Now that so many more people are taking vitamin D, some are asking how much vitamin D is too much. And, it’s important to note that vitamin D doses vary widely and toxicity is rare.
Here are some guidelines recommended to healthcare professionals from the evidence-based experts at The Prescriber’s Letter:
To prevent deficiency, recommend 1000 to 2000 IU/day of vitamin D for adults and 400 IU/day for infants and children.
Most people will need supplements. We don’t get much vitamin D from the sun these days due to sunscreens, staying indoors, etc.
Diet usually isn’t enough, either. Very few foods contain vitamin D … and milk only contains only 100 IU per cup.
Higher doses are needed to maintain adequate levels in some patients … or to treat a deficiency.
To treat deficiency in adults, prescribe 50,000 IU/week orally for 6 to 12 weeks then recheck levels. Tell patients it’s okay to consume milk and multivits while on this weekly vitamin D dose.
Optimal blood levels of 25-hydroxyvitamin D for bone health are at least 30 ng/mL … normal levels can reach 100 ng/mL. Increasing the dose by 1000 IU/day increases blood levels about 7 to 10 ng/mL.
Toxicity, hypercalcemia, and hyperphosphatemia usually don’t occur until vitamin D levels exceed 150 ng/mL.
Toxicity can occur with excessive doses such as 40,000 IU/day for one month in infants … and 50,000 IU/day for several months in adults.
Warn parents not to use vitamin D liquids dosed as 400 IU/DROP. Giving one dropperful or 1 mL by mistake can deliver 10,000 IU/day. FDA will force companies to provide no more than 400 IU per dropperful.
Patients sometimes ask if they can take vitamin D once a week or month for maintenance. Explain that it’s okay to take 14,000 IU once a WEEK … or 50,000 IU once a MONTH … instead of 2000 IU/day.
Encourage using D3 (cholecalciferol) since it’s more potent than D2 (ergocalciferol) … but D2 is also effective and okay to use.