Determination of Fat-Soluble Vitamins in Human Plasma, Breast Milk and Food Samples: Application in Nutrition Survey for Establishment of "Dietary Reference Intakes for Japanese"

Abstract

Dietary habits are an important risk factor for lifestyle-related diseases. To carry out a nutrition survey of fat-soluble vitamins, we developed determination methods of fat-soluble vitamins using liquid chromatography-atmospheric pressure chemical ionization/tandem mass spectrometry or high-performance liquid chromatography with fluorescence detection. In these methods, stable isotope-labeled compounds or vitamin K analogs with a saturated side-chain were used as internal standards. These methods have high sensitivity and sufficient accuracy, and we applied them in a nutrition survey about the status of fat-soluble vitamins in Japanese women. Plasma concentrations of 25-hydroxyvitamin D3 [25(OH)D3] and 25-hydroxyvitamin D2 [25(OH)D2] in healthy postmenopausal women (n=98) were 20.5±7.9 and 0.4±1.4 ng/ml, respectively. A significant negative correlation in plasma levels between 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone was observed. For vitamin K homologs, plasma levels of phylloquinone (PK), menaquinone-4 (MK-4) and menaquinone-7 (MK-7) in Japanese women of various ages (n=1409) were 1.03±0.90, 0.12±0.28 and 6.71±13.6 ng/ml, respectively. The mean total vitamin K intake of Japanese young women was about 230 μg/day, and 94% of participants met the Adequate Intake of vitamin K for women aged 18-29 years in Japan, 60 μg/day. Moreover, we determined fat-soluble vitamins in breast milk collected from Japanese lactating women and revealed that the contents of all-trans-retinol, vitamin D3, 25(OH)D3, α-tocopherol, PK and MK-4 in breast milk were 0.39±0.14 μg/ml, 0.10±0.15 ng/ml, 0.08±0.04 ng/ml, 3.96±1.84 μg/ml, 3.56±2.19 and 1.77±0.68 ng/ml, respectively.