Magnesium benefits asthmatics

January 8, 2007

Almost everyone gets far less magnesium in their diet than people got in the past. It seems that this greatly worsens life for asthmatics. But the problem has hardly been investigated.

One has to take magnesium seriously. It is a vital mineral, but many people get far less than the 3-400 milligrams a day that are considered adequate. Before the industrialization, we got an average of approx. 500 mg a day (some have said 1,000). Today, many get less than 250.

Several reports in recent years have linked magnesium deficiency to asthma and allergies. In 1994, for example, an English study showed that the more magnesium asthmatics got, the better their lung function. Those who received 500 mg a day had 25% better lung function than those who received 400 – judged by the amount of air you can exhale in one second.

Asthma was not very common in the past. Today, it is a fearsome widespread disease. Approx. every tenth Danish school child has asthma. In Aberdeen and Philadelphia, every fourth child at the age of eight has it. The frequency in Denmark has more than tripled since the 1970s, and no one has any reasonable explanation. What if magnesium deficiency is part of the cause?

During an asthma attack, the bronchi contract so that the air can neither get out nor in – especially not out. But as early as 1912, the famous physician Trendelenburg – it was he who suggested that you should have your legs up in the air if the blood pressure drops – showed that magnesium has the opposite effect. It dilates the bronchi. It was on cows, but in 1936 it was also detected on humans.

Still, only two randomized studies have actually been made to investigate the effect on asthma. One (from 1997) showed that magnesium reduces symptoms. The second (from 2003) showed nothing, which was probably due to the patients receiving so much medication that there was nothing to improve.

Less allergy
Now a team of Brazilian doctors has made a third attempt. They studied 37 children and adolescents (7-19 years) with persistent moderate asthma and allergies. All received medical treatment in the form of an asthma spray with a bronchodilator in addition to adrenal cortex hormone. In addition, they had an acute-acting spray for use in aggravation.

In 18 of the children, this treatment was supplemented with 300 mg of magnesium daily for two months. The rest received placebo (“calcium pills”). Who got what, was decided by secret drawing of lots.

Magnesium helped. Those who received magnesium had significantly fewer days of asthma exacerbation during the two months (12 and 17, respectively). Despite this, they also had significantly fewer days in which to resort to the acute-acting spray (7 and 12, respectively). Although the experiment was small, the differences were statistically extremely reliable. In addition, those who were treated responded far less to the traditional skin prick tests used to examine for allergies. They actually became less allergic! Finally, one could directly measure that their bronchial mucosa was far less irritable.

The conclusion is obvious: Trendelenburg’s old discovery holds water with great certainty. But magnesium is a very cheap mineral (a prolonged-release tablet with 360 mg costs a little over a penny), which no one can patent. Who will pay for further research?

Niels Hertz, MD


1. Gontijo-Amaral C et al. Oral magnesium supplementation in asthmatic children: A double-blind placebo controlled trial. European Journal of Clinical Nutrition 2007: 61:54-60.
2. Britton J et al. Dietary magnesium, lung function, wheezing, and airway hyperreactivity in a random adult population. Lancet 1994;344:357-62