Vitamin D: health panacea or false prophet?

Area of Science:

• Nutritional Science
• Endocrinology
• Public Health

Background:

• Vitamin D deficiency is a prevalent global health issue, comparable to vitamin A deficiency.
• Extensive research in the 21st century highlights vitamin D's broad physiological roles.
• Adequate vitamin D status is associated with reduced risk for numerous chronic diseases and conditions.

Purpose of the Study:

• To critically evaluate the current understanding of vitamin D's role in health and disease.
• To examine the limitations of using serum 25-hydroxyvitamin D (25-OHD(3)) for diagnosing vitamin D status.
• To question the universal recommendation for increasing vitamin D intake due to potential risks.

Main Methods:

• Review of scientific literature on vitamin D status, deficiency, and supplementation.
• Analysis of the relationship between vitamin D levels and various health outcomes.
• Investigation into the mechanisms of vitamin D action and potential toxicity.

Main Results:

• Vitamin D deficiency is linked to numerous health issues, while deficiency in pregnancy may affect offspring.
• Evidence suggests localized tissue vitamin D intoxication can occur at lower serum levels than appreciated.
• Serum 25-OHD(3) levels are poorly responsive to intake, and excessive intake may disrupt phosphate homeostasis via FGF23 and Klotho.

Conclusions:

• Current reliance on serum 25-OHD(3) may not fully capture an individual's vitamin D status or risks.
• Excessive vitamin D intake can have detrimental health consequences, including interference with phosphate regulation.
• A more cautious approach to universal vitamin D supplementation recommendations is warranted.