Do you need more vitamin D3?
While higher body fat levels can predict vitamin D deficiency, checking your blood levels of D3 is the only way to determine your actual vitamin D status. Optimal blood levels of D3 range are thought to be 32 ng/mL (80 nmol/L). Anything lower than 30 ng/mL (75 nmol/L) indicates deficiency; levels greater than 150 ng/mL (375 nmol/L) indicate toxicity.
If your blood levels of D3 are below 30 ng/mL (75 nmol/L), ask with your physician about taking 2,000 IU of vitamin D3 daily. Although recent recommendations suggest that in the absence of sun exposure, adults should ingest 1,000 IU of vitamin D3 per day, vitamin D3 supplements providing 2,000 IU/day may be more appropriate for heavier individuals.
Is taking 2,000 IU/day of vitamin D safe?
Currently, the tolerable upper limit for vitamin D set by the Institute of Medicine is 2,000 IU per day. However, many of the experts responsible for setting this limit now believe it needs to be substantially increased. Research published in the January 2007 American Journal of Clinical Nutrition reviewed dozens of vitamin D toxicity studies, including some in which volunteers took 100,000 IU a day without any adverse effects!
The authors of the vitamin D toxicity review concluded that the upper limit for daily intake of vitamin D could safely be set at 10,000 IU. This is not surprising when one realizes that just 10-15 minutes whole-body exposure to peak summer sun will generate and release up to 20,000 IU vitamin D3 into the circulation.
