Hi Andrew;

From reading a couple of abstracts it seems that adequate Vitamin D levels
can be obtained by sunshine exposure times of around a half an hour a day
and I'll assume somewhat longer in more Northern climates than Florida or
Saudi Arabia. This is significantly longer than I had previously thought
(10-15 minutes a day).

Still, one does not need to live around the equator, as you seem to say, in
order to generate adequate levels of Vitamin D from sunshine.

Marilyn

. . .

Vitamin D deficiency in Florida, the Sunshine State.

Woods DR, Hoffman NB, Thomas WC Jr.

Several years may be required for development of clinically evident
osteomalacia in previously healthy subjects deprived of exposure to sunlight
or enriched dietary sources of vitamin D. In a survey of residents of a 120
bed VA nursing home who had been patients there for two to six years, 17
were found to have x-ray or laboratory findings suggestive of the presence
of vitamin D deficiency. Bone biopsy in eight of these 17 patients revealed
definite osteomalacia in three patients. Thus, vitamin D deficiency may
develop in confined, nonvitamin D fortified patients in Florida just as in
more northern climes. Daily exposure for 30 minutes to sunshine or oral
administration of 2.5 mg of vitamin D2 or D3 twice yearly has been
recommended to prevent deficiency of this vitamin.

PMID: 2600569 [PubMed - indexed for MEDLINE]

. . .

Exposure to sunlight and vitamin D deficiency in Saudi Arabian women.

Fonseca V, Tongia R, el-Hazmi M, Abu-Aisha H.

Plasma 25-hydroxy cholecalciferol (25-OH vitamin D) concentrations were
measured in 31 adult Saudi Arabian women who presented with acute minor
illness. Patients with chronic diseases, malignancy and overt metabolic bone
disease were excluded from this study. The median plasma 25-OH vitamin D
concentration was 6 ng/ml (range: 2-18 ng/ml). Only three subjects had a
concentration within the normal range (10-55 ng/ml). Plasma 25-OH vitamin D
concentrations were significantly lower in subjects living in apartments
than in those living in villas or rural areas (P less than 0.02). When
direct questioning was used to assess exposure to sunlight, plasma 25-OH
vitamin D concentrations were significantly lower in those subjects whose
average exposure was less than 30 min daily than those whose exposure was
more than 30 min daily (P = 0.002). Our findings confirm the importance of
inadequate exposure to sunlight in the aetiology of vitamin D deficiency.
Social customs may contribute to this deficiency in spite of abundant
sunshine. Direct questioning to assess the adequacy of sunlight exposure is
an essential part of history taking in cases of suspected vitamin D deficiency.

PMID: 6483701 [PubMed - indexed for MEDLINE]