Vitamin D has been traditionally seen to be mainly involved in the regulation of bone homeostasis. However,
vitamin D has also been clinically linked to various diseases, including
metabolic syndrome. The aim of this study was to examine the effect of low and high doses of a
vitamin D supplement on the serum levels of 25(
OH)D3 and
insulin resistance. A total of 120 females were recruited in this study and supplemented weekly with 25,000 IU
vitamin D or 50,000 IU
vitamin D for three months. Anthropometric measurements were taken at the beginning of the study. Blood samples were collected at the beginning of the study to determine the baseline of the clinical variables and collected again after three months.
Insulin resistance was measured using Homeostatic Model Assessment for
Insulin Resistance (HOMA-IR). After
vitamin D supplementation, a non-significant increase was observed in the serum levels of 25(
OH)D3 in the group treated with a low dose of
vitamin D (LDVD) and a highly significant increase was seen in the group treated with a high dose of
vitamin D (HDVD). In the group treated with a higher dose (HDVD), a significant improvement in
insulin sensitivity was observed. The high dose of
vitamin D (50,000 IU) supplementation was more effective in both correcting the blood levels of
vitamin D and improving the sensitivity of
insulin.