Normal bone metabolism is contingent on the presence
of vitamin D (42, 43). Low tissue levels of vitamin D
may impair the ability of bone to respond optimally to
processes in osteoarthritis and predispose to progression.
Vitamin D might also have direct effects on chondrocytes
in osteoarthritic cartilage, which have been shown to redevelop
vitamin D receptors (44).
The Framingham Study (45) reported that the risk for
progression was increased threefold for persons in the middle
and lower tertiles of both vitamin D intake (odds ratio
for lowest vs. highest tertile, 4.0 [CI, 1.4 to 11.6]) and
serum level (odds ratio, 2.9 [CI, 1.0 to 8.2]) (Table 1). On
the other hand, vitamin D was not associated with risk for
new-onset (incident) radiographic osteoarthritis. Further
longitudinal evidence of the effect of vitamin D on osteoarthritis
was recently provided by Lane and colleagues (46),
who found that high levels of vitamin D protected against
both incident and progressive hip osteoarthritis.