Vitamin D
The sunshine vitamin most people are missing.
~42% of American adults are vitamin D deficient (below 20 ng/mL)
Why it matters for longevity
Vitamin D regulates calcium absorption, supports immune function, and modulates gene expression in nearly every tissue. Low vitamin D status is associated with increased all-cause mortality, higher cancer risk, and accelerated bone loss. A meta-analysis of 52 trials found that vitamin D supplementation reduced all-cause mortality by about 6%.
How much you need
600 IU (15mcg) for adults 19-70, 800 IU (20mcg) for adults over 70
Many longevity researchers target serum levels of 40-60 ng/mL, which often requires 2,000-4,000 IU daily.
Signs you might be low
- Fatigue and low energy
- Frequent illness or infections
- Bone pain or muscle weakness
- Low mood, especially in winter
Best food sources
Key research
Autier P, Gandini S (2007). Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Archives of Internal Medicine, 167(16), 1730-1737.
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