The flu and cold bugs are around us all year round, so why is it that people get these during the "Flu Season?"
There is no flu season because the flu doesn't go away and come back during these times.
It is the angle of the sun to our specific area.
Fill in the Form A Azimuth chart and Submit.
Check the middle column and see if any values are >49 during the flu season where u live.
Anything <50 will not provide UVB or vitamin D.
http://aa.usno.navy.mil/data/docs/AltAz.php
The amount of vitamin D that can be obtained by a fair skinned, red haired person in 15 minutes will take 8 hours for someone dark skinned living near the equator.
Most people end up working in doors, so their D levels go down.
Vitamin D is a hormone and needs to be converted by an enzyme in the body.
If there are any problems with the D receptors, liver, kidneys, enzymes, the D may not work.
"Vitamin D from the diet or dermal synthesis is biologically inactive and requires enzymatic conversion to active metabolites. Vitamin D is converted to 25-hydroxyvitamin D, the major circulating form of vitamin D, and then to 1,25-dihydroxyvitamin D, the active form of vitamin D, by enzymes in the liver and kidney. 1,25-dihydroxyvitamin D binds to the intracellular vitamin D receptor to activate vitamin D response elements within target genes. The half-life of 1,25-dihydroxyvitamin D is four to six hours, compared with two to three weeks for 25-hydroxyvitamin D and 24 hours for parent vitamin D."
http://www.uptodate.com/contents/metabolism-of-vitamin-d
No, they are not white, but dark skinned, so they have to be in the sun for 8 hours longer than whites to get the same vitamin D benefits.