Production Of Vitamin D3 Research Articles

Evidence That Loss-of-Function Filaggrin Gene Mutations Evolved in Northern Europeans to Favor Intracutaneous Vitamin D3 Production.

Skin pigmentation lightened progressively to a variable extent, as modern humans emigrated out of Africa, but extreme lightening occurred only in northern Europeans. Yet, loss of pigmentation alone cannot suffice to sustain cutaneous vitamin D3 (VD3) formation at the high latitudes of northern Europe. We hypothesized that loss-of-function mutations in the epidermal structural protein, filaggrin (FLG), could have evolved to sustain adequate VD3 status. Loss of FLG results in reduced generation of trans-urocanic acid, the principal endogenous ultraviolet-B (UV-B) filter in lightly-pigmented individuals. Accordingly, we identified a higher prevalence of FLG mutations in northern European populations when compared to more southern European, Asian and African populations that correlates significantly with differences in circulating 25-OH-VD3 levels in these same populations. By allowing additional UV-B penetration and intracutaneous VD3 formation, the latitude-dependent gradient in FLG mutations, likely together with other concurrent mutations in VD3 metabolic pathways, provide a non-pigment-based mechanism that sustains higher levels of circulating VD3 in northern Europeans. At the time that FLG mutations evolved, xerosis due to FLG deficiency was a lesser price to pay for enhanced VD3 production. Yet, the increase in FLG mutations has inadvertently contributed to an epidemic of atopic diseases that has emerged in recent decades.

Diet, sun, and lifestyle as determinants of vitamin D status.

Vitamin D status can be assessed by measuring concentrations of 25-hydroxyvitamin D (25(OH)D). Sunlight is the most important source of vitamin D and stimulates the production of vitamin D3 in the skin during the summer, depending on age, skin pigmentation, clothing style, and sunscreen use. Seasonal variation in serum 25(OH)D is between 10 and 20nmol/L in adults and almost absent in nursing home residents. Sunscreen use decreases, but does not abolish, vitamin D production in the skin. Clothing style has a large influence on vitamin D production. Furthermore, vitamin D status can be improved by ingestion of fatty fish and the fortification of milk or orange juice. A high dietary calcium intake has a vitamin D-sparing effect, because it increases the half-life of 25(OH)D. A combination of sunlight exposure, nutrition, food fortification, and supplements is desirable to obtain sufficient vitamin D status in the population of most countries throughout the year.

Prevalence of vitamin D deficiency in high Andean Ecuadorian children (804.13)

Background: Vitamin D deficiency is a global public health problem. Vitamin D levels in Andean Ecuador have been assumed to be sufficient given its equatorial high altitude, which is conducive to cutaneous production of vitamin D3. However, there is a dearth of data on 25(OH)D status in children in Andean Latin America.Objective: To determine the vitamin D status of children ages 6‐36 months residing in Quito, Ecuador who were categorized into normal, mildly, or clearly underweight, based on weight‐for‐age z‐scores (WAZ).Design: This study was conducted among a sub‐sample of subjects participating in a 2x2 factorial randomized controlled trial of Vitamin A and Zinc Prevention of Pneumonia (VAZPOP); 2400 children residing in 5 neighborhoods of northwestern Quito, received 48 weeks of supplementation with vitamin A, zinc, or both. Vitamin D insufficiency was defined as a serum 25(OH)D concentration of 20‐29 ng/mL and deficiency as < 20 ng/mL. Serum 25(OH)D levels were assayed using an automated immunoassay system (Immunodiagnostics Systems).Results: Of the 526 children studied, 183 (35%) were vitamin D deficient and 235 (45%) were insufficient, while only 108 (20%) had adequate serum levels (>29 ng/mL). Older children (蠅12 months) were less likely to be vitamin D sufficient than infants (<12 months) (OR=0.58, 95% CI:0.33 ‐0.89). Mildly and clearly underweight children were less likely to have sufficient 25(OH)D levels compared with normal weight children (OR=0.50, 95% CI:0.31 ‐0.89) and (OR=0.51, 95% CI:0.33 ‐0.80), respectively. Socio‐economic status indicators were not significant determinants of 25(OH)D status.Conclusions: Vitamin D insufficiency and deficiency were common (80%) in Ecuadorian children despite residence at equatorial high altitude. Pediatric supplementation with vitamin D and/or food fortification is warranted. Further studies are needed to ascertain other determinants of vitamin D deficiency in this region.Grant Funding Source: Supported by Sight and Life

