Science Forums 2

[Michaelangelica]

Originally Posted by orbsycli

One dance a day
keeps the evils at
bay

Yes but not at night
All rave parties and wutch's coven meetings will now take place in day time

Title:
Vitamin D Synthesis by UV Radiation: the Importance of Ozone Monitoring
Authors:
Olds, W. J.; Moore, M. R.; Kimlin, M. G.
Affiliation:
AA(Australian Sun and Health Research Laboratory (ASHRL), Institute of Health and Biomedical Innovation (IHBI) Faculty of Health Queensland University of Technology, Kelvin Grove, Qld 4059 Australia ; w.olds@qut.edu.au), AB(National Research Centre for Environmental Toxicology (EnTox), University of Queensland 39 Kessels Road, Coopers Plains, Qld 4108 Australia ; m.moore@uq.edu.au), AC(Australian Sun and Health Research Laboratory (ASHRL), Institute of Health and Biomedical Innovation (IHBI) Faculty of Health Queensland University of Technology, Kelvin Grove, Qld 4059 Australia ; m.kimlin@qut.edu.au)
Publication:
American Geophysical Union, Fall Meeting 2006, abstract #A21F-0912
Publication Date:
12/2006
Origin:
AGU
AGU Keywords:
0422 Bio-optics, 0545 Modeling (4255), 2479 Solar radiation and cosmic ray effects, 7549 Ultraviolet emissions, 9330 Australia
Abstract Copyright:
(c) 2006: American Geophysical Union
Bibliographic Code:
2006AGUFM.A21F0912O
Abstract
The majority of humans rely on incidental sun exposure to maintain vitamin D sufficiency.
Depending on where thresholds of vitamin D "sufficiency" are defined, it was recently stated that up to one billion people worldwide have suboptimal vitamin D levels.
Even in sunny southeast Queensland, the world's skin cancer capital, a 2006 study uncovered deficiency rates of up to 78%
. Vitamin D regulates calcium absorption and inadequate levels are proven to result in osteomalacia, osteoporosis, rickets, bone pain and general skeletal weakness.

Recent evidence also suggests vitamin D plays a preventative role in autoimmune diseases including numerous cancers, diabetes, schizophrenia, coronary heart disease, depression and other disorders.

The most promising means of alleviating the worldwide burden of vitamin D deficiency seems to be by increased UV exposure.
However, a much more mature understanding of UV exposures encountered in everyday life is required.
This understanding is fundamentally founded in geophysics. UV exposures are strongly influenced by season/time of year, time of day, climate, location, pollution, aerosols and, importantly, ozone.

In this work, we use computer simulations to obtain daily totals of vitamin D producing UV at numerous latitudes during one year.
The ozone concentration is varied from 260 DU to 360 DU to determine the role of ozone variability on the ambient levels of vitamin D UV.
Vitamin D synthesis is highly dependent on UVB. In our results, we demonstrate that this has important implications.
Namely, vitamin D is strongly affected by ozone variability, since ozone filters UVB more strongly than UVA.

Moreover, since erythema (sunburn) can occur at UVA wavelengths, ozone variation will more strongly affect vitamin D synthesis than erythema.
Our results highlight that ozone monitoring is essential for understanding appropriate UV exposures for vitamin D health. . . .

Vitamin D deficiency in breastfed infants in Iowa
Journal title : Pediatrics. [ Pediatrics. ] , 2006 , vol. 118 , no 2 , pp. 603 - 610 [ 8 pages. ]
ZIEGLER Ekhard E. , HOLLIS Bruce W. , NELSON Steven E. , JETER Janice M.

Department of Pediatrics, University of Iowa
Iowa City, Iowa
Departments of Pediatrics, Biochemistry, and Molecular Biology, Medical University of South Carolina
Charleston, South Carolina

Language : Anglais
INIST shelf number : 6967
Publisher :
American Academy of Pediatrics
Elk Grove Village, IL
Etats-Unis
Abstract : OBJECTIVE. The purpose of this work was to assess the vitamin D status of breastfed infants living in Iowa (latitude: 41�N).

METHODS. Blood samples and dietary records from 84 breastfed infants participating in another study were used for a survey of vitamin D status at 280 days of age.
The vitamin D status of those (35 infants) who did not receive preformed vitamin D at 280 days of age (unsupplemented infants) was assessed longitudinally between 112 days and 15 months of age. Plasma 25-hydroxyvitamin D and, in most cases, parathyroid hormone and alkaline phosphatase were determined.

RESULTS. At 280 days of age, 10% of breastfed infants were vitamin D deficient (25-hydroxyvitamin D <11 ng/mL).
Deficiency was significantly more prevalent among dark-skinned infants and during winter and occurred exclusively in unsupplemented infants.

During winter, 78% of unsupplemented infants were vitamin D deficient. During summer, only 1 infant who had dark skin pigmentation was vitamin D deficient.
Longitudinal assessment of unsupplemented infants similarly showed that the majority of breastfed infants were vitamin D deficient during winter. Severe deficiency (25-hydroxyvitamin D <5 ng/mL) was common and was accompanied by elevation of parathyroid hormone and alkaline phosphatase.
The prevalence of vitamin D deficiency decreased with age but was still 12% at 15 months of age if no preformed vitamin D was received.

CONCLUSIONS. Vitamin D deficiency, including severe deficiency, was common among breastfed infants in Iowa who did not receive preformed vitamin D.
Deficiency occurred mostly during winter but was not completely absent during summer.
It affected infants with light as well as dark skin pigmentation. Consumption of preformed vitamin D from vitamin supplements or formula is effective in preventing vitamin D deficiency.
Vitamin D supplementation should be provided to all breastfed infants.

Article@INIST

I wonder what the implications of early childhood D deficiency are?
Should ALL infants have D supliments as the authors suggest?
Or
Only those in Iowa?
Again a small study -35 & A bit hard to work out how big the "control" (Vit D suplimented) group was from the abstract (49?)