Magnesium 13 frequently asked questions

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There is no question that magnesium is an important mineral. But as a strength athlete, do you have to take in a lot of it? And do you (so) benefit from a magnesium supplement? The answers to these and several other questions about magnesium.

Key points:

1.   Magnesium is one of the most important minerals in our body. It is involved in numerous processes, including the proper functioning of the muscles.

2.   With a magnesium deficiency, stiff muscles and cramps are the result. A deficiency also leads to fatigue, which can be at the expense of performance during strength training.

3.   (Strength) athletes need more magnesium than non-active people, who need 300 to 400 milligrams of the mineral daily.

4.   Magnesium is found in many foods that you consume every day, such as wholemeal bread and other wholegrain cereal products, vegetables, nuts, milk and dairy products and meat. You will therefore not soon have a shortage, especially if you are in the ‘bulk’ as a bodybuilder.

5.   The risk of a (small) magnesium deficiency is real if you follow a long-term calorie-restricting diet as an athlete, for example as a bodybuilder in the cut. In that case, err on the side of caution by taking a magnesium supplement.

6.   Take a supplement with a magnesium compound that guarantees high absorption: magnesium citrate, malate, taurate, glycinate, lactate or gluconate. Avoid the poorly absorbable magnesium sulfate and oxide.

7.   Better not take magnesium and calcium together.


  1. What is magnesium?
  2. What does magnesium do?
  3. What does magnesium do specifically for muscles and strength?
  4. Which foods contain magnesium?
  5. How much magnesium do you need daily?
  6. What happens if you don’t get enough magnesium?
  7. Do (strength) athletes need more magnesium?
  8. Do you need a magnesium supplement as a bodybuilder?
  9. How much magnesium should you take when taking a supplement?
  10. What if you get too much magnesium?
  11. Which form of magnesium is best?
  12. Is it helpful to take magnesium along with calcium?
  13. Do magnesium supplements help with sleeping problems?


Magnesium is one of the most important minerals in our body. Minerals are salts that arise from dead nature. They are important for your body tissues, your nerve functions, bones and teeth, among other things. Your body cannot make minerals on its own. So you have to get them through your diet or in the form of supplements.

Magnesium is the fourth largest mineral in the body in quantity, after calcium, potassium and sodium. The body contains approximately 21 to 28 grams of magnesium. About half of it is in the bones, while the rest is in the organs and cells.


Magnesium controls more than 300 different enzymes. These enzymes ensure that all kinds of processes in your body run smoothly, such as:

  • the breakdown of glucose and fat;
  • the production of proteins, enzymes and antioxidants such as glutathione;
  • the production of DNA and RNA (macromolecules in which hereditary properties are recorded);
  • regulating cholesterol production;
  • the relaxation of muscles, nerves and blood vessels;
  • the transmission of nerve impulses and proper functioning of the muscles;
  • the formation of healthy teeth and bones;
  • increasing resistance to tension and stress;
  • strengthening memory and concentration;
  • promoting cardiovascular health.


As mentioned, magnesium plays an important role in the transmission of nerve impulses and the proper functioning of the muscles. Magnesium works closely with another mineral: calcium.

Where calcium causes your muscles to contract, magnesium causes your muscles to relax. So there is an interaction between calcium and magnesium.

A magnesium deficiency results in stiff muscles and cramps. A deficiency also leads to fatigue, which of course does not benefit performance during strength training. As a strength athlete, it is therefore very important to get enough magnesium.


Magnesium is found in many foods, making it easy to meet your daily needs (see question 5 ). Magnesium is found in wholemeal bread and other wholegrain cereal products, vegetables, nuts, milk and dairy products and meat. It is even in ‘normal’ tap water.

Some commonly consumed foods that contain a lot of magnesium are:

  • unsalted peanuts (1 handful of 25 grams contains 54 milligrams of magnesium)
  • cooked spinach (78mg/100g)
  • cooked whole wheat pasta (28 mg / 60 g)
  • chicken breast cooked (25 mg / 70 g piece)
  • wholemeal bread (19 mg / slice of 35 g)
  • banana (37 mg/piece)
  • Brinta (80mg/100g)
  • peanut butter (32 mg / 20 g serving)
  • semi-skimmed milk (18 mg / glass of 150 ml)
  • cottage cheese (50 mg / 500 g container)
  • broccoli (20mg/100g)
  • avocado (50mg/piece)
  • rice (12mg/100g)

Not all magnesium in food is actually absorbed by the body. This is because the magnesium in food is bound to all kinds of substances, so that the digestive system has to make considerable effort to absorb magnesium. The absorption of magnesium from the diet varies from 20 to 60% i ] . Sufficient and sufficiently varied food is therefore a requirement to get your required magnesium intake.


