by owenversteeg | 2025-09-07 19:03:23+00:00
Few interesting statistics for people:

1. Only 12% of US adults have vitamin D levels in the recommended range [0] and while vitamin D levels are strongly associated with nearly every marker of health, supplementing vitamin D does not improve health [3]

2. Vitamin D levels are strongly correlated with overall health, quality of life, and decreased mortality (incl. cancer mortality, CVD mortality, et cetera [5.]) This association is quite robust. "Lower 25(OH)D concentrations were also associated with increased all-cause mortality among participants who reported being in good to excellent health" [5] When you adjust for age/sex/race/smoking, a lot of health indicators (such as BMI!) fall apart; this is why we now consider waist to hip ratios as better predictors [6, 7.] Vitamin D levels, however, remain a robust predictor of health, even adjusted for age/sex/race/health factors [5.]

3. Annual deaths from melanoma, 8430; median US age at death from melanoma, 72 [1] (just a few years off the median US age at death from any cause!)

4. Age-adjusted melanoma deaths by race per 100k: flat since the 80s [2.] "By race" is important here because different racial groups have wildly differing melanoma risk, and the racial makeup of the US is not constant with time.

In other words, in terms of risk-reward, there is no question: the median person should trade off even a large increase in melanoma death risk for a small increase in vitamin D levels. Can you, or is that a false argument?

Bit of background: "Terrestrial ultraviolet radiation (UVR) is the main determinant of vitamin D status. Stratospheric ozone absorbs all solar UVC (100–280 nm), attenuates UVB (280–315 nm) but not UVA (315–400 nm). The sun's height determines the UVR pathlength through the ozone layer. Thus, UVB intensity (irradiance) depends mainly on latitude, season and time of day. The ratio of UVA to UVB also varies with the sun's height because of the differential effect of the ozone layer. Thus, terrestrial UVR typically contains ≤ 5% UVB (~295–315 nm) and ≥ 95% UVA. The minor UVB component is responsible for vitamin D synthesis" [4]

The steelman case for sunscreen is: you have a ~0.2% chance of dying a few years early from melanoma. Rigid sunscreen use will reduce some, not all, of that risk. We have not yet had the time to see exactly how much that risk is reduced (people only started using sunscreen en masse in the 90s) and sunscreen is usually not applied as directed [4.] Although existing studies are poor quality and do not take into account the many factors in vitamin D production and sun exposure (type of light, body surface area exposed, life of vitamin D in the body, etc) some of them - funded by industry - claim that you can still, somehow, produce sufficient vitamin D.

The anti case: the majority of sunscreen sold has been shown to be toxic; decades of sunscreen use has not had any appreciable impact on melanoma death rates; all improvements in mortality are associated with improved treatment, not sunscreen. The establishment says the reason mortality is not down is that everyone uses sunscreen incorrectly; imagine if condoms had no effect on birth rates, or airbags didn't decrease mortality because "you're using them wrong"... it is an outrageous defense. Sunscreen is designed to block the overwhelming majority of UVB, which is responsible for vitamin D synthesis; this would _trivially_ cause less vitamin D synthesis. The contra argument, that your body can still make sufficient vitamin D despite blocking the main pathway for its synthesis, is designed and funded nearly entirely by industry.

[0] NHANES 2009-2014, adults

[1] https://seer.cancer.gov/statfacts/html/melan.html

[2] https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6421a6.htm

[3] https://www.nejm.org/doi/full/10.1056/NEJMoa1809944

[4] https://pmc.ncbi.nlm.nih.gov/articles/PMC6899926/ (financed by L'Oréal and written by L'Oréal employees; the overwhelming majority of the research is industry funded)

[5] https://pmc.ncbi.nlm.nih.gov/articles/PMC6388383/

[6] https://pmc.ncbi.nlm.nih.gov/articles/PMC3154008/

[7] https://jamanetwork.com/journals/jamanetworkopen/fullarticle...