Objective: Chlorella vulgaris is a popular food supplement in Asia and is currently marketed as a nutritional supplement. However, available scientific studies do not support its effectiveness for preventing or treating any disease in humans. Because Chlorella contains numerous nutrients, including antioxidants, it is thought to exert antioxidative functions by scavenging free radicals created by various environmental factors such as smoking. The purpose of this study was to investigate whether 6 wk of Chlorella supplementation to smokers is protective against oxidative damage in a randomized, double-blinded, placebo-controlled trial.

Methods: Fifty-two smokers, aged 20-65 y, were given 6.3g of Chlorella or placebo every day for 6 wk. Blood samples were drawn at the beginning and after the supplementation. Plasma antioxidant vitamin levels and lipid peroxidation levels were measured. As a marker of oxidative stress, lymphocyte DNA damage was measured.