Manipulating antioxidant intake in asthma: a randomized controlled trial.

Randomized controlled trial in adults with stable asthma recruited from an asthma clinic in New South Wales, Australia. After a 14-day run-in, participants were assigned to a high-antioxidant diet, a low-antioxidant diet plus tomato extract, or a low-antioxidant diet plus placebo; 40 were allocated to the high-antioxidant diet, 33 to tomato extract, and 31 to placebo, and 79 participants completed the supplementation phase.

Tomato extract (Lyc-o-Mato) capsules provided 15 mg lycopene per capsule, taken 1 capsule 3 times daily for a total of 45 mg/day during the supplementation phase. The active supplement arm was compared with identical soybean-oil placebo capsules; a separate high-antioxidant diet arm received no supplement.

Increasing fruit and vegetable intake improved asthma outcomes, but tomato lycopene capsules did not add benefit. After 14 days, the low-antioxidant diet had lower %FEV1 and %FVC than the high-antioxidant diet, and by trial end the low-antioxidant group was 2.26 times as likely to exacerbate (95% CI 1.04, 4.91; P = 0.039). Among low-antioxidant diet participants, tomato extract and placebo showed no differences in airway or systemic inflammation or clinical outcomes, although log plasma CRP change per visit differed (0.03 [0, 0.06] vs -0.01 [-0.08, 0.06]; P = 0.010). Overall, the findings support whole-food antioxidant intake over isolated lycopene supplementation for asthma.

Single-center trial in adults with stable asthma, which limits generalizability. The active-arm sample sizes were modest, follow-up was short, and age, sex, and ethnicity were not reported in the extracted text. The supplement comparison showed little separation on most clinical outcomes despite 85% capsule compliance, limiting confidence in the null findings.