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to optimize D production:
midday summer sun
full body (as little clothing as is possible)
unprotected (ie no sunscreen, no shade)
to the point just before a burn occurs - then cover up, seek shade, apply s/s or head inside
on days you can't do the above, supplement D. how much is highly variable. the further north one goes, the less 'summer' sun is available. in atlanta (33º), in terms of D exposure, summer is about 16 weeks from midmay till midsept. Before and after that, D production drops off dramatically to the point that it's not really worth it. At 55ºN, one needs D supplements year round regardless of skintone and length of time outside.
ETA: be careful about supplementing D while getting lots of D from sun.
assume that if you wear clothes that cover most of your skin, work indoors, avoid midday sun for whatever reason or lifestyle choice, that you'll likely
need amounts right around that 1000 IU per 25 lbs body weight. I've been testing and 'treating' my D levels for about six years (and follow D levels for nearly 100 people), no longer get any 'incidental' d from sun - so on days I don't get purposeful exposure, I take 1,000 IU per 25 lbs body weight - so do my kids. I also follow D levels for nearly 100 people - family members and friends - and most are needing right at 1000 IU per 25 lbs body weight per day as they tend to be fairly sun avoidant or protective (s/s and/or sun protective clothing) when they are getting exposure. A couple are getting sufficient levels with less than that even though they are VERY sun avoidant and about 10% are needing significantly more than that amount.
Other things to keep in mind: a tan doesn't indicate good 25(OH)D levels. We can get great tans in high pressure UVA beds and still have low D. We can get tan from 'incidental' exposure, early day exposure, later day exposure, and even through windows if sitting close enough - but in none of those produce D. We can even obtain a burn from excessive UVA exposure and not produce enough D.
Topical C preparations offer some protection against oxidative damage from UV. High fruit/veg intake supports high antioxdiant levels which offers additional protection against oxidative damage.
Very dark skintones (think west africa) will need 6 hours per day of outdoor tropical sun year round to maintain excellent 25(OH)D levels. Distance from the equator and skintone are HUGE factors that affect sun and vitamin D production - altitude is very significant as well.
At 55ºN, one needs D supplements year round regardless of skintone and length of time outside.
Yiekes - I am at 59 degrees north, and grew up at 69 degrees north! I have just recently begun to take supplements (1000 - 1500 mg krill oil, the box recommends 500 - 1000 mg a day), but as a kid I ate a lot of fish, cod, coalfish etc. I also loved liver paste. I've set up an appointment for a health check and getting my blood draw on june 7th, maybe I should check my 25(OH)D levels as well.
Sometimes you need to be told the truth in order to be able to see it.
Maybe the next Atlanta event should be running around in swimsuits gettin' toasted by Old Man Helios?
"To shed all the illusory rights & hesitations of history demands the economy of some legendary Stone Age--shamans not priests, bards not lords, hunters not police, gatherers of paleolithic laziness, gentle as blood, going naked for a sign or painted as birds, poised on the wave of explicit presence, the clockless nowever." --Hakim Bey, TAZ
I haven't used sunscreen, OR gotten a sunburn, since I started using CO as a moisturizer, and I'm out a LOT. I can't remember who told me this, but it was somebody here...that CO has about an SPF of 4 when applied to the skin. I also cook with it a lot, so skin gets it from both the inside AND the outside