Contribution of a liquid chromatographic method to evaluate if Portuguese vegetables are a good source of vitamin C?

Santos, I.C.; Albuquerque, T.G.; Silva, M.A.; Costa, H.S.

http://hdl.handle.net/10400.18/5322

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Abstract(s)

Vitamin C is a water-soluble vitamin which cannot be synthesized by the human body. It is a highly thermolabile vitamin and it has two biologically active forms, L ascorbic acid and its oxidation product, dehydroascorbic acid. This vitamin is naturally present in various vegetables and fruits, and is an excellent antioxidant to scavenge free radicals and to prevent oxidative stress. The daily reference intake established for adults in Regulation (EU) No 1169/2016 for this vitamin is 80 mg/day. The aim of this study was to determine the vitamin C content in different vegetables varieties and to evaluate their contribution to the daily reference intake of vitamin C for adults. In 2016, 11 types of raw vegetables (beetroot, broccoli, carrot, courgette, cucumber, ginger, iceberg lettuce, pumpkin, purple cabbage, spinach and tomato) were acquired in commercial areas in Lisbon. Samples were manually separated between edible portion and non-edible portion, and their vitamin C content (L-ascorbic acid and dehydroascorbic acid) was determined by a previously validated HPLC method. The nutritional contribution was calculated using the daily reference intake defined in Regulation (EU) No 1169/2011. The vitamin C content in the analysed samples ranged from 0.259 ± 0.04 to 64.5 ± 1.5 mg/100 g of edible portion for beetroot and broccoli, respectively. According to the results obtained, 100 g of raw broccoli contributes approximately with 81% of the daily intake for vitamin C, whereas the same amount of beetroot only contributes with approximately 0.3%. Considering the vitamin C content per 1 serving portion of vegetables (180 g of raw vegetables), it was found that broccoli was the only sample analysed that could exceed the daily reference intake (80 mg/day). Comparing the analytical content of vitamin C in the analysed vegetables with the daily reference intake established for this vitamin, we can conclude that for the majority of the vegetables it is necessary to consume more than one portion to reach the recommended value. However, it is necessary take into account that the vitamin C of these foods can be affected by many factors, such as climate, soil, and harvest, storage and processing methods.