According to the Health Council (2018), adult men should consume 350 mg of magnesium daily and adult women 300.

Magnesium requirement may also be related to body weight. Studies speak of 5 or 6 mg of magnesium per kg of body weight per day. In practice, this amounts to 300 to 400 mg per day for most people, in accordance with the recommendation of the Health Council ii ][ iii ] .

Your body always tries to keep the magnesium level as optimal as possible. When your magnesium level is very high, your body excretes more magnesium and absorbs less. If your magnesium level is low, less is excreted and more is absorbed iv ] . We also call this auto-regulation. That does not mean that you should try to get 300 or 350 mg of magnesium daily through your diet.

Your body absorbs less magnesium if you eat excessive amounts of sugar, alcohol, fats, proteins and/or calcium v ] . There is a lot of calcium in cheese, seeds and nuts (see also question 12).


A magnesium deficiency can lead to:

  • listlessness
  • (over) fatigue
  • muscle cramps
  • restless legs
  • a low calcidiol level (too little vitamin D)
  • cardiac arrhythmias in extreme cases

According to the Nutrition Center , the average person gets enough magnesium i ] . Not according to a US study. Of the 8,437 participants in the study, about half were deficient vi ] . American eating habits are probably partly to blame for this. According to the Nutrition Center, you should be able to meet your magnesium needs without any problems with a healthy European diet according to the famous Wheel of Five. A deficiency can arise if, for example, your kidneys or intestines function poorly.


Yes. Athletes need 10 to 20 percent more magnesium than non-active people. This is because exercise is associated with sweating and more frequent urination, where magnesium is lost. If you, as an avid athlete, consume less than approximately 250 mg of magnesium per day, a deficiency could already arise. And just a small deficiency leads to poorer performance in athletes vii ] .

We also saw that magnesium plays a role in the functioning of muscles, which is why it is extra important for strength athletes to get enough magnesium. Bodybuilders are also often heavyweights, so they may need even more magnesium than the average person. After all, some guidelines refer to 5 or 6 mg of magnesium per kg of body weight per day – see question 5 .

Finally, like zinc, magnesium also contributes to the production of IGF-1 (insulin-like growth factor), a substance produced by the growth hormone HGH that plays an important role in muscle growth ix ] .


Not necessarily. It depends on your diet, especially if you are bulking or cutting.


Although as a bodybuilder you need more magnesium than the ordinary person (see question 7) you will probably also eat much more in the bulk than the ordinary person. Bodybuilders often eat up to 1000 kcal above their maintenance (kcal that you burn with strength training + extra kcal to facilitate muscle growth, the ‘bulk surplus’). In addition, their diet often contains products that contain a lot of magnesium, such as chicken breast, cottage cheese, nuts, bananas, Brinta and spinach. If you are not sure whether you are getting enough magnesium, it may be enough to include (some) more of these food products in your diet.

It is difficult to determine whether you really consume enough magnesium. You can do the math, but you never know exactly how much magnesium from your diet is actually absorbed by your body. But again, if you are bulking and work in, for example, 3500 kcal per day, you probably don’t have to worry about your magnesium intake. In addition, we saw that our body is to a certain extent self-regulating, so that it excretes less magnesium and absorbs more in the event of an impending deficiency.

Of course, if you mainly eat junk food during your bulk, it’s a different story. But then you probably not only lack magnesium, but also other vitamins and minerals. Although it does not matter what you eat for body composition, as long as it is in the right amounts (If It Fits Your Macros), we advise you to eat healthy in the basics.


