剛發現加拿大政府關於補充維生素D的推薦文章：

文章的倒數第二部分是：Did the IOM（The U.S. Institute of Medicine） report make recommendations with respect to serum vitamin D levels?

Serum concentration of 25-hydroxy-vitamin-D (25(OH)D) is the best indicator of vitamin D status.  It reflects total vitamin D input - from food, supplements, and sun exposure.

There is considerable discussion surrounding the serum concentrations of 25(OH)D associated with optimal health, and cut points have not been developed by a scientific consensus process.

However, the IOM expert committee stated that its review of the data suggests that, relative to bone health:

• People are at risk of vitamin D deficiency (rickets or osteomalacia) at serum 25(OH)D concentrations <30 nmol/L. Some are potentially at risk for inadequacy at levels ranging from 30–50 nmol/L.
• Practically all people are sufficient at levels ≥50 nmol/L（≥20 ng/mL）
• There may be reason for concern at serum concentrations >125 nmol/L（>50ng/ml)

The IOM expert committee encouraged the development of evidence-based cut points for serum vitamin D measures relative to deficiency as well as excess.

https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/vitamins-minerals/vitamin-calcium-updated-dietary-reference-intakes-nutrition.html