Vitamin D insufficiency in North America

Area of Science:

• Nutritional Science
• Endocrinology
• Public Health

Background:

• Vitamin D insufficiency is biochemically defined by serum 25-hydroxyvitamin D levels below 40 nmol/L.
• This condition, often without overt clinical symptoms like rickets, is increasingly recognized.
• It represents a spectrum of vitamin D deficiency, with a broader definition (< 80 nmol/L) affecting a larger population segment.

Purpose of the Study:

• To review North American studies on the prevalence of vitamin D insufficiency.
• To examine the association between vitamin D insufficiency and musculoskeletal health.
• To evaluate current vitamin D intake recommendations based on supplementation trial responses.

Main Methods:

• Review of North American epidemiological studies on vitamin D status.
• Analysis of evidence linking low serum 25-hydroxyvitamin D to bone and muscle health outcomes.
• Examination of clinical trial data on vitamin D supplementation efficacy.

Main Results:

• Vitamin D insufficiency is prevalent and linked to diminished bone and muscle health.
• A broader definition of vitamin D deficiency (serum 25-hydroxyvitamin D < 80 nmol/L) reveals widespread occurrence.
• Clinical trial responses suggest current dietary recommendations for vitamin D are inadequate.

Conclusions:

• Vitamin D insufficiency is a significant public health issue associated with poor musculoskeletal health.
• Existing recommendations for vitamin D intake may be insufficient to maintain optimal levels.
• Higher adequate intake levels for vitamin D should be considered to address widespread deficiency.