Comparison of people over 50 who holiday outside the UK at least once a year (n = 281) and people over 50 who holiday outside the UK less than once a year or never (n = 851).

<p>Unpaired t-tests applied to continuous data; chi-square tests applied to categorical data.</p

Distribution of age and crude vitamin D in age-matched Orkney and mainland Scotland datasets.

<p>The mainland dataset excludes people from above the 57^th degree of latitude.</p

Characteristics of ORCADES Study participants (n = 1972).

<p>Characteristics of ORCADES Study participants (n = 1972).</p

Characteristics of the Rotterdam Study (RS).

<p>Characteristics of the Rotterdam Study (RS).</p

Percentage of people per age group in ORCADES who holiday outside the UK at least once a year.

<p>People over 50 take significantly more holidays than those under 50.</p

Mean May-adjusted vitamin D (nmol/L) according to season of venepuncture (high season (April-September, n = 96) vs low season (October-March, n = 185)) in people over 50 who take a holiday outside the UK at least once a year.

<p>Linear regression with May-adjusted vitamin D as the outcome.</p

Map of Orkney in relation to the Scottish mainland and north-west periphery of Europe, with 57^th and 59^th degrees of latitude.

<p>Map of Orkney in relation to the Scottish mainland and north-west periphery of Europe, with 57^th and 59^th degrees of latitude.</p

Mean crude vitamin D concentration (nmol/L) per month by location, using age-matched data.

<p>Orkney’s mean vitamin D is higher than the mainland for every month except August and November. Each study ran over consecutive years and measurements taken in the same month each year were pooled.</p