Girija,
Vit D deficiency is not uncommon in people of south asian origin, as they have higher pigment in the skin - and especially if affluent, as they do not go in the sun as often as their poorer counterparts! at least half an hour, sleeveless, 2-3 days a week in the sun advised. Very common in the uk for this group, but in San Diego you should not be so prone. Another factor is aging as the skin gets thinner, this should not affect you, on the other hand PD is more often found in older people, so is this a factor. Perhaps. PD can affect the skin, make is either drier or very damp. Dry skin can often be much thinner and fragile, and have read that thin skin does not absorb Vit D so well. And perhaps the disease itself leaves us with something that you would call 'going on'.

Another factor could be that vegetarians & vegans also get Vit D deficiency due to less cholesterol, which is a factor in absorbtion of Vit D through the skin...........

I get mine tested next week. Will post here if it is also v low.