Ultraviolet Light Exposure and Response to Dietary Vitamin D3in Two Jamaican Anoles

Abstract In Jamaica, free-living male and female-sized Anolis sagrei are exposed to more natural ultraviolet-B (UVB) from sunlight than male and female-sized Anolis lineatopus. In the laboratory, we tested predictions derived from the hypothesis that Anolis possess a mechanism for behaviorally photo-regulating their exposure to UVB depending on their dietary intake of vitamin D3. Anolis sagrei voluntarily exposed themselves more frequently to visible and UVB light and received higher doses of UVB in an artificial light gradient when fed a low vitamin D3 diet for 6 weeks than when subsequently fed a high dietary vitamin D3 diet for 6 weeks. When we returned the anole's diet to the low vitamin D3 regimen for a third 6-week period, UVB exposure remained lower than in the first 6-week period. This suggests an initial UV photo-regulatory adjustment to high dietary vitamin-D3 but a slow return to greater reliance on UVB-induced endogenous vitamin D3 production. Conversely, while exposing themselves to UVB with ...

Differences in colon cancer incidence rates by latitude.

e14627 Background: There is significant decrease in the ultraviolet B photons reaching the earth’s surface during November to February (Holick MF Am J Clin Nutr. 2004 Dec; 80(6 Suppl):1678S-88S). This results in little if any vitamin D3 production in the skin during this period. This study was conducted to evaluate difference in colon cancer age adjusted incidence rates in the northern (latitude ≥37o N) and the southern (latitude < 37oN) regions in the contiguous United States during 1973-2008. Methods: Patients, aged 20 years and older, who had been diagnosed with colong cancer during January 1973 and December 2008, were selected from the Surveillance, Epidemiology, and End Results (SEER) 13 database. Based on the counties’ centroid, northern (latitude ≥37o N) and southern (latitude < 37oN) regions were determined. We compared age adjusted incidence rates (AAIR) of colon cancer in the southern and northern regions among cohorts of patients categorized by age (≥20, 20-64, ≥65 years), gender (Men, Women) and Race (Caucasians, Blacks, Others). The AAIR was calculated per 100,000 population. We used SEER*Stat software to calculate age adjusted incidence rate, incidence ratio, confidence interval (CI, 95%) and P value. Results: There were 314,975 cases of colon cancer diagnosed among 608,245,557 US population during 1973-2008. The overall colon cancer AAIR was 57.1 per 100,000 population studied. The incidence rates were 49.1 in the south and 58.7 in the north of 37oN latitude, (95% CI 1.18-1.20, p<0.05). The AAIRs for patients in the age group 20-64 years were 17.9 and 18.8 in the southern and northern regions, (CI 95%, 1.0346-1.0697), p<0.0005 respectively. The incidence rates for patients aged ≥65 years were 194.3 and 243.9 in the southern and northern regions, (CI 95%, 1.0346-1.0697) p<0.0005. Similarly, the AAIRs were significantly higher in the northern region compared to southern region for both sexes and all ethnic groups. Conclusions: Colon cancer age-adjusted incidence rate is significantly higher in the Northern compared to the Southern region of the US. The higher incidence of colon cancer in the North may be related to lack of sunlight exposure and relative vitamin D deficiency.

