The vitamin content of retail vegetables in the UK

Raw and cooked vegetables were sampled at the retail level over a two-year period and were analysed for selected vitamins. Thiamin, riboflavin, total B6 (pyridoxamine, pyridoxal and pyridoxine) and nicotinic acid were measured by HPLC, total ascorbate (ascorbic and dehydroascorbic acids) by fluorimetric determination, total folate by microbiological assay and carotenoids by spectrometry. The results were compared to values in McCance and Widdowson's The Composition of Foods and used to calculate the contribution to average daily intakes of these vitamins in the UK diet. Revised data for ascorbate, B6 and carotenoids were in good agreement with food table data, thiamin values were on average 2–3 times higher, and riboflavin and nicotinic acid values 20–50% lower. Folate results were generally higher than Food Table values for vegetables. If the revised folate values for potatoes are also taken into consideration, then the contribution that vegetables make to the average daily intake for folate may have been underestimated by about 20%. Average cooking losses ( boiling and frying ) were also in good agreement with previous data.