Friday, January 22, 2010

Vitamin K


Effects of vitamin K on the morphometric and material properties of bone in the tibiae of growing rats.

"Suboptimal vitamin K nutriture is evident during rapid growth. We aimed to determine whether vitamin K(2) (menaquinone-4 [MK-4]) supplementation is beneficial to bone structure and intrinsic bone tissue properties in growing rats. Male Wistar rats (5 weeks old) were assigned to either a control diet or an MK-4-supplemented diet (22 mg d(-1) kg(-1) body weight). After a 9-week feeding period, we determined the serum concentration ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin and the urinary deoxypyridinoline level. All rats were then euthanized, and their tibiae were analyzed. Neither body weight nor tibia length differed significantly between the 2 groups. Dietary MK-4 supplementation decreased the ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin but did not affect deoxypyridinoline, indicating a positive effect on bone formation but not bone resorption. Trabecular volume fraction and thickness were increased by MK-4. Neither the cortical pore structure nor mineralization was affected by MK-4. On the other hand, MK-4 increased mineral crystallinity, collagen maturity, and hardness in both the anterior and posterior cortices."

Tibia length was 35.6 for the K supplement group and 35.5 for control.

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