Vitamin D: light side and best time of sunshine in Riyadh, Saudi Arabia

Low levels of 25-hydroxyvitamin D have been documented among inhabitants of the wider Middle East and North African countries. Sunlight has long been recognized as a major provider of vitamin D. In this study we aimed to determine the optimum time for sun exposure in the Central region of Riyadh, Saudi Arabia. Ampoules containing 7-dehydrocholesterol in ethanol were exposed to sunlight every hour starting from sunrise until sunset in July and December. Our results demonstrated that the time of the day has a major influence in vitamin D production. In this study, summer production of previtamin D3 was observed to occur between 8:00 PM to 4:00 PM with peak hours between 10:00 AM to 12:00 PM. During wintertime however, the conversion began later at around 9:30 AM and ended sooner at 2:00 PM, with peak hours at 10:00 AM to 12 noon. In conclusion, the optimum time to get sun exposure for vitamin D3 production in Riyadh, during summer is from 9:00 AM and before 10:30 AM, as well as after 2:00 PM until 3:00 PM, while during winter it's from 10:00 AM until 2:00 PM. These times are important on a public health perspective, as it's free, relatively safe and the most enjoyable. This strategy is a highly efficacious way for improving the vitamin D status for children and adults and preventing vitamin D deficiency.

Abstract 3707: Early stage inhibition of murine mammary carcinogenesis by ultraviolet radiation.

Abstract Epidemiological studies of geographical variations in breast cancer mortality rates have found increased death rates at higher latitudes in USA and other countries 1. This breast cancer latitudinal gradient is hypothesized to be mediated by ultraviolet radiation (UVR) - produced vitamin D3. We first have tested this latitudinal hypotheses using the well-described C3(1)/Tag transgenic murine mammary carcinogenesis model2. We have found that UVR significantly prolongs palpable tumor - free survival (135±23 vs.118±18 days) and reduces the tumor burden and multiplicity (2.9±1.6 vs. 7.2±2.3 tumors), but does not alter the time between the appearance of the first palpable tumor and death in Tag female mice. Therefore we have focused on the effects of UVR on earlier stage carcinogenesis. Tag transgenic female mice have a time-dependent increase in the incidence of ductal carcinoma in situ (DCIS) - like incidence. Thus, Tag mice develop ductal epithelial atypia in 50% of mice at age 8 wks, with progression to intraepithelial neoplasia (resembling human DCIS) in 70-90% of mice (in at least one gland) at 10-13 wks, and DCIS-like changes and early invasion in 100% of mice at age 14-15 wks. We compared weekly the similarity of histological changes between the pairs of mammary glands and found no significant gland site-to-gland site variations. UVR treatment, 350mJ/cm2 thrice weekly from age 6 wks to 15 wks, reduced both the percentage of DCIS-bearing mice (65, 60, 51, 32 and 20% reduction at week 8, 9, 11, 13 and 14) and the percentage of DCIS-bearing glands in each animal (82, 55, 66, 20 and 19% reduction at week 9, 11, 13, 14 and 15). The mechanism of the UVR-mediated prevention of the murine mammary carcinogenesis is unclear but there is evidence favoring a Hedgehog (HH) signaling-dependent mechanism, since D3 is a potent inhibitor of the HH signaling pathway, which is upregulated in many cancers including breast cancer3-5. Consistent with this idea we found that UVR reduces DCIS-like changes in Ptch+/- mice. Taken together our results support our hypothesis that inhibition of early stage mammary carcinogenesis by UVR-produced vitamin D3 underlies the latitudinal gradient. 1. Garland, F. C. et all. Prev Med 1990, 19, 614-22. 2. Green, J. E. et all. Oncogene 2000, 19, 1020-7. 3. Bijlsma, M. F. et all. PLoS Biol 2006, 4, e232. 4. Moraes, R. C. et all. Development 2009, 136, 1423-32. 5. Lewis, M. T. et all. Development 1999, 126, 5181-93. Citation Format: Anastasia M. Makarova, Grace Wang, Lynn Wang, Joy Wang, Yefim Khaimskiy, Ervin H. Epstein. Early stage inhibition of murine mammary carcinogenesis by ultraviolet radiation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3707. doi:10.1158/1538-7445.AM2013-3707

