Effect of Calcium and Vitamin D on Zinc Balance in Rats

OBJECTIVES: The most pronounced consequences of nutritional calcium deficiency are observed with a parallel deficiency of vitamin D. In this regard, the creation and evaluation of foods optimally fortified with calcium and vitamin D is an important task. The aim of this study was to experimentally study the effect of different levels of alimentary calcium and vitamin D on the indices of mineral metabolism. METHODS: White growing male Wistar rats for 28 days were on semisynthetic casein rations (RCC), with different content of calcium and vitamin D: group 1 - control RCC (physiological norm of calcium and vitamin D); group 2 - RCC without calcium + 2 norms of vitamin D; group 3 - RCC with two rates of calcium (carbonate) and two rates of vitamin D; group 4 - RCC with two rates of calcium (alginate) and two rates of vitamin D and group 5 - RCC with three levels of vitamin D. The levels of calcium and zinc in serum and urine were studied. RESULTS: When the diet was fortified with calcium (carbonate or alginate) in combination with vitamin D (groups 3 and 4), there was no increase in urinary zinc excretion. Its concentration (μmol / L) was recorded at the level of 5.47 ± 1.07 (14th day) and 4.74 ± 1.03 (28th day) in animals of the 3rd group and 5.97 ± 1, 62 and 5.09 ± 1.51 in animals of the 4th group compared with similar indicators in the control: 6.27 ± 1.59 and 4.94 ± 1.08. There were no significant differences in the concentration of zinc in the blood serum in animals of these groups. In animals of the 5th group, the loss of zinc in the urine was 80% more (p < 0.05) than in the control group, and in animals of the 2nd group - by 54% more (p > 0.05). In animals of the 5th group, high concentrations of calcium in urine (mmol / l) were also noted: 1.54 ± 0.27 (p < 0.05) compared with 0.62 ± 0.05 in the control. CONCLUSIONS: The obtained result does not confirm the previously published data on the risk of zinc deficiency (due to its losses in the urine) when enriching the diet with calcium. At the same time, the isolated enrichment of the diet with vitamin D, both with calcium deficiency and with its physiological level, led to an increasing excretion of zinc in the urine during the entire observation period. Thus, vitamin D fortification in a diet low in calcium results in urinary loss of zinc and calcium. FUNDING SOURCES: No funding.