In female elite athletes strenuous exercise may result in hypoestrogenism and amenorrhoea.
As a consequence a low peak bone mass and rapid bone loss are often seen in relatively
young athletes. In postmenopausal women, increased intake of vitamin K may result
in an increase of serum markers for bone formation, a decrease of urinary markers
for bone resorption, and a decrease in urinary calcium loss. In the present paper
we report an intervention study among eight female athletes, four of whom had been
amenorrhoeic for more than one year, whereas the others had been using oral contraceptives.
All participants received vitamin K supplementation (10 mg/day) during one month,
and various bone markers were measured before and after treatment. At baseline the
athletes not using oral contraceptives were biochemically vitamin K-deficient as deduced
from the calcium binding capacity of the circulating bone protein osteocalcin. In
all subjects increased vitamin K was associated with an increased calcium-binding
capacity of osteocalcin. In the low-estrogen group vitamin K supplementation induced
a 15 - 20 % increase of bone formation markers and a parallel 20 - 25 % decrease of
bone resorption markers. This shift is suggestive for an improved balance between
bone formation and resorption.
Key words
Phylloquinone - bone mass - bone loss - calcium metabolism - osteoporosis - exercise
