Antioxidant activity and profiles of common vegetables in Singapore

Abstract

Sixty-six types of vegetables commonly consumed in Singapore were analysed for their hydrophilic oxygen radical absorbance capacity (H-ORAC), total phenolic content (TPC), ascorbic acid (AA) and various lipophilic antioxidants. A single batch analysis of each vegetable showed that antioxidant composition and concentration varied widely across different vegetables. The vegetables with intense colours typically have high H-ORAC, TPC, AA, and carotenoid contents. Vegetables unique to the Asian market such as matrimony vine (Lycium chinense Miller), coriander, Chinese kale, water spinach and red chilli were consistently ranked high in H-ORAC, TPC, carotenoids and vitamin E levels. Based on consumption data, Chinese Singaporeans appear to have a higher intake of lutein, zeaxanthin, β-carotene, and tocopherols compared to the US population. Overall findings suggest that dark green leafy and brightly-coloured vegetables tend to contain high antioxidants. Our data are useful reference and substantiate many public health agencies’ recommendation to consume more vegetables, particularly the dark green leafy and brightly-coloured varieties.