If you practice sports with a calorie-restricted diet, such as bodybuilders do in the cut, supplementation of vitamins and minerals can sometimes be necessary or at least offer extra security, especially with a large calorie deficit and especially if you also do a lot of cardio. If you eat less than 2000 kcal per day and also exercise a lot, you run the risk of getting too little magnesium viii ] . Although many people often eat healthier if they follow a calorie-restricted diet and therefore may get more than enough of their micronutrients.

If you consume too little magnesium during cutting, this can lead to fatigue and muscle cramps, and possibly also to less good sleep (see question 13). Things that you can not use if you have a long-term energy deficit and also have to continue training rigidly to maintain your muscle mass. Supplementation may then offer a solution, although you can also try to take more food that contains a lot of magnesium. Magnesium from food may be better utilized by the body than magnesium from supplements v ] .


The Nutrition Center and the European Food and Consumer Product Safety Authority advise not to supplement with more than 250 milligrams per day i ] . Of course you can also start with a smaller dose and see how you react to it.

Magnesium from supplements is absorbed much better by your body than from food. The extent to which depends on the type of magnesium compound (see question 11 ).

Instead of a separate magnesium supplement, you can also use a multivitamin in the cut. Handy, because it also contains many vitamins and minerals that you may also need extra. However, such a multivitamin usually only contains around 50 mg of magnesium, which is relatively scanty as a supplement.

Among bodybuilders, ZMA, a combination of zinc, magnesium and vitamin B6, is popular. In principle a great option if you want to supplement all three substances. Usually, one dose provides around 150 milligrams of magnesium. ZMA is also often touted as a testosterone booster, but there isn’t enough scientific research to back up that claim.


If you have too much magnesium in your body, despite the autoregulation, it can lead to intestinal complaints, such as diarrhea. If you suffer from this after you have started supplementation, there is a real chance that you are taking in too much magnesium.


There is a variety of magnesium compounds that are used in supplements. The difference between those compounds mainly lies in the absorbability of the magnesium.

Organically bound magnesium is better absorbed than inorganic magnesium forms. For example, the inorganic compound magnesium sulphate has an absorbability of only 4%. Magnesium oxide is also not recommended. Although this compound has the greatest magnesium density, the absorbability is also only a few percent x ][ xi ] . Keep this in mind if you are going to buy a supplement. We saw that some (web) stores still offer high-priced jars of magnesium oxide!

The forms of magnesium that have the best absorption are malate, taurate and glycinate. But the most common compound in supplements today is magnesium citrate. That is magnesium in salt form combined with citric acid. Citrate is also well absorbed by the body, but slightly less well than the three mentioned xii ] . Magnesium lactate and gluconate are also easily absorbable compounds.

Oral magnesium supplements usually come as a tablet, chewable tablet, or capsule, as well as a powder.


Not really. Both minerals are important for strong bones, proper muscle and nerve function, and controlling your blood pressure. They even work closely together for your muscle function, as we have already seen.

However, minerals also have the property of competing with each other. If you take large amounts of magnesium and calcium at the same time, the absorption of one mineral can be at the expense of the other xvi ] . Moreover, a possible magnesium deficiency does not mean that you should also supplement calcium. There is a lot of calcium in dairy, so if you eat a lot of cottage cheese and the like during the cut – to keep your protein intake up – you don’t have to worry about a calcium deficiency. If you do want to take extra calcium, take it as a separate supplement, separate from magnesium.


Magnesium is often burned in with sleep. Not without reason: By helping to relax the nervous system, magnesium can help prepare your body and mind for sleep. Magnesium regulates the so-called neurotransmitters, which send signals through the nervous system and the brain. The mineral also regulates the hormone melatonin, which plays a role in your body’s sleep-wake rhythm. Finally, magnesium binds to gamma-aminobutyric acid (GABA) receptors, neurotransmitters responsible for calming nerve activity. It is the same neurotransmitter used by certain sleep medications xiii ] .

Magnesium is therefore important for your sleep, but that does not mean that it is a remedy for sleeping problems. A magnesium supplement can only help you sleep better if you are magnesium deficient xiv ] . And the latter is not the case for most people. However, we saw in question 8 that as a bodybuilder you can more quickly have to deal with a (small) magnesium deficiency, especially when you combine training with a calorie-restricted diet. In that case, magnesium supplementation may also contribute to the quality of your sleep, which is important for recovery from your training!


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