcium and vitamin D.)
take antibiotics, antifungals, or anticancer drugs (many of these hurt magnesium absorption)
have a high budget for supplements (assuming that the supplement doesn’t contain impurities, it appears to be safe in most cases and rarely does more harm than good if you stick to regular doses)
Symptoms of magnesium deficiency
About 60-80% of the population is deficient in this mineral.
The most common signs of deficiency include:
fatigue and weakness
muscle cramps
muscle spasms
muscle tension
irregular heartbeat
stress
anxiety
obesity
asthma
pain
glutamate sensitivity
migraines
severe PMS symptoms
depression
loss of appetite
shaking
Keep in mind that these signs are just indications of a deficiency. If you experience some or even most of them, it does not necessarily mean you need more magnesium. On the other hand, some people may be deficient even though they are completely asymptomatic.
With that said, if you experience many or most of these symptoms, there is a high chance that you are not getting enough magnesium. The more of these symptoms you have and the more severe they are, the more likely you are to have a deficiency.
Types of magnesium
There are many types of magnesium supplements:
Magnesium oxide – This is the cheapest form found in most supplements that contain Mg. Unfortunately, it is about 3 times harder to absorb than most other forms and even low doses may cause diarrhea. This form is most useful as a laxative but it is worse than most other forms for increasing magnesium status.
Magnesium hydroxide – This form, also called Milk of Magnesia, is virtually identical to Mg oxide but even more laxative.
Magnesium chloride – This form is not advised as an oral supplement because of its poor absorption. However, it appears to be highly effective when used topically as a gel, spray, or oil. The main benefit of this form is muscle recovery after a workout or an injury.
Magnesium sulfate – Also known as Epsom salt, this form is often used topically by adding it to bathing water. Unfortunately, Epsom salt baths aren’t very effective for absorbing Mg. You could technically take magnesium sulfate orally but it doesn’t absorb well and is the most likely form to cause diarrhea. It is best to stay away from this type.
Magnesium L-threonate – This form doesn’t contain much Mg but it is great for cognitive enhancement because of the threonate part.
Magnesium citrate – This type often comes as a powder and is very cheap. It absorbs about as well as Mg from food and is the best form to take if you are on a budget.
Magnesium malate – This form is likely just as good as Mg citrate.
Magnesium gluconate – This form absorbs just as well as Mg citrate and malate. One study on rats shows it is even more absorbable but the study isn’t too reliable.
Magnesium glycinate – This form is also known as magnesium bisglycinate and chelate. It is the best one for improving sleep quality because of glycine. People also claim that this form is the least likely to cause diarrhea.
Magnesium lactate – Mg lactate may be just as good as Mg citrate or malate but isn’t as researched.
Magnesium aspartate – The absorption of this form is somewhere in-between magnesium oxide and citrate. Magnesium monoaspartate absorbs better than Mg citrate (42% bioavailability vs. citrate’s 30%) but is rarely used and hard to obtain.
Magnesium taurate – This form may possess some benefits of taurine, such as improved blood flow.
Magnesium orotate – This form has a large safety profile but we don’t know how well it absorbs.
Magnesium carbonate – This form can be found in Calm magnesium and dolomite.
Magnesium bicarbonate – Some claim this form is better since it naturally occurs in most sparkling water. This form is likely just as good as most other forms but there are no studies showing it is superior in any way to Mg citrate or other good forms.
Of all the supplemental forms, magnesium citrate is the best for most people because of its low price, high absorption, and safety profile. Malate, gluconate, lactate, bicarbonate, and orotate seem to be just as good but not better.
Magnesium glycinate is more expensive but also slightly better if you’re taking the supplement to improve sleep quality.
Magnesium L-threonate is a great choice for those prioritizing cognitive health but it is not as effective for increasing Mg levels and correcting a deficiency.
Stay away from magnesium oxide, hydroxide, and sulfate unless you have a good reason to choose these forms. They are not as effective for increasing Mg levels but can be useful as laxatives.
How much magnesium should you take?
The RDA (recommended daily allowance) for this nutrient is 400 mg/d for adult men and 310 mg/d for women. For those over the age of 30, the RDA increases to 420 mg/d for men and 320 mg/d for women. These amounts should be enough for most people to avoid symptoms of deficiency. The RDA for pregnant and lactating women is 360 mg/d and 320 mg/d, respectively.
While 400 mg/d is usually enough to prevent a deficiency, 600-800 mg appears to be the best daily target for optimal health. This amount should provide most of the benefits without meaningful side effects.
Beware that some things increase your need for magnesium. These include chronic kidney disease, sweating, vomiting, diarrhea, antacids, proton pump inhibitors, and more.
Magnesium oxide, sulfate, and hydroxide absorb about 3-5 times worse than magnesium from food. Most other forms, such as citrate and malate, absorb about as well as magnesium from food.
The upper safety limit for Mg supplements is 350 mg. Higher amounts may cause problems if you take the supplement for a prolonged period. Taking more than 400 mg daily should not be necessary and is not recommended unless you have a great reason to do so.
