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academies
September 15-16, 2017 | Dallas, USA
International Conference on
VITAMINS, NUTRIGENOMICS & MALNUTRITION
Insights Nutr Metab 2017
Volume 1 Issue 1
Statement of the Problem:
Early humans, before migration out of East Africa
(~100,000 years ago), lived in surroundings abundant in solar radiation, and
to this day, traditionally living Hadza people in Tanzania have vitamin D
levels of ~115 nmol/L. Migration to other continents induced loss of skin
pigmentation to keep the same vitamin D
3
production as it was previously
in East Africa. Thus, the level of 115 nmol/L could serve as the measure
of optimal vitamin D status that was formed during millennia of human
evolution. It represents a target for contemporary humans usually having
a vitamin D deficit.
Methodology & Theoretical Orientation:
Krzyścin
et al.
(2016) modeled
vitamin D doses received by the Hadza adults during typical life activities
and found that the daily vitamin D
3
synthesis due to solar exposures
was equivalent to ~2000 IU of vitamin D
3
taken orally. To assess safety of
sunbathing to get such high doses by people with different skin phototypes,
we propose to calculate a health risk factor (HRF), i.e. a number of the
optimal vitamin D doses attained during maximal allowed duration of
sunbathing yielding exposure of 1 Minimal Erythemal Dose.
Findings:
It appears that HRF is independent on skin phototypes. The
optimal vitamin D dose is obtained safely, i.e. without erythema, for HRF>1.
Such conditions usually happen around sunny noon in spring/summer for
people exposing ~30% of the whole body.
Conclusion & Significance:
Analyses of HRF time series for several mid-
latitudinal sites show that young adults (~20 yr.) could obtain optimal
vitamin D
3
doses equivalent to 2000 IU vitamin D
3
taken orally for only 2-3
months per year. Such vitamin D
3
supplementation seems to be necessary
over the whole year for persons >59 yr. but it may be reduced to ~1000 IU in
spring/summer for outdoor active persons.
Speaker Biography
Janusz W Krzyścin has been involved in modelling surface UV radiation for almost 30
years. He has developed a model for serum 25(OH) vitamin D changes due to solar
exposure and elaborated theory for antipsoriatic heliotherapy to be carried out in any
country. He proposed a method of improving vitamin D
3
status by using UV transparent
garment made of fine linen that is especially important for persons exposing limited
skin area due to cultural/religious reasons. He is a leader of team producing free
smartphone apps for planning and monitoring healthy sunbathing.
e:
jkrzys@igf.edu.plOptimal cutaneous vitamin D synthesis: Balance between beneficial and harmful health effects of
solar UV-B
Janusz W Krzyscin
Institute of Geophysics, Poland