Update on Magnesium

Magnesium is an important mineral in the human body, involved in essential metabolic reactions such as energy production in mitochondria, synthesis of DNA and RNA, the conduction of nerve impulses, normal heart rhythm, wound healing et al. Along with calcium, it plays an important structural role in bone,. Magnesium is at the center of the chlorophyll molecule, so it is abundant in many plant foods, such as leafy greens, beans, nuts and unrefined grains.

Low serum levels of magnesium have been found in people with asthma, diabetes, osteoporosis, and alcoholism. However, treatment with supplemental magnesium has not been uniformly found to be as helpful as a healthy lifestyle and diet. Here are some recent studies on magnesium.

Diabetes – diets with higher amounts of magnesium are associated with a significantly lower risk of Diabetes. This is based on large cohort studies over 4-20 years in length. People with the highest intake of magnesium in food were found to have up to a 20% lower risk of diabetes compared to those with the lowest intake. This association achieved significance only in people who were overweight. Some studies, but not all, show that taking magnesium supplements may help with blood sugar control.

Blood Pressure: A study from the University of Hertfordshire in England found that magnesium supplements offer small but clinically significant reductions in blood pressure. The researchers looked 22 trials involving 1,173 people, and found systolic pressure reduced by 4mmHG and diastolic by 2-3mmHG.

Brain Function: Research at the Center for Learning and Memory at Tsinghua University in Beijing found that using a new form of magnesium as an oral supplement, magnesium-L-threonate (MgT), could increase many different forms of learning and memory in both young and aged rats. The authors concluded that since many people in industrialized countries have a magnesium deficit, increasing magnesium intake might prevent or reduce cognitive decline. Similar studies from MIT, Tel Aviv University and the University of Toronto confirmed these findings, and showed that animals given the new oral magnesium compound (MgT) had an increase of synapses in the brain – connective nerve endings that carry memories in the form of electrical impulses from one part of the brain to the other. The researchers also concluded that most of today’s over-the-counter supplements don’t get into the brain effectively.

MgT as a supplement is now commercially available, and can be found on-line from several sources (such as Amazon and supplement companies like iherb). However – there are so far no real studies on its safety in humans – remember that the studies have been done on rats! At least one human study is underway. It is probably prudent to wait for validation of its safety. Discuss this with your doctor.

Taking the usual forms of supplemental magnesium (magnesium oxide, citrate, chloride) in reasonable doses (up to 350 mg daily) is safe for most people, but not everyone. People with kidney problems should confer with their doctor before taking magnesium supplements, as magnesium is excreted through the kidneys – as well as in feces. Too high a serum level can be dangerous.
Many people are taking magnesium citrate or other forms of the mineral to help them relax and sleep. Unless you have kidney disease this is probably safe, but users should be aware of the guidelines as indicated below.

The recommended dietary allowance for magnesium for adults 19-30 years old is 400 milligrams/day for men and 310 milligrams/day for women. For adults 31 and older, it is 420 milligrams/day for men and 320 milligrams/day for women. Pregnant women should get slightly more – from food and prenatal vitamin-mineral supplements. When women take calcium supplements, it is advisable to take half as much magnesium as calcium – for example 500 mg of calcium with 250 mg of magnesium.

In 2011, the Food and Drug Administration issued a safety announcement that long-term use - longer than one year - of prescription proton pump inhibitor (PPI) drugs (such as Nexium and Prilosec) may cause low serum magnesium levels. Treatment usually involves magnesium supplements, but in about 25% of cases the PPI has to be discontinued. Over the counter doses of these same drugs are lower, and their use is advised for no more than 15 days up to 3 times a year.

Fortunately, magnesium is found in some wonderful foods easily available, such as leafy greens. beans, nuts and whole grains. Fresh green beans are in season!
Sadja Greenwood MD, MPH – past issues on this blog