Comparison of plasma and leukocyte vitamin C status between asthmatic and healthy subjects.

In a case-control study the vitamin C status of 50 adults with chronic controlled asthma was compared with that of 50 randomly selected healthy controls. Vitamin C intake was assessed by 3-day dietary recall, and plasma and leukocyte vitamin C concentrations were measured colorimetrically. A positive significant correlation was found between plasma vitamin C and dietary vitamin C intake. Plasma and leukocyte vitamin C levels were significantly lower in the asthma group. Plasma vitamin C was deficient (< 0.4 mg/dL) in significantly more patients than controls (38.0% versus 0%) and leukocyte vitamin C (< 20 microg/10(8) leukocytes) was deficient in 92.0% of asthmatics versus 8.0% of controls. A significant association was observed between duration of asthma and plasma vitamin C level.