Letter to the Editors: Lighting for Different Healthcare Settings

According to Michael White, Light should be interpreted as an architectural material. Mr. White made his pronouncement at the Annual Conference of the Academy of Neurosci- ence for Architecture in September 2012, and went on to say that in addition to being economically sound and aesthetically pleasing, the specification of light should address the biology of human health and well being.Mr. White, an EDAC-certified senior lighting design consultant for the firm Shuler Shook in Minneapolis, Minnesota, was a guest speaker in a panel session titled That Informs Light- ing Design in Healthcare Settings. The other pan- elists were Sanchin Panda, PhD, a neuroscientist at the Salk Institute for Biological Studies in La Jolla, California, where the conference was being held; Eve Edelstein, PhD, a neuroscientist and associate professor at the University of Arizona College of Architecture, Planning, and Landscape Architec- ture; and Mark Rea, PhD, a biophysicist and direc- tor of the Lighting Research Center at Rensselaer Polytechnic Institute. Like his colleagues, White was concerned with the use of indoor electrical lighting.People living and working today in the most advanced industrial countries spend the majority of their daylight hours and an average of six hours after nightfall under artificial light. Research has shown that in the absence of full-spectrum sun- light, individuals are susceptible to detrimental effects (Veitch et al., 2008). Conventional candes- cent and/or fluorescent lamps have been implicated in aggravating fatigue, depression, aggression, eye strain, dyslexia, tooth decay, reduced muscle strength, obesity, and diabetes. The lack of exposure to ultraviolet radiation impairs the body's ability to absorb calcium, produce vitamin D3, and stimulate the neuroendocrine system to destroy a wide range of microorganisms that might otherwise lead to hospital-acquired infections (Braun, 2008). In the 1960s, fluorescent lamps were engineered to simulate the natural outdoor environment in both the visible and non-visible UV wavelengths. How- ever, because of legal concerns and the cost of pro- duction, this type of fixture never became widely available in the United States.Sunlight deficiency and the typical measures taken to compensate this deficiency may negatively affect one's sleep/wake cycles, which in turn may cause cardiovascular disorders (Edelstein et al., 2007) and cancer (Stevens et al., 2001). Electrical light- ing codes and standards with an emphasis on ener- gy efficiency often require insufficient footcandles during the day and too much light intensity at night for normal circadian function. Nurses and doctors assigned to shift work and patients who are continually exposed to illumination are unable to entrain (or align) with their 24-hour natural rhythms (Schernhammer et al., 2001). Our under- standing of sleep disorders was greatly enhanced by the 1998 discovery of melanopsin retinal ganglion cells, a type of photoreceptor in front of the eye's retina that provide signals to the suprachiasmatic nucleus (SCN), the brain's master clock (Hatori et al., 2010). These newfound cells project to many other brain regions as well, influencing countless aspects of human physiology.There is currently enough evidence to assist design- ers, architects, and engineers in selecting the prop- er type and sufficient quantity of light for different healthcare settings. It is critical in preventing errors such as misreading charts and medication labels, or a patient's vital signs. Knowing that a cool color temperature as in blueish white suppresses mel- atonin in humans and activates the brain means that this type of lighting should not be specified above a hospital patient's bed at night, but that it may benefit those with dementia in long-term care facilities by boosting their activity levels during daytime hours (Holtzman, 2010). …

Mushrooms not only Produce Vitamin D2 but can also Produce Vitamin D3 and Vitamin D4

It has been previously reported that mushrooms have the ability to produce both vitamin D2 and vitamin D4. Using high performance liquid chromatography with a photodiode ultraviolet (UV) absorbance detector we detected several vitamin Ds and provitamin Ds in mushroom samples. UV irradiated mushroom powder (Monterey Mushroom) extracted with methanol was run on a Zorbax C18 column along with standards for vitamin D2 (D2)and vitamin D3 (D3). The resulting chromatograms revealed 3 separate peaks with retention times of 11.2, 12.9 and 13.9 minutes that were similar to retention times for standards of D2, D3 and vitamin D4 (D4), respectively. Additionally, isolated pro‐vitamin D from a shitake mushroom sample was run on a Zorbax ODS column along with standards for pro‐vitamin D2 (pro‐D2; ergosterol) and provitamin D3 (pro‐D3; 7‐dehydrocholesterol). The resulting chromotograms revealed three separate peaks with retention times of 7.4, 8.2 and 8.8 minutes which were consistent with retention times for standards of pro‐D2, pro‐D3 and pro‐D4, respectively. The UV absorption spectra for D2, D3, D4, pro‐D2, pro‐D3 and pro‐D4 in the mushroom samples matched the UV absorption spectra of a 5,6‐cis triene of vitamin D and a 5,7‐diene of pro‐vitamin D standards. These results demonstrate that in addition to vitamin D2, mushrooms can also produce vitamin D3 and vitamin D4.

