[Effect of vitamin D supplementation on serum 25-hydroxyvitamin D and bone turnover markers concentrations in vegetarian children].

PURPOSE

Vitamin D plays a key role in bone mineralization by regulating calcium and phosphate metabolism. Deficiency of this vitamin may lead to disturbances in bone metabolism as well as to osteopenia and osteoporosis.

AIM

1. Assessment of daily intake of calcium and vitamin D in children on vegetarian diet. 2. Measurement of serum 25-hydroxyvitamin D and biochemical bone turnover markers levels in vegetarian children supplemented with calcium and vitamin D, before and after the intervention.

MATERIAL AND METHODS

We examined 35 prepubertal children on vegetarian diet who were divided into two groups: group A (without supplementation) and group B in which the children received daily 400 IU vitamin D3 and 500 mg calcium. Total serum calcium, phosphate, 25-hydroxyvitamin D and bone turnover markers were measured at start and end of the intervention.

RESULTS

Concentration of calcium and phosphate in serum of all tested children were within physiological range. The mean value of 25-hydroxyvitamin D at start of supplementation was low in both the vitamin D-treated group and in the controls (about 19 ng/ml). After 4-months supplementation, the vitamin D level was significantly higher in the vitamin D-treated group (38.3+/-8.5 ng/ml) than in the control group (13.7+/-5.3 ng/ml) (p<0.001). No statistically significant differences in bone formation (osteocalcin) and resorption (carboxy-terminal telopeptide of type I collagen, isoenzyme 5b of tartrate-resistant acid phosphatase) markers were observed.

CONCLUSIONS

The presented results indicate that in vegetarian children the daily dietary intake of vitamin D in the winter months is not sufficient to maintain adequate serum vitamin D concentration. Vitamin D daily supplementation increases vitamin D concentration in these individuals to the required levels.