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Research article2007Peer reviewedOpen access

Folates in lettuce: A pilot study

Johansson, M; Jägerstad, M; Frølich, W


Background: Leafy vegetables are good sources of folates and the food shops nowadays offer an increasing number of lettuce varieties. Objective: to obtain data on the folate content and forms in common lettuce varieties and spinach sold in the Nordic countries, and to investigate effects of different storage conditions and preparations in the consumer’s home or at lunch restaurants Design: Folate was analysed in eight different lettuce varieties and spinach using a validated HPLC method and the detected forms of folates were confirmed by a mass spectrometric detector (LC-MS) following heat extraction, deconjugation by rat serum and purification by solid phase extraction. Results: Folate content, expressed in folic acid equivalents, in the lettuce samples varied 6-fold from 30 -198 μg/100 g on fresh weight (FW) basis. The folate content was decreased with 14% after storage at 4 ºC for 8 days and with 2-40% after storage at 22 ºC for 2-4 h, depending on whether samples were stored as whole leaves, or small torn or cut pieces. LC-MS confirmed the identity of the folate forms: H4folate, 5-CH3-H4folate, 5-HCO-H4folate and 10-HCO-H4folate. Conclusion: The considerable variation of folate content between varieties of lettuce in this pilot study, one variety reaching the level found in spinach, indicates a potential to increase folate intake considerably by choice of folate-rich varieties of lettuce and storage at low temperature


leafy vegetables; folate retention; storage; folate analysis; HPLC; LC-MS

Published in

Scandinavian Journal of Food and Nutrition
2007, Volume: 51, number: 1, pages: 22-30

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      Food Science

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