Recent epidemiological studies suggested that serum 25-hydroxyvitamin D [25(OH)D] concentration ≥75 nmol/L appeared to be optimal for preventing cardiometabolic diseases and improving bone health. To achieve this goal, a daily intake of 1000 IU or equivalent amount from other sources, is needed, which is twice as much as the RDA recommended by Chinese Nutrition Society. Meanwhile,epidemiological evidences show that large proportions of Chinese may suffer vitamin D insufficiency or deficiency whereas the current RDA in China might be too low to provide adequate vitamin D for people's health.~In order to fill up this gap, therefore, it is essential to determine the dose-response between the doses of vitamin D3 supplements and raised serum levels of 25(OH)D and also the dose of vitamin D3 required to achieve circulating 25(OH)D ≥ 75 nmol/L.Ultimately, the current study will provide important evidence for establishing optimal vitamin D requirement for Chinese people
To determine the dose-response between the doses of vitamin D3 supplements and raised serum levels of 25(OH)D and also the dose of vitamin D3 required to achieve circulating 25(OH)D ≥ 75 nmol/L;