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Nutritional
Vitamin D
25-hydroxyvitamin D — a steroid hormone essential for bone health, immune regulation, and mood.
Optimal Range
40-60 ng/mL (optimal) · 30-100 ng/mL (sufficient)
Why It Matters
Vitamin D deficiency affects an estimated 40-50% of adults worldwide and is linked to immune dysfunction, osteoporosis, depression, and increased all-cause mortality. Supplementation is one of the most cost-effective longevity interventions.