Evidence-based articles about vitamin D, sun exposure, and health optimization.
41 articles
A UV index vitamin D calculator needs more than a single number — your location, season, and skin type all change how much sun you actually need. Here's the science.
Low vitamin D levels appear consistently in people with depression, but correlation isn't causation. Here's what randomized controlled trials reveal about supplementation and mood.
Skin synthesis of vitamin D drops by up to 75% with age. Here's what the evidence shows about why older adults are at high risk and what to do about it.
Low vitamin D has long been linked to heart disease risk in observational data. Here's what large randomized trials like VITAL now say about cause and effect.
Low vitamin D levels consistently appear in people with poor sleep quality and short sleep duration. Here's what the clinical data actually shows.
Pregnancy raises vitamin D demand for both mother and baby. Here's what clinical trials and large cohort studies show about targets, risks, and how to meet your needs safely.
Low vitamin D levels appear repeatedly in autoimmune conditions from MS to rheumatoid arthritis. Here's what trials and large cohort studies actually show — and what remains unresolved.
Sun and supplements both raise 25(OH)D, but the speed and ceiling differ. Here's what the evidence says about which works faster and when each has the edge.
UV index alone won't tell you how long to stay outside for vitamin D. Your skin's melanin content can shift the required exposure time by 300–500%. Here's the science.
UV index tells you whether your body can make vitamin D right now — but location and season determine whether that window even opens. Here's the science.