Does coffee wash out magnesium? Facts and myths about magnesium!

There is a lot of conflicting information about magnesium. We often wonder what preparation to choose for cramps or whether coffee leaches magnesium. What about skin absorption during magnesium baths? Our dietitian answers these and other frequently asked questions in the text!

Magnesium – the king of life

Magnesium is an element often called the king of life, not without exaggeration. It performs various and necessary functions for the proper functioning of our body. In the human body, this macronutrient ranks 11th in relation to body weight. The body of an adult human with an average weight of 70 kilograms, according to various sources, contains about 20-25 g and even 35 g of magnesium distributed in:

  • 60% in the skeletal system in the form of magnesium compounds,
    39% intracellularly in muscles
    about 1% extracellularly in other tissues of the body (including blood, about 100 mg).

Magnesium is an activator of over 300 enzymes that participate, among others, in in the metabolism of carbohydrates and fats. In addition, magnesium protects the heart muscle against ischemia and hypoxia, counteracts cardiac arrhythmias, regulates blood pressure, prevents the development of atherosclerosis by lowering blood cholesterol levels, and supports the functioning of our nervous system, contributing primarily to the increased efficiency of our brain. It is also an essential ingredient for bone mineralization and development. But these are just a few of its most important functions for our body.

The need for magnesium

According to the Nutrition Standards for the Polish population of 2020, the recommended daily magnesium intake for men over 18 years of age is 400-420 mg, and for women in the same age category it is 310-320 mg. The recommended intake is the amount of a given mineral that should be provided to the body to cover its daily requirement for a given ingredient. Meanwhile, research shows that the average daily consumption of magnesium in Poland in men is at the level of approx. 350 mg / day, in the case of women the daily consumption is approx. 250 mg. This is mainly due to the increasing degree of food processing, which reduces the magnesium content in products.

Since 1968, the magnesium content of wheat has fallen by almost 20%, which may be due to the acidic soil and the high levels of nitrogen, phosphorus and potassium due to improper fertilization of crops, which makes it difficult for plants to absorb magnesium.

The causes of a magnesium deficiency can also be:

  • Inadequate diet. Even people who consume foods high in magnesium, such as buckwheat, nuts or dark chocolate, may be deficient in magnesium, because many compounds found in food adversely affect the absorption of magnesium in the intestines and reduce its absorption. One of such compounds is phytic acid, found in cereal seeds, legumes and bran. It contains negatively charged phosphate groups that form persistent complexes with metal ions, thus preventing their absorption from the intestine. Phytic acid can reduce magnesium absorption by up to 60%!
    increased loss of magnesium through the kidneys (e.g. in diabetes),
    impaired absorption of magnesium from the gastrointestinal tract, which can be caused by a number of factors, including chronic diarrhea, pancreatic insufficiency, celiac disease, chronic alcoholism, and inflammatory bowel disease.

What is magnesium in?

Magnesium is better absorbed as an ingredient in food products than in preparations, which is why products rich in this element are more valuable. Magnesium is a component of chlorophyll, which is why it can be found in green leafy vegetables such as spinach. In addition to leafy vegetables, good sources of magnesium are: bran, cereal sprouts, whole grains, legumes, nuts, bananas, cocoa and chocolate. Water is also a good source of this macronutrient. It provides about 10% of the daily magnesium requirement of the human body. This share depends, inter alia, on on the magnesium content in the water. Consuming soft, boiled and demineralized water in various types of filtering sets, also at home, reduces the magnesium content in the water.

Magnesium deficiency – symptoms

  • hyperactivity
  • seizures
  • numbness / tingling / weakness
  • aggression
  • bow
  • confusion
  • muscle cramps
  • fasciculations (a short, spontaneous contraction involving a small number of muscle fibers, often causing flickering / waving in a resting muscle)
  • dizziness
  • Heart arythmia
  • bone fragility
  • depression
  • hypertension
  • migraines / headaches
  • reducing the sensitivity of tissues to the action of insulin
  • skin changes
  • loss of appetite / nausea / vomiting

What kind of magnesium for cramps?