Food sources of magnesium
The richest food sources include rice bran, wheat bran, soy flour, hemp seeds, pumpkin seeds, watermelon, and many spices. These provide over 420 mg (the RDA for adult men) in less than 100 grams.
Legumes, nuts, seeds, and grains usually give you enough magnesium in 200-400 grams of dry weight. The same can be said about a few types of vegetables.
While legumes, nuts, seeds, and grains are the richest food groups, they also contain phytic acid, an antinutrient that makes magnesium less bioavailable. Soaking, sprouting, fermenting, or souring these foods will improve the absorption of magnesium.
Fats, oils, dairy, meat, and eggs contain little to no magnesium. The only way to get enough on a high-fat diet is to include vegetables rich in this mineral, such as cruciferous vegetables or leafy greens. Those on a carnivore diet would have to get magnesium from supplements or mineral water as no animal food can provide enough magnesium for optimal health.
The easiest way to find out how much magnesium you are getting in your diet is with Cronometer.com. This free app allows you to track all vitamins, minerals, and more.
Best time to take magnesium
The nutrient is water-soluble so you don’t have to take it with food to absorb it well. Taking the supplement with food is better if it causes stomach upset or diarrhea when you take it on an empty stomach.
Taking the supplement in the evening may lead to slightly better sleep quality than if you take it earlier in the day. However, the difference is tiny.
Interactions with other supplements
Vitamin D Magnesium is necessary to absorb and utilize vitamin D. Not enough of this mineral can contribute to vitamin D deficiency or symptoms resembling it.
Where to buy magnesium
Amazon seems to be the best option for ordering magnesium supplements in most countries. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the internet.
Beware some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.
FAQ
You can take the supplement daily and do not need to cycle it. However, it is certainly not a problem if you don’t take it daily. Not taking the supplement every once in a while could lead to better absorption.
All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes some time that can add up over months or years. The disadvantage of capsules is that they often contain bovine gelatine, which rarely comes from an ethical source.
Yes. The nutrient doesn’t impact your sleep in any negative way in the short term.
The supplements should not become harmful once they exceed the expiration date, but they can lose potency over time.
Keep the supplements in a cold, dark, and dry place, and they should remain just as potent for many months or even years.
While toxicity is rare, too much magnesium in the system can cause some problems, such as diarrhea, low blood pressure, and irregular heartbeat. It is best to stay below 800 mg a day to prevent these side effects.
Of all the supplemental forms, magnesium citrate is the best for most people because of its low price, high absorption, and safety profile. Malate, gluconate, lactate, bicarbonate, and orotate seem to be just as good but not better.
Magnesium glycinate is more expensive but also slightly better if you’re taking the supplement to improve sleep quality.
Magnesium L-threonate is a great choice for those prioritizing cognitive health but it is not as effective for increasing Mg levels and correcting a deficiency.
Stay away from magnesium oxide, hydroxide, and sulfate unless you have a good reason to choose these forms. They are not as effective for increasing Mg levels but can be useful as laxatives.
The most common reason people become deficient is that they don’t get enough of this nutrient from their diet. However, many things can hurt your magnesium status and increase your need for this nutrient. These include obesity, chronic kidney disease, sweating induced by sauna or exercise, and more.
You may need more of the nutrient if you: – experience signs of deficiency, or know that you are deficient from blood tests – don’t get enough from food (the easiest way to find out how much of this nutrient you are getting in your diet is to track your food intake for a while with Cronometer.com) – are deficient in calcium or vitamin D (When the body runs low in calcium, parathyroid glands create parathyroid hormone (PTH) to increase calcium levels in the blood. Mg is needed to create PTH. PTH is also necessary to activate vitamin D but cannot do so without magnesium. Put simply, magnesium deficiency can contribute to a deficiency in calcium and vitamin D.) – drink alcohol (alcohol hurts the absorption of Mg and increases its loss through urine) – are refeeding after a prolonged fast (magnesium can be pushed into cells when you refeed, causing blood levels to drop too low) – exercise or use a sauna (magnesium, as well as other electrolytes, get lost through sweating) – take antibiotics, antifungals, or anticancer drugs (many of these hurt magnesium absorption) – are on a ketogenic, carnivore, or autoimmune paleo diet (it is extremely hard to get the optimal amount of magnesium on these diets, especially the latter two)
The half-life of magnesium in the body is about 42 days.
In the long term, it typically takes about 2 weeks of taking the supplement to begin noticing the benefits.
Most magnesium supplements on the market are vegan-friendly but always check the label to be sure. If you buy the mineral in a capsulated form, beware that the capsules often contain animal-based gelatine. Instead, find a brand that puts its products into cellulose capsules.
The nutrient is water-soluble so you don’t have to take it with food to absorb it well.
No, it doesn’t. The supplement does not interfere with fasting in any significant way.
References
Most of the information provided in this guide is supported by scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything said in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.