Photobiology of vitamin D in mushrooms and its bioavailability in humans

Mushrooms exposed to sunlight or UV radiation are an excellent source of dietary vitamin D2 because they contain high concentrations of the vitamin D precursor, provitamin D2. When mushrooms are exposed to UV radiation, provitamin D2 is converted to previtamin D2. Once formed, previtamin D2 rapidly isomerizes to vitamin D2 in a similar manner that previtamin D3 isomerizes to vitamin D3 in human skin. Continued exposure of mushrooms to UV radiation results in the production of lumisterol2 and tachysterol2. It was observed that the concentration of lumisterol2 remained constant in white button mushrooms for up to 24 h after being produced. However, in the same mushroom tachysterol2 concentrations rapidly declined and were undetectable after 24 h. Shiitake mushrooms not only produce vitamin D2 but also produce vitamin D3 and vitamin D4. A study of the bioavailability of vitamin D2 in mushrooms compared with the bioavailability of vitamin D2 or vitamin D3 in a supplement revealed that ingestion of 2000 IUs of vitamin D2 in mushrooms is as effective as ingesting 2000 IUs of vitamin D2 or vitamin D3 in a supplement in raising and maintaining blood levels of 25-hydroxyvitamin D which is a marker for a person's vitamin D status. Therefore, mushrooms are a rich source of vitamin D2 that when consumed can increase and maintain blood levels of 25-hydroxyvitamin D in a healthy range. Ingestion of mushrooms may also provide the consumer with a source of vitamin D3 and vitamin D4.

Vitamin D status and sun exposure in India

Background: Little if any cutaneous production of vitamin D3 occurs at latitudes above and below 35° N and 35° S during the winter months. It was postulated that those residing in tropics synthesize enough vitamin D3 year round. Several studies have documented the effect of latitude, season and time of the day on the cutaneous production of vitamin D3 in an ampoule model. Studies from India have shown high prevalence of vitamin D deficiency despite abundant sunshine. Methods: We studied the influence of season and time of the day on synthesis of previtamin D3 in an ampoule model in Tirupati, (latitude 13.40° N and longitude 77.2° E) south India, between May 2007 to August 2008. Sealed borosilicate glass ampoules containing 50 μg of 7-DHC in 1 ml of methanol were exposed to sunlight hourly from 8 a.m. until 4 p.m. The percent conversion of 7-DHC to previtamin D3 and its photoproducts and the percent of previtamin D3 and vitamin D3 formed was estimated and related to solar zenith angle. Results: The percent conversion of 7-DHC to previtamin D3 and its photoproducts and formation of previtamin D3 and vitamin D3 was maximal between 11 a.m. to 2 p.m. of the day during the entire year (median 11.5% and 10.2% respectively at 12.30 p.m.). Conclusions: Therefore at this latitude exposure to sunlight between the hours of 11 a.m. and 2 p.m. will promote vitamin D production in the skin year round.

Selective Vitamin D Receptor Modulators (SVIMS) as Potential Adjuvant Therapeutic Agents

Copyright: © 2013 Li W. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Vitamin D3 (cholecalciferol, D3) is one of the most important forms of vitamin D in human health [1-4]. There are two sources for human beings to obtain vitamin D3. The first source is the conversion of 7-dehydrocholesterol (7-DHC) in the skin to pre-vitamin D3 by UVB irradiation from the sunlight, followed by thermal isomerization to produce vitamin D3 (Figure 1) [5]. This is a tightly regulated process by the human body, and it is impossible to result in vitamin D3 overdose. The second source is through diet supplements. Human body cannot regulate this source of intake well, and vitamin D3 overdose and subsequent toxicity could occur. Interestingly, vitamin D3 itself is not the biologically active form. It must be first hydroxylated at the C25 position in the liver to produce 25-hydroxyvitamin D3 (25(OH)D3), followed by a second hydroxylation at the C1 position in the kidney or by monocyte-macrophages in the immune system to produce the biologically active form 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) (Figure 1). 1,25(OH)2D3 binds to the Vitamin D Receptor (VDR) which ultimately lead to its various biological functions (Figure 1).

