The relationship between supplementation with a combination of CoQ10, vitamin C and alpha tocopherol and asthma symptoms was examined in an open, crossover, randomized study that was published in Biofactors (2005; 25(1-4): 235-40). The subjects of the study were 41 patients, between the ages of 25 and 50, with bronchial asthma. For the first four months of the study, one group received supplementation with antioxidants (vitamins E and C) and CoQ10, as well at their standard asthmatic therapy. The second group received standard asthmatic therapy alone. During the second four months of the study, the therapies were reversed for the two groups. The control group received the supplements and the original supplement group received only standard asthma therapy.

Those patients who were dependent on corticosteroids had low levels of CoQ10 in their plasma; this confirms earlier research. Taking antioxidants and CoQ10 reduced the need for corticosteroids in the subjects. The researchers concluded that supplementation with CoQ10 and antioxidants may be beneficial to patients with asthma.