Optimal vitamin D3 daily intake of 2000 IU inferred from modeled solar exposure of ancestral humans in Northern Tanzania
Journal of Photochemistry and Photobiology B: Biology, Volume 159, June 2016, Pages 101–105, doi:10.1016/j.jphotobiol.2016.03.029
Janusz W. Krzyścin, , Jakub Guzikowski, Bonawentura Rajewska-Więch
• Duration of sunbathing for adequate vitamin D level is derived from the Hadza life style.
• A novel formula to calculate optimal solar exposure to get vitamin D is proposed.
• Daily oral supplementation of 2000 IU of vitamin D3 is recommended for in-door workers.
Recently, high serum 25-hydroxyvitamin D concentration (~ 110 nmol/L) was found in the Hadza tribe still keeping ancient hunter-gather life style. This level could serve as optimal vitamin D level that was built during millennia of human evolution. The personal vitamin D3 effective solar exposures of the Hadza adults are estimated using radiative model simulations with input from the satellite observations over lake Eyasi (3.7°S, 35.0°E). The calculations are carried out assuming the Hadza typical clothing habits and specific scenarios of the out-door activity comprising early morning and late afternoon working time in sun and prolonged midday siesta in the shade. The modeled doses received by the Hadza are converted to the vitamin D3 effective daily doses pertaining to the lighter skinned persons. We propose a novel formula to get adequate vitamin D level — exposure of 1/3 MED around local noon to 1/3 part of the whole body during warm sub-period of the year in the low- and mid-latitude regions. Such daily solar exposure is equivalent to ~ 2000 IU of vitamin D3 taken orally. For many contemporary humans with limited out-door activity habit achieving such daily norm requires vitamin D3 supplementation of 2000 IU throughout the whole year.
The hunter-gatherers nap in the shade for 6 hours in the middle of the day
The study noted that UVB in the shade varies by 10X - from 5% to 50% of direct sun
Not clear how much the study assumed: 5%. 10%.. . . 50%?
Seems that they might have found the 2000 IU recommendation then worked back.
Note: Even more Vitamin D needed if
- Obese (Hunter gatheres are rarely obese)
- Exposed to Roundup
- Exposed to smoke, DDT
- Have taken lots of antibiotics - especially when young
- Have low Magnesium in diet
- Have low Omega-3 in diet
- Elderly - gut (and skin ) less efficient in processing vitamin D
- Overview Dark Skin and Vitamin D
- 2000 IU of vitamin D- doctors trained that it was too much, but it is often too little
- Vitamin D needs in 2004:1000 IU, 10 years later same author says 3,500 IU
- Even taking as much as 4200 IU vitamin D 43 percent had less than 30 ng in blood – RCT Jan 2013
- Chart of Vitamin D levels vs race - April 2013 has the following chart