The present study is part of a project titled 'Magnesium in asthma and chronic obstructive pulmonary disease'. The hypothesis of the main project is that a daily magnesium supplement will benefit patients with asthma and chronic obstructive pulmonary disease.

The aim of this part of the project is to reveal possible beneficial effects of daily magnesium supplement for severe asthmatics, refractory to conventional treatment.

Inclusion Criteria:

• severe asthmatics, refractory to conventional treatment, including systemic steroid treatment; symptoms must be annual.

Exclusion Criteria:

• Se-Mg > 2,00 mmol/L,
• smoking cessation less than 1 year prior to study start,
• major changes in eating habits within three months prior to study start and during the study period of approximately one year,
• various conditions (e.g. gastrointestinal disease, kidney disease, pregnancy/lactation) that may affect the study results.