One size doesn't fit all: Why vitamin D treatment needs to be personalized

Don't count on summer to solve your vitamin D problem. While seasonal sun exposure can partially correct deficiencies built up over winter, many patients — including those with obesity, darker skin tones, advanced age, or heavy sunscreen use — remain deficient even in sunny climates. Modern indoor lifestyles and limited food fortification in Europe compound the issue, keeping deficiency rates stubbornly high.

The fix, according to endocrinologist José Esteban Jódar Gimeno, is individualized care — not blanket supplementation. For roughly half the population, a combination of sensible sun exposure (about 15 minutes of suberythemal exposure on arms, legs, or back outside peak hours), a balanced diet, and a healthy weight is sufficient. For the other half, targeted supplementation is warranted based on documented deficiency or elevated clinical risk.

Key Takeaways:

• Sufficiency threshold for the general population: ≥20 ng/mL; bone health target: ≥30 ng/mL
• High-risk groups needing supplementation include pregnant/lactating women, the elderly, and those with obesity, malabsorption, chronic kidney disease, or osteoporosis
• Correction regimens run 6–8 weeks, followed by individualized maintenance — similar to managing hypothyroidism
• Nonskeletal benefits of vitamin D are more evident in patients with true deficiency, not in those with already adequate levels

Why it matters: Over-supplementing patients with adequate vitamin D levels offers little benefit, while under-treating high-risk individuals can lead to bone loss, falls, and fractures. A risk-stratified, personalized approach is the most clinically sound strategy.