28 2019 Skin Cancer Prevention Progress Report Vitamin D Vitamin D is needed for health and to maintain strong bones.24,25 The body makes vitamin D when skin is directly exposed to the sun.24,25 Vitamin D is also found in some foods.24,25 Recommended dietary intakes of vitamin D are set on the assumption of little sun exposure because of public health concerns about skin cancer.25 However, improving sun protection across the population could potentially lead to reduced vitamin D concentrations for some people if they do not increase their vitamin D intake from diet or supplements. The National Health and Nutrition Examination Survey regularly collects data on serum vitamin D concentrations in the U.S. population.24 These data can be used to monitor vitamin D levels and document potential unintended consequences of skin cancer prevention interventions, such as increases in vitamin D deficiency.26 According to the National Academy of Medicine (formerly the Institute of Medicine), people with serum vitamin D levels less than 40 nmol/L are at increased risk for adverse health outcomes, and levels greater than 125 nmol/L may also be reason for concern.25 Analyses of the prevalence of low serum vitamin D concentrations among the U.S. population aged 12 years or older from 1988 to 2010, the most recent years for which data are available, indicated that the prevalence of low serum vitamin D concentrations has not changed significantly in recent decades.26 During 1988–1994, 16% of the U.S. population had serum vitamin D concentrations below 40 nmol/L; during 2009–2010, the prevalence was 15%.26
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