Low intakes of certain vitamins/minerals, such as zinc, vitamin C, manganese and magnesium, can make people as much as five times more likely to develop asthma (Thorax, 1997; 52: 166-70). While general levels of nutrition need to be good to keep asthma at bay, supplementing with certain nutrients is considered crucial.

* Magnesium levels are chronically low in asthmatics, and supplementation (400-800 mg/day) can help relax the bronchial tubes and oesophagus (Magnesium Res, 1995; 8: 403-5).

* Vitamins B6 and B12, which asthmatics are most likely to be deficient in (J Nutr Med, 1990; 1: 277- 82). Many asthmatics are also sensitive to sulphite preservatives in foods such as potato chips, fish, fruit juices and jellies; B12 can reduce sulphite sensitivity (Res Inst Scripps Clin Sci Rep, 1982; 39: 57-8). Take 25-50 mg/day as part of a B-complex.

* Vitamin A and beta-carotene (4000 IU of both), vitamin C (1000-3000 mg) and vitamin E (400- 600 IU), which are antioxidants, aid lung functioning (Am J Epidemiol, 2002; 155: 463-71). Vitamin C is a potent antihistamine with no side-effects and should be taken with bioflavonoids such as quercetin, which has been found to inhibit the release of inflammatory compounds (J Allergy Clin Immunol, 1984; 73: 819-23). Take 500 mg twice a day.

* Glutathione (500-1000 mg) and other sulphur-containing nutrients, N-acetylcysteine, or NAC (500-800 mg), methyl-sulphonyl-methane, or MSM (500-1000 mg) and lipoic acid (200-500 mg) are also antioxidants and may be helpful. NAC, for instance, can increase glutathione levels and thin bronchial mucus (Chest, 1997; 112: 164-72).