British researchers found people with asthma may require less inhaled medication if they also take vitamin C, according to the journal Respiratory Medicine (2006;100:174-9). Inhaled corticosteroids are the most commonly prescribed medications for asthma, but long-term use is associated with a number of undesirable side effects, such as cataracts, bone loss, and immune-system suppression.
In a clever two-part study, the researchers first determined whether vitamin C [1] (1 gram per day for 16 weeks) or magnesium (450 mg per day for 16 weeks) could control asthma symptoms better than placebo in 92 adults with asthma. For good reasons, it was not expected to result in much improvement.
The benefits of supplements are likely to be small and difficult to detect with this study design because the vast majority of people with asthma already control their symptoms using drugs. Thus, there was little opportunity for people in this study to improve as long as they remained on the drugs, which they did at normal doses throughout this part of the study.
As expected, vitamin C and magnesium failed to improve symptom control significantly over baseline levels. Since previous research suggested these nutrients could offer a benefit, the authors designed a second part to the study to discover whether any beneficial effects of the supplements might have been masked by the drugs. To explore this, participants continued their supplement (vitamin C, magnesium, or placebo) while undergoing a ten-week, staged reduction in their corticosteroid medication.
This time vitamin C was found to have a modest effect. Asthma sufferers who took vitamin C were able to reduce their intake of inhaled corticosteroids without any loss of symptom control. This is actually quite important because the side effects of corticosteroid drugs increase when higher doses are used. So reducing daily intake by even a small amount could prevent some adverse effects. Magnesium demonstrated no effect in this study.
The adrenal glands produce the body’s own corticosteroid hormones. Research suggests that the adrenals require vitamin C to make these hormones. It therefore makes sense that taking a vitamin C supplement supports the body’s own production of adrenal corticosteroids, seemingly thereby reducing the amount of hormone needed in drug form.
People taking asthma medications should not abruptly discontinue their steroid medications, even if they are taking vitamin C as rapid withdrawal from steroid medications can cause serious health problems. Discuss the situation with your prescribing doctor to arrange a safe and monitored reduction in the amount of any prescription medication.