[Efficiency of vitamin D deficit correction depending on rats' supply with B vitamins].

Despite the presence of combined deficiency of vitamins D and group B among the population of Russia, the intake of cholecalciferol is often recommended without correcting the supply with B group vitamins, which are involved in ensuring the biological functions of vitamin D. The aim of the study was to compare the effectiveness of vitamin D deficit correction by replenishing its content in the diet to an adequate level without eliminating the deficit of B vitamins and by restoring vitamin D level in combination with B vitamins. Material and methods. The experiment was carried out on male Wistar rats (n=33) with an initial body weight of 69.5±0.8 g. Combined deficit of vitamins D and B group in rats (n=24) was caused by a 5-fold decrease in their content in the vitamin mixture of a semi-synthetic diet for 23 days. Over the next 7 days, in order to correct vitamin deficiency, 12 rats (group «-B+D») were fed a diet, replenished up to 100% for vitamin D with continued deficiency of B group vitamins, and 12 rats (group «+B+D») were fed a diet replenished for all missing vitamins. Animals of the control group (n=9) received a full semi-synthetic diet during the entire experiment. The concentration of vitamins A and E in blood plasma and lyophilized liver and whole brain was determined by HPLC, vitamins B1 and B2 in the liver, brain and urine, riboflavin in plasma and 4-pyridoxic acid in urine - by fluorimetric methods, 25(OH)D in blood plasma was determined by ELISA. The content of calcium, magnesium, iron, manganese, zinc and copper in freeze-dried liver and brain was determined by atomic absorption method, biochemical parameters of blood and urine were determined using a biochemical analyzer. Results. The only vitamin D addition to the feed with a persisting deficiency of B vitamins did not restore the concentration of 25(OH)D and osteocalcin to the level in control animals sufficiently provided with all vitamins. In animals of the "-B+D" group, 25(OH)D plasma level was reduced by 17.3% (p<0.10), osteocalcin - by 11.7% (p<0.05), the activity of aspartate aminotransferase was 1.5 fold less, alanine aminotransferase - 2.3 fold (p<0.05), lactate dehydrogenase - by 14.9% (p<0.10), while the concentration of iron exceeded 2.7 times, glucose - by 15.0%, calcium - by 8.0%, creatinine - by 8.7% (p<0.05), urea - by 32.1%, direct bilirubin - by 24.2% (p<0.10 ) compared with corresponding indicator in rats of the control group. The level of cholesterol and HDL cholesterol was 14.7% and 15.9% higher (p<0.10) than in animals of the «+B+D» group. Conclusions. Deficiency of B vitamins inhibits the restoration of adequate supply with vitamin D. In the presence of a lack of B vitamins in rats, vitamin D deficit and its consequences cannot be completely eliminated. Adequate supply with vitamins D and B group are synergistic factors in maintaining the level of glucose, cholesterol in blood plasma and other diagnostically significant parameters.