RESEARCH - Vitamin K levels may be too low to support bone health in early menopause

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Vitamin K Levels May Be Too Low to Support Bone Health in Early Menopause

NEW YORK (Reuters Health) Oct 05 - As estrogen levels drop in early

menopause, vitamin K function in bone is impaired before any actual bone

loss is seen, new research shows.

" Our study suggests that the generally accepted level of vitamin K in

healthy women is inadequate to maintain bone health just at the onset of

menopause, " lead author Dr. Jane L. Lukacs, from the University of Michigan

at Ann Arbor, said in a statement.

The findings, which appear in the September/October issue of Menopause,

indicate that the percentage of undercarboxylated osteocalcin (%ucOC) is a

bone marker specific for early postmenopause in healthy women.

Binding of osteocalcin to calcium is necessary for normal bone formation.

However, only the carboxylated form of the protein, which is dependent on

adequate vitamin K levels, binds to calcium. Thus, without enough vitamin K,

bone formation can be impaired.

The current study involved a comparison of various hormone and vitamin

K-related biomarkers in 19 cycling young women (20 to 30 years), 19 cycling

older women (40 to 52 years) and in 21 women in early postmenopause (40 to

52 years).

The estradiol and vitamin status in cycling older women was similar to that

of their younger peers, but they did have lower osteocalcin and bone mineral

density at the total hip.

BMD was comparable at all sites in the two older groups, but osteocalcin was

elevated in the early postmenopausal group, indicating increased bone

turnover. Circulating vitamin K levels were highest in early postmenopausal

subjects, yet they also had the highest %ucOC.

" These data demonstrate an early menopause-specific adverse association with

the carboxylation status of osteocalcin, suggesting that the levels of

vitamin K common in healthy women and presumed to be adequate to maintain

normal clotting mechanisms are inadequate to maintain postmenopausal bone

health, " the researchers conclude.

Menopause 2006;13:799-808.

http://services.medscape.com/viewarticle/545607

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