Vitamin D and UV exposure in chronic kidney disease

With loss of renal function and decreasing glomerula filtration rate the serum levels of 25-hydroxyvitamin D [25(OH)D] as well as 1,25-dihydroxyvitamin D [1,25 (OH)2 D] often decrease simultaneously. In representative groups of German patients on renal replacement therapy (hemodialysis, peritoneal dialysis, kidney transplantation) our group retrospectively analyzed the vitamin D status over a period of 12 y (1995‒2006). Only 11% of patients had a serum level of 25(OH)D that was > 30 ng/ml, more than 70% had a level of 25(OH)D < 20 ng/ml. In clinical trials we used sun-simulating artificial lamps to produce vitamin D3 in the skin. Partial-body irradiation (15% of body surface) was used during the routine hemodialysis treatment. Whole-body UV exposure was done in a standing position three times a week before the hemodialysis treatment. With both procedures we observed an increase of the serum level of 25(OH)2D3 by approx. 35–50% over a period of 2‒3 mo, maintenance of trabecular bone mineral density and a normalization of systolic and diastolic blood pressure. Heart rate variability improved during the whole-body radiation intervention period by 20‒25%. Patients who continued the whole-body irradiation regularly two or three times before starting the routine hemodialysis session had maintained normal levels of circulating 25(OH)D3 and of 1,25(OH)2D3. Therefore, from our data it can be recommended that intermittent suberythemal UVB exposure with a sun-simulation spectrum is effective to treat and/or protect against vitamin D deficiency in chronic and end-stage kidney disease patients.

Vitamin D

Low levels of 25-hydroxyvitamin D have been documented among inhabitants of the wider Middle East and North African countries. Sunlight has long been recognized as a major provider of vitamin D. In this study we aimed to determine the optimum time for sun exposure in the Central region of Riyadh, Saudi Arabia. Ampoules containing 7-dehydrocholesterol in ethanol were exposed to sunlight every hour starting from sunrise until sunset in July and December. Our results demonstrated that the time of the day has a major influence in vitamin D production. In this study, summer production of previtamin D3 was observed to occur between 8:00 PM to 4:00 PM with peak hours between 10:00 AM to 12:00 PM. During wintertime however, the conversion began later at around 9:30 AM and ended sooner at 2:00 PM, with peak hours at 10:00 AM to 12 noon. In conclusion, the optimum time to get sun exposure for vitamin D3 production in Riyadh, during summer is from 9:00 AM and before 10:30 AM, as well as after 2:00 PM until 3:00 PM, while during winter it’s from 10:00 AM until 2:00 PM. These times are important on a public health perspective, as it’s free, relatively safe and the most enjoyable. This strategy is a highly efficacious way for improving the vitamin D status for children and adults and preventing vitamin D deficiency.

Effects of vitamin D on antigen-specific and non-antigen-specific immune modulation: relevance for type 1 diabetes

Vitamin D is a fat-soluble precursor of the circulating 25-hydroxyvitamin D₃ (25(OH)D₃)which can be converted by the 1α-hydroxylase (1α(OH)ase) enzyme into the bioactive hormonal metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), generally known to promote bone mineralization through its ability to enhance calcium absorption from the gut. Importantly, in humans, vitamin D is mainly derived from endogenous production of vitamin D₃ from ultraviolet (UV) radiation exposure to the skin while a small part (<10%) is obtained via dietary intake of dairy products and fatty fish (1). Taking these factors into account, geographic distribution and seasonality, skin pigmentation, age, and lifestyle may predispose certain populations to be at a higher risk of developing vitamin D insufficiency or deficiency (2). The first valid reports correlating the importance of an adequate vitamin D status to optimal human health originate from the early part of the 20th century, when vitamin D was described to prevent and treat the bone disease rickets. Since then, the findings that vitamin D receptors (VDR) are present in many body tissues and that vitamin D metabolizing enzymes can be found in various cells outside the kidney, including the intestine, prostate, immune cells, and within the skin itself (reviewed in reference 3), have revolutionized the vitamin D business. In this review, we will mainly focus on vitamin D as a component of immune regulation and on the role of vitamin D in antigen-specific and non-specific therapies with potential relevance for type 1 diabetes (T1D).

