Deficient dietary vitamin K intake among elderly nursing home residents in Hong Kong

There is strong evidence supporting the importance of vitamin K in bone health and the aetiological role of vitamin K deficiency in osteoporosis. In view of the common occurrence of osteoporosis among older subjects in Hong Kong, we have studied the dietary vitamin K intakes in 100 residents of a nursing home (43 men, 57 women; median age 81.0 years) and 88 free-living subjects attending a day care centre (13 men, 75 women; median age 71.5 years). The subjects were interviewed and the average vitamin K intake in the preceding week was estimated, using a diet recall questionnaire modified from our previous surveys of dietary patterns in local Chinese people. The median vitamin K intake was much lower in nursing home residents than in free-living subjects (4.50 vs 488.09 microg/day or 0.13 vs 8.74 microg/kg/day, P<0.001). An intake that was below the recommended daily intake was far more common among nursing home residents (86.0 vs 11.4%, P < 0.001). Among nursing home residents, there was a negative correlation between age and vitamin K intake (r = -0.217, P = 0.030), but there was a positive correlation between body weight and vitamin K intake (r = 0.244, P = 0.015). No such relationship was seen among free-living subjects. Elderly nursing home residents in this study generally had a poor dietary vitamin K intake and might therefore be predisposed to osteoporosis. The importance of green leafy vegetables as a rich source of vitamin K should be emphasised.