62 Serum concentrations of bone turnover markers and myokines in children on vegetarian and omnivorous diets

Abstract

<h3></h3> Vegetarian diets contain many beneficial properties but also carry a risk of inadequate intakes of several nutrients important for muscle and bone health. The links between muscle and bone have been recently intensively examined. Myokines, including myostatin and irisin are cytokines synthesized and released by muscle tissue. It is known that myokines affect bone metabolism, however, the mechanisms of these interactions are not fully understood. The aim of the study was to assess serum concentrations of bone turnover markers and myokines in prepubertal children on vegetarian and omnivorous diets. The study included 30 healthy children (aged 5-9 years) on a lacto-ovo-vegetarian diet and 30 children on an omnivorous diet, who were under medical and dietary control at the Institute of Mother and Child in Warsaw (Poland). Anthropometric measurement, body composition (fat mass, lean mass, bone mineral content) and dietary constituents were assessed in all studied children. Body composition was measured by dual-energy X-ray absorptiometry. Dietary assessment was performed using a nutritional software program Dieta5. Concentrations of bone metabolism markers (osteocalcin – OC, C-terminal telopeptide of collagen type I – CTX) and myokines (myostatin and irisin) were determined in serum samples by immunoenzymatic assay. Statistical analyses were done using Statistica software. This study was approved by the Ethics Committee at the Institute of Mother and Child. There were no significant differences in the anthropometric parameters: weight, height and body mass index in both studied groups. Compared with omnivores, vegetarians had similar bone mineral contents but lower (p&lt;0.05) lean mass and percentage of fat mass. Average daily dietary energy intake was similar in both studied groups, however, vegetarians had a lower intake of protein and higher intake of carbohydrates compared with omnivores (both p&lt;0.05). The serum concentration of OC was significantly lower in children on a vegetarian diet compared with omnivores (66.9±13.7 vs. 85.2±20.5 ng/mL, p&lt;0.01). Additionally, levels of CTX were higher in vegetarians than in omnivores (1.970±0.341 vs. 1.597±0.351 ng/mL, p&lt;0.01). Serum myokines concentrations did not significantly differ in both studied groups of children, but we observed slightly higher (by about 15-20%) levels of myostatin and irisin in vegetarians. Our results show that a well-planned vegetarian diet with proper dairy and egg intake does not lead to changes in bone mass in prepubertal children. However, children following a vegetarian diet had a higher rate of bone turnover and subtle changes in serum myokine levels.