Optimize vitamin D from the sun

This should be of special interest to people who:

Want vitamin D from the sun during shoulder seasons
- when there is not enough UV directly landing on the the skin
Are elderly - production of vitamin D in elderly skin is 1/3 to 1/4 that of in youthful skin
Have darker skin - production is as little as 1/4 that as light skin
Cannot get sun in the middle of the day - and must do it in the morning/late afternoon when there is far less UVB
Need a lot of vitamin D for health reasons but do not want to take supplements
Cannot afford the time or money for a winter sunny vacation or go to some high-altitude snow (altitude = 1.3X, snow = 1.8 X)

1 - Use Baby/Mineral Oil (SPF is effectvely less than zero)

Reduces the reflection/scattering of the sun rays and increasing depth of penetration - may increase the UV by about 80%
Appears that some oils are significantly better than others. for having negative SPF
Carrier oils have SPF of 2 to 80
thus should avoid such oils as Soybean, Jojoba, Sesame Seed, Shea Butter, Coconut, Olive, Avocado, Castor, Almond,
Baby oil/Mineral oil apparently have SPF = 0 1, 2, 3, 4, 5. 6
Amplifier Oil Amazon SPF =0
First ingredient is Mineral Oil. Some people indicate getting a tan (vitamin d?) faster with it than with no oil at all

2 - Use of concentrator/reflector to increase the UV intensity

Reflect additional sunlight onto the skin that would not get there otherwise
Suspect that a 50% increase should be possible

Have not yet seen such a reflector/concentrator, but here are some design considerations

Probably a different design lying down, sitting, and standing
Unlikely to need to adjust reflector position during the sunning - sun does not move much in < 1 hour
Probably need to adjust the reflector when it is to be used at a different time of the day
Low cost
Easily assembled and put into place/put away
Not blown away by the wind
Not harmed by rain
Reflect a minimal amount of IR (heat) - so that the person will not 'bake" - desirable, not required, and probably very expensive

Note: need a special coating to expect a front-coated mirror to reflect UV (thumbnail from Edmond Scientific)l

4 - Keep body perpendicular to the sun

Standing is worse, lying is better, a slant board is nice
- 45 degree slant board in shoulder seasons at latitude 45 (Ontario) or in summer at latitude 60 (Helsinki) would increase UV by 30%

5 - Hypothesis – you will get the most vitamin D from sun if you do not tan

By not spending so much time in the sun at a time you may not tan much, and thus will produce more vitamin D per minute

6 - Have enough cholesterol in your diet

Cholesterol is needed in the skin to produce vitamin D

7 - Get your sun in rural area - apparently 200% to 400% less UVB in urban areas

8 - Make sure you have adequate co-factors which increase bio-availability of vitamin D

Increased vitamin D from supplements: Magnesium 20%, Boron 25%, Vitamin K2 10%: perhaps also increase vitamin D from the sun.

9 - Perhaps have more monosaturated fats in your diet - such as almonds

This helps with vitamin D supplements, It might increase bio-availability of vitamin D from the sun

10 - Use one of the many sources of UV maps for all regions of the globe Available on the web

11 - Get vitamin D at a slower rate on cloudy days

scattered clouds = 10% longer time, broken clouds = 27% longer, overcast = 68% longer

12- Do not shower/wash soon after sunning

Vitamin D may be lost by showering after sunbathing – 2009
This might also due to another product of sun/UV, cis-urocanic acid being washed off from the skin with a shower

13 - Wear tan-thru shirt and/or shorts

Bought a tan-thru t-shirt and measured it: blocks only about 50% of the UVB
As of 2016 I own 3 shirts and 1 pair of shorts

14 - Reflect the hot sun away, while getting the VitaminD from UVB

Some places on Earth where the sun is very very hot some people avoid it totally.
Can make a special relector which only passes UVB - not UVA, nor visible, nor infra-red.
Would only want to get this intense UVB for a few minutes a day

Other suggestions for sunning

To minimize burning start the season with short sessions. As your vitamin D levels increases you can increase the amount of time in the sun
To minimize UV damage to your eyes wear glasses, sunglasses if you wish to also reduce the intensity of the light
To minimize wrinkles, cover your face - perhaps with a hat
To minimize possibility of sunning too long use a timer or locate yourself such that you will be in the shade when the time is up
To minimize burning rotate yourself - thus reducing amount of UV on a part of the skin
- Top, right side, bottom, left side
To minimize ants/insects crawling on you, use a lounge to keep your body off the ground
- make sure the lounge can be flat/slanted such that you can get sun on all sides of your body

Google Search (sunbathing OR sunbathing) (concentration OR concentrate OR reflect OR reflector OR solarium) generated some ideas

Put aluminum foil on the inside of an old refrigerator box, put the box on the ground, then lie in it
Put aluminum foil (or other very reflective material) on the south side of a building, and lie in front of the building

The more atmosphere the light has to go thru, the less UVB which gets to the ground

When your shadow is as long as you are, you get about 50% of UVB
The above methods would probably be of no use at all for those times that your shadow is say >3X as long as you are.
- That is, when the season is many months away from summer, or the time of day is many hours away from noon.