Despite abundant sunshine in many regions, vitamin D deficiency continues to be widely reported particularly in urban populations. The paradox lies in modern lifestyle patterns: prolonged indoor work hours, sunscreen use, air pollution, limited skin exposure, and cultural clothing practices significantly reduce effective ultraviolet B (UVB) synthesis. As a result, clinicians increasingly encounter low 25(OH)D levels even in sun-rich countries—prompting a surge in testing and empirical supplementation.
But what constitutes realistic sunlight exposure? For most individuals with light-to-medium skin tones, approximately 15–30 minutes of midday sun exposure (10 am–3 pm), 2–3 times per week , with face, arms, and legs exposed, may be sufficient for cutaneous vitamin D synthesis though this varies by latitude, skin pigmentation, season, and pollution levels. Darker skin requires longer…
