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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.pl

Optimal cutaneous vitamin D synthesis: Balance between beneficial and harmful health effects of

solar UV-B

Janusz W Krzyscin

Institute of Geophysics, Poland