Folate composition of 10 types of mushrooms determined by liquid chromatography-mass spectrometry

White button, crimini, shiitake, maitake, enoki, oyster, chanterelle, morel, portabella, and uv-treated portabella mushrooms were sampled from U.S. retail outlets and major producers. Folate [5-methyltetrahydrofolate (5-CH₃-H₄folate), 10-formyl folate (10-HCO-folate), 5-formyltetrahydrofolate (5-HCO-H₄folate)] was analysed using a validated LC-MS method in four composites of each product, including an in-house mushroom control composite and a reference material (BCR 485 Lyophilised Mixed Vegetables). Chanterelle and morel had the lowest total folate (2-6μg/100g), oyster had the highest (mean, 44.2μg/100g); other types contained 12.4μg/100g (shiitake) to 29.8μg/100g (vitamin D-enhanced portabella). Enoki and oyster had almost exclusively 5-CH₃-H₄folate. Morel and chanterelle contained predominately formyl folates. Other species had similar amounts of 5-CH₃-H₄folate and formyl folates. Enoki, oyster, and shiitake, unlike all others, had low to non-detectable 10-HCO-folate (<1μg/100g). These precise data on the composition of folate vitamers in different types of mushrooms will facilitate assessment of the dietary contribution of naturally occurring folate.