Only four groups are told to take it without a blood test
The Endocrine Society's 2024 guideline suggests taking vitamin D without testing only for ages 1 to 18, adults over 75, pregnancy, and high-risk prediabetes.
What the study found
The guideline narrows empiric vitamin D to four groups
The Endocrine Society's 2024 guideline suggests taking vitamin D without testing only for ages 1 to 18, adults over 75, pregnancy, and high-risk prediabetes. For healthy adults under 75 it suggests against exceeding the standard reference intake of 600 to 800 international units a day.
The caveat · Over-75 advice: a very small effect
The over-75 recommendation rests on a very small reduction in deaths, graded as high certainty but never translated into a number of lives. Most of the guideline's positions are worded as suggestions rather than recommendations, the wording used when certainty is low. The trials behind it used widely varying doses and often let participants keep taking their own vitamin D, so the right dose is left unresolved.