Normal Curves: Sexy Science, Serious Statistics

Bonus: Vitamin D Part 1 with commentary

16 snips
Dec 29, 2025
Dive into the vitamin D conundrum as the hosts unravel the claims of a deficiency epidemic. Discover the surprising surfer study from Hawaii that challenges assumptions about sun exposure and vitamin D levels. Explore the clash between differing medical guidelines and how arbitrary thresholds can warp our understanding of health. With a touch of statistical sleuthing, they highlight biases, conflicts of interest, and the nuances behind dietary recommendations. Get ready for a captivating discussion that questions the very data behind vitamin D health claims.
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INSIGHT

Epidemic Driven By Moving Goalposts

  • The claim of a vitamin D deficiency epidemic hinges on disputed thresholds, not clear population collapse.
  • Shifting cut points from ~10 ng/mL to 20–30 ng/mL massively inflated prevalence estimates.
ANECDOTE

Surfer Study That Defied Common Sense

  • A 2007 Hawaii surfer study recruited 93 sun-exposed surfers and reported 51% were “low” by a 30 ng/mL cutoff.
  • Using older thresholds (<10 ng/mL) those surfers would have shown zero deficiency, exposing the cutoff effect.
INSIGHT

Holick Cemented The 20/30 Cutoffs

  • Michael Holick's highly cited work (NEJM 2007) popularized the 20 and 30 ng/mL cutoffs.
  • Those thresholds were controversial and later challenged by major advisory bodies.
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