Sunlight and Vitamin D: A global perspective for health
Wacker M, Holick MF • Dermato-Endocrinology
Key Finding
Only ~1% of solar UVB reaches earth surface (ozone absorbs 99%); deficiency linked to autoimmune diseases, cancers, CVD, infections, and type 2 diabetes
Key Findings
- 1Only ~1% of solar UVB reaches earth; ozone absorbs ~99%
- 2Deficiency linked to autoimmune diseases, cancers, CVD, diabetes
- 3Synthesis affected by latitude, season, skin pigmentation, age
- 4Recommend combining food fortification, sun exposure, and supplementation
Original title: “Sunlight and Vitamin D: A Global Perspective for Health”
Plain English Summary
Comprehensive review of vitamin D synthesis from sunlight, factors affecting UV exposure, and global health implications of deficiency.
In-Depth Analysis
Study Details
Authors: Matthias Wacker, Michael F Holick
Institution: Boston University Medical Center
Journal: Dermatoendocrinology, 2013 Jan; 5(1):51-108
PMCID: PMC3897598
Key Points (from original paper)
Vitamin D Photobiology
"Vitamin D is the sunshine vitamin that has been produced on this earth" for over 500 million years.
- •7-dehydrocholesterol in skin absorbs UVB radiation
- •Converts to previtamin D3, then vitamin D3
UV Exposure Facts
- •Only ~1% of solar UVB radiation reaches earth surface
- •Ozone layer absorbs ~99% of UVB (wavelengths 291-320 nm)
Factors Affecting Synthesis
- •Season
- •Latitude
- •Altitude
- •Skin pigmentation
- •Sunscreen use
- •Age
Health Associations with Deficiency
Increased risk for:
- •Autoimmune diseases
- •Certain cancers
- •Cardiovascular disease
- •Infectious disease
- •Schizophrenia
- •Type 2 diabetes
Recommended Strategy
Combining:
- •Food fortification
- •Sensible sun exposure
- •Vitamin D supplementation
Source: PMC full text (PMC3897598)
Paradigm Relevance
How this study applies to different clinical perspectives:
Standard Medical
RelevantConventional clinical guidelines used by most doctors
Why it matters:
Supports recognition of vitamin D deficiency as common and consequential
Research Consensus
RelevantCurrent scientific understanding, often ahead of guidelines
Why it matters:
Establishes 32% deficiency rate in US population; supports higher targets than conventional 20 ng/mL cutoff
Metabolic Optimization
RelevantProactive targets for optimal health, not just disease absence
Why it matters:
Key reference for understanding optimal sun exposure, supplementation doses (2,000 IU shown safe in children), and population-specific factors affecting vitamin D status
Study Details
- Type
- Review Article
- Methodology
- Review article covering vitamin D photobiology, factors affecting synthesis (latitude, season, skin pigmentation, age), and health associations.
Evidence Quality
Review from PMC3897598. Authors Wacker and Holick from Boston University.
Related Biomarkers
Calculate & Evaluate on Metabolicum
Original Source
DOI (Digital Object Identifier) is a permanent link to this publication. Unlike website URLs that can change, a DOI always resolves to the correct source.
Related Studies
Health Effects of Vitamin D supplementation: Lessons Learned from Randomized Controlled Trials and Mendelian Randomization Studies
Bouillon R, et al • J Bone Miner Res • 2023
Cancer mortality: daily dosing RR 0.88 (95% CI 0.78-0.98, 10 trials); bolus RR 1.07 (ineffective); VITAL: normal BMI cancer OR 0.76; shift focus to deficient individuals
Vitamin D supplementation and total cancer incidence and mortality: a meta-analysis of randomized controlled trials
Keum N, et al • Annals of Oncology • 2019
Cancer mortality: 13% reduction (RR 0.87, 95% CI 0.79-0.96, p=0.005); Cancer incidence: no effect (RR 0.98, 95% CI 0.93-1.03, p=0.42)
International Vitamin D Supplementation Guidelines
Pludowski P, et al • Journal of Steroid Biochemistry and Molecular Biology • 2018
Target 25(OH)D levels of 30-50 ng/mL (75-125 nmol/L) recommended for general health; higher targets (40-60 ng/mL) for specific conditions.