Magnesium is an essential dietary mineral, and the second most prevalent electrolyte in the human body. Magnesium deficiencies are common in developed countries. A deficiency increases blood pressure, reduces glucose tolerance and causes neural excitation.
Magnesium deficiencies are common in the western diet because grains are poor sources of magnesium. Other prominent sources of magnesium, like nuts and leafy vegetables, are not eaten as often. It is possible to fix a magnesium deficiency through dietary changes. If magnesium is supplemented to attenuate a deficiency, it acts as a sedative, reducing blood pressure and improving insulin sensitivity.
Maintaining healthy magnesium levels is also associated with a protective effect against depression and ADHD. Supplementation of magnesium is not very effective at reducing fat mass or cramps. Further evidence is needed to determine if magnesium supplementation can boost exercise performance, but initial results do not look promising.
The intestinal absorption of magnesium varies depending on how much magnesium the body needs, so there are not very many side-effects associated with supplementation. If there is too much magnesium, the body will only absorb as much as it needs. However, excessive doses may cause gastrointestinal distress and diarrhea.
Magnesium plays many roles in your body, so the potential mechanisms through which it may affect your mood are numerous. We’ll mention two:
Like zinc and vitamin D, magnesium may affect your mood hormonally. Low magnesium is associated with low testosterone, and low testosterone is associated with low mood in men, of course, but also in women.
Magnesium may also affect your brain directly. Preliminary evidence suggests that magnesium modulates the activity of NMDA receptors (a type of glutamate receptors found on neurons), which would explain why low levels of this mineral can result in abnormal neuronal excitations leading to anxiety.
Observational studies show that people with anxiety disorders tend to have lower levels of magnesium, and a systematic review of 18 interventions suggests that supplementation may help people who are susceptible to anxiety. The reviewers deplore, however, the poor quality of the existing evidence, and in a more recent triple-blind randomized control trial (RCT), supplemental magnesium failed to alleviate postpartum anxiety and depression.
A 2018 systematic review and meta-analysis concluded that there was little evidence for the involvement of magnesium in depression; it stressed that magnesium supplementation was associated with a decline in symptoms in uncontrolled studies, but not in placebo-controlled studies.
Magnesium deficiency isn’t unknown in the United States and United Kingdom especially in the elderly. Also, since, like zinc, magnesium is lost through sweat, athletes should take special care of their magnesium intake. Athletes participating in sports requiring weight control seem especially vulnerable to an inadequate magnesium status.
Fortunately, with just a little care, you can easily reach your Recommended Daily Intake (RDA): magnesium-rich foods are numerous and can fit all kinds of diets. And whereas high doses of supplemental magnesium can cause diarrhea and other gastrointestinal issues, “magnesium, when ingested as a naturally occurring substance in foods, has not been demonstrated to exert any adverse effects”.
If you still feel the need to supplement, at least avoid magnesium oxide: it has poor bioavailability (rats absorbed only 15% in one study, humans only 4% in another) and is more likely to cause intestinal discomfort and diarrhea.
Magnesium Rich Foods
Magnesium is widely distributed in plant and animal foods and in beverages. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources. In general, foods containing dietary fiber provide magnesium. Magnesium is also added to some breakfast cereals and other fortified foods. Some types of food processing, such as refining grains in ways that remove the nutrient-rich germ and bran, lower magnesium content substantially.
Tap, mineral, and bottled waters can also be sources of magnesium, but the amount of magnesium in water varies by source and brand (ranging from 1 mg/L to more than 120 mg/L).
Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body
*DV = Daily Value. The U.S. Food and Drug Administration (FDA) developed DVs to help consumers compare the nutrient contents of products within the context of a total diet. The DV for magnesium used for the values in table above is 400 mg for adults and children age 4 years and older. This DV, however, is changing to 420 mg as the updated Nutrition and Supplement Facts labels are implemented. The updated labels must appear on food products and dietary supplements beginning in January 2020, but they can be used now. FDA does not require food labels to list magnesium content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet.
Magnesium supplements are available in a variety of forms, including magnesium oxide, citrate, and chloride. The Supplement Facts panel on a dietary supplement label declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound.
Absorption of magnesium from different kinds of magnesium supplements varies. Forms of magnesium that dissolve well in liquid are more completely absorbed in the gut than less soluble forms. Small studies have found that magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bioavailable than magnesium oxide and magnesium sulfate. One study found that very high doses of zinc from supplements (142 mg/day) can interfere with magnesium absorption and disrupt the magnesium balance in the body.
The above information is taken from the folks at examine.com and US National Institutes Of Health