The statin D-lemma

The statin D-lemma

Photoisomerization of Alfa Calcidol by a Sensitized Quantum Chain Reaction†

The production of vitamin D3 is a pharmaceutically relevant process, producing high added-value products. Precursors are extracts from vegetal origin but bearing mainly an E geometry in the 5,6 double bond. The synthesis of vitamin D3 (5-E-α-calcidol) with the correct Z stereochemistry in the 5,6 double bond from the E isomer using anthracene and triethylamine (TEA) as the sensitizer system was studied from the kinetic and mechanistic point of view. The sensitized isomerization of E-calcidol by irradiation of anthracene takes place only in deoxygenated solution and yields the Z isomer in ca 5% yield in the photostationary state. When TEA is added to the system, the E-Z reaction is not inhibited by oxygen any more, the quantum yield of photoisomerization to the Z isomer grows linearly with the concentration of E-calcidol, while conversions higher than 95% to the Z isomer are reached in the photostationary state and E-Z quantum yields as high as 45 at [E-calcidol] = 25 mM are reached. If TEA is replaced by 1,4-diazabicyclo[2.2.2]octane, the reaction rate drops to one-third at the same amine concentration. The observations can be explained by a quantum chain reaction mechanism. The high conversion achieved eliminates the need of isomer separation.

Variability of solar UV-B irradiance: in situ monitoring and model calculation of the vitamin D synthetic capacity of sunlight

The prediction of the biological effects of solar radiation on human health, in particular involving terrestrial level of solar ultraviolet (UV) radiation, requires the development of an adequate methodological strategy for remote sensing. To date, it is well understood that, in appropriate doses, UV radiation is beneficial for people, specifically due to the production of vitamin D3 in the skin from its precursor 7-dehydrocholesterol. But as far as excessive UV exposure causes acute and chronic health effects, in most cases biological activity of solar UV radiation is calculated by weighting solar UV spectra with International Commission on Illumination (CIE) erythemal action spectrum. Yet the beneficial vitamin D synthetic capacity of sunlight cannot be correctly estimated in this way because of the significant difference between the erythemic and vitamin D synthesis action spectra. With due regard to the essential role of vitamin D3 for human health, in this article we examine the possibility of simplified estimation in situ of provitamin D3 photoconversion into previtamin D3 from the UV absorption spectra of an in vitro model of vitamin D synthesis upon exposure to sunlight. A large-scale linear correlation (R = 0.99) was found on a clear summer day between the concentration of accumulated previtamin D3 and maximum absorbance decline in the initial provitamin D3 absorption spectrum. However, long-term observations showed a poorer (R = 0.77) correlation, and a source of ambiguity of such indirect estimation of previtamin D3 concentration is discussed in detail. In addition, we propose a reliable algorithm for the direct calculation of previtamin D3 accumulation using solar UV spectra as input data to the reaction model of previtamin D photosynthesis and demonstrate the critical dependence of previtamin D3 accumulation on stratospheric ozone, season, latitude and cloudiness. The comparison of experimental and simulation data conforms to recent findings on Europe's darker atmosphere in the UV-B and implicates the practical certainty of the presented algorithm for the calculation of the vitamin D synthetic capacity from the remotely sensed solar spectra.

Is it time to trial vitamin D supplements for the prevention of schizophrenia?

Is it time to trial vitamin D supplements for the prevention of schizophrenia?

Worldwide status of vitamin D nutrition

The vitamin D status depends on the production of vitamin D3 in the skin under the influence of ultraviolet radiation and vitamin D intake through the diet or vitamin D supplements. The serum 25-hydroxyvitamin D (25(OH)D) concentration is the parameter of choice for the assessment of vitamin D status. Low serum levels of calcium and phosphate and an elevated level of alkaline phosphatase