Vitamin D and Vacation
A February beach week in Mexico, the Caribbean, or Southern Europe delivers a genuine but temporary vitamin D boost. The magnitude often surprises people — a few days of tropical sun can raise 25(OH)D by 10–20 ng/mL — but so does how quickly the boost fades once you're back home. Vacation is not a year-round vitamin D strategy.
Typical numbers
- Fair-skinned adult starting at 20 ng/mL (winter deficient) — a week of beach sun in the tropics with realistic exposure (2–3 hours daily, some sunscreen) typically raises 25(OH)D to 35–45 ng/mL over the following 2–3 weeks.
- Darker-skinned adult starting at 15 ng/mL — smaller boost, maybe to 25–30 ng/mL.
- The boost peaks 2–3 weeks after vacation return (lag reflects 25(OH)D pharmacokinetics).
- Serum 25(OH)D then declines with normal winter kinetics — ~1–2 ng/mL per month back at high latitude without sun or supplement.
- By 3–4 months post-vacation, you're back to baseline.
The reserves angle
Some vitamin D from vacation exposure gets stored in adipose tissue and slowly released. See our reserves calculator for a pharmacokinetic model. Adipose stores buffer the decline somewhat but don't prevent it. A single summer holiday won't carry you through the following winter.
The sunburn / melanoma trade-off
Intermittent intense sun exposure — like a vacation from a temperate country to a tropical destination — is the single strongest recognised risk factor for melanoma, particularly if it produces sunburns. This is where the vitamin D trade-off becomes unfavourable: gaining 15 ng/mL of 25(OH)D on a vacation isn't worth a childhood sunburn or a serious melanoma risk factor. Sunscreen, hats, and gradual acclimation are essential.
Practical vacation vitamin D
- Enjoy the sunshine benefit — brief unprotected exposure (5–15 minutes, arms and legs) at the start of the day multiple times during the trip provides most of the vitamin D benefit with least burn risk.
- Then apply sunscreen for the rest of the day.
- Never seek sunburn to boost vitamin D — it doesn't work faster, and the cancer risk is real.
- Continue supplementation after the vacation — the boost fades within months.
- If you tend toward winter deficiency, one tropical vacation isn't the answer; year-round supplementation is.
The Northern European "sun holiday" pattern
Cross-sectional data from UK, Danish, and Swedish cohorts show adults who take annual Mediterranean holidays have modestly higher year-round 25(OH)D than non-travellers. The effect is measurable but modest — 3–5 ng/mL average annual difference. Individual variation is large.
Winter vacation strategy for high-latitude residents
A February beach week can meaningfully improve late-winter mood and 25(OH)D. But it doesn't replace supplementation. Northern European or Canadian adults who choose winter holidays for vitamin D benefit should still supplement year-round — treat the vacation as a bonus, not the strategy.