VITAMIN-K1 (PHYLLOQUINONE) CONTENT OF GREEN VEGETABLES - EFFECTS OF PLANT MATURATION AND GEOGRAPHICAL GROWTH LOCATION

The vitamin K1 (phylloquinone) content of five vegetables (cabbage, Swiss chard, leaf lettuce, spinach, and kale) was determined by reversed-phase high-performance liquid chromatography. The plants were grown from seed at two different locations (Boston, MA; Montreal, Canada) and analyzed with respect to maturation, soil conditions, and climatological effects. The green vegetables were found to be excellent sources of vitamin K1 (5-16 mug/g). For most vegetables except cabbage, vitamin K1 contents increased during maturation. Cabbage was found to contain 3-6 times more vitamin K1 in the outer leaves compared to the inner leaves. The vitamin K1 content of Montreal vegetables was higher than that of Boston vegetables (p < 0.05). The differences between the two locations suggest that climate, soil, and growing conditions may influence the vitamin K1 content of green vegetables. The current required dietary allowance for vitamin K can be contained in as little as a 10-g portion of a green and leafy vegetable. From a nutritional point of view, these findings have their significance when dietary vitamin K1 intake in humans is assessed.