The characteristic symptoms of magnesium deficiency are painful muscle spasms, which most often affect the calves. In this case, it is worth considering its supplementation. Here, the key is to choose the right preparation.

Magnesium in dietary supplements is present in the form of salt. We can mention here compounds of the inorganic type (oxide, chloride, nitrate or carbonate) or organic compounds (citrate, ascorbate, aspartate, gluconate or lactate). For magnesium to be most readily available, its compound should be suitably soluble. The most easily soluble are organic magnesium compounds, such as, for example, lactate, citrate or magnesium aspartate. Organic magnesium compounds are characterized by greater solubility in water compared to inorganic compounds, which results in their much greater absorption in the small intestine, reaching the value of 90%.

In turn, in the case of inorganic magnesium compounds present in dietary supplements, it deserves attention Magnesium chloride. It is much more soluble in water than other inorganic salts, and its bioavailability is comparable to that of organic magnesium compounds. It is used orally in slight magnesium deficiencies, as well as therapeutically parenterally, intramuscularly and intravenously in individually determined doses.

An important information when choosing the right preparation is the content of magnesium in ionic form. If one tablet contains e.g. 1000 mg of a magnesium salt and 80 mg of a magnesium salt in ionic form, only the latter value represents the actual magnesium content in the tablet. Therefore, a preparation should be selected that contains the greatest possible amount of magnesium in ionic form. The presence of vitamin B6 (pyrodixine) in the preparation is also important, thanks to which the supplemented magnesium is better absorbed.

Is Magnesium Chloride Absorbed Through The Skin?

The primary function of the skin is to provide a barrier between the body and the external environment. This barrier protects against the penetration of ultraviolet (UV) radiation, chemicals, allergens and microorganisms, as well as the loss of moisture and nutrients in the body. This means that the ability of healthy skin to absorb substances from the outside is very limited. This becomes especially apparent in the limited use of topical medications. To penetrate the skin, the substance must penetrate the epidermis or be absorbed by the sweat glands or hair follicles. Above the dermis there is the epidermis, and on it the stratum corneum, which is lipophilic, i.e. permeable only to substances that are soluble in fat. Therefore, when added to water, magnesium chloride may not exceed this barrier because, when dissolved in water, it becomes an ionic form which cannot pass through the lipophilic epidermal layer.

Nevertheless, a recently published study showed that magnesium ions can penetrate the stratum corneum through the hair follicles and sweat glands. And despite the fact that they constitute only 1% of the total skin surface in total, previous studies have shown that their presence significantly affects the permeability of magnesium. That is why it is not worth giving up magnesium baths, the more so because, in addition to magnesium, they provide us with relaxation and stress relief.

Does coffee wash out magnesium?

For many years, it was believed that coffee had only negative effects. Does coffee really leach out magnesium?

According to studies, consuming 300 mg of caffeine, or about 3 cups of strong coffee, will result in a loss of about 4 mg of magnesium. The theory about the leaching of magnesium in coffee is most likely due to its diuretic effect.

Nevertheless, coffee itself in its composition, apart from caffeine, also contains small amounts of elements, including magnesium. In one cup of decent coffee we will find min. 7 mg of magnesium, so if we drink three cups of coffee a day, we will provide our body with 21 mg of magnesium! If we compare this amount with the 4 mg daily magnesium washout, it turns out that the balance is positive. So there is no need to worry. Drinking coffee does not disturb the concentration of this ion in the blood.


  1. Falk, G., and P. Fatt. “Mechanism of conductance changes produced by the photolysis of rhodopsin.” Experimental eye research2 (1969): 248-249.
  2. Moretti, Antimo. “What is the role of magnesium for skeletal muscle cramps? A Cochrane Review summary with commentary.” Journal of Musculoskeletal & Neuronal Interactions1 (2021): 1.
  3. Gröber, Uwe, et al. “Myth or reality—transdermal magnesium?.” Nutrients8 (2017): 813.