Definitions of vitamin D status (based on blood test results):
- Vitamin D deficiency <50nmol/L
- Vitamin D insufficiency = 50-75nmol/L
- Vitamin D sufficiency >75nmol/L
- Multiple studies cite optimal levels at >100nmol/L
For those people with vitamin D in the healthy range, a supplement containing 1000IU daily may be sufficient to maintain healthy levels. However, 73% of Australians have vitamin D levels less than 75nmol/L and only 10% of Americans have levels >100nmol/L. Therefore, many people may require higher levels of vitamin D supplementation to achieve target levels.
Toxicity from excessive oral intake of vitamin D is possible, however, no evidence of vitamin D toxicity has been shown with doses of up to 4000IU daily and signs and symptoms of toxicity are unlikely at daily intakes below 10,000IU. Currently, the TGA recommends a daily intake of no more than 1000 IU for the general population. However, it may be optimal to take a vitamin D supplement in the range of 1000-4000IU per day depending on your vitamin D status. To know for sure, we recommend you talk to your GP about your optimal daily dosing needs.
1. Daly R, Gagnon C, Lu Z, Magliano D, Dunstan D, Sikaris K et al. Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study. Clinical Endocrinology [Internet]. 2012;77(1):26-35. Available from: https://pubmed.ncbi.nlm.nih.gov/22168576/
2. Office of Dietary Supplements - Vitamin D [Internet]. Ods.od.nih.gov. 2021 [cited 1 April 2021]. Available from: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/