Seventeen subjects were randomly assigned in a double-blind fashion to receive a broad-based antioxidants supplement containing beta-carotene , ascorbic acid , d-alpha-tocopherol-succinate , N-acetylcysteine , riboflavin , zinc , and selenium ( antioxidant capsule group -LSB- AO group -RSB- ) , or a combination of alpha-ketoglutaric acid ( - KG ) and @-hydroxymethylfurfural ( @-HMF ; CYL concentrate supplementation group -LSB- CS group -RSB- ) , or placebo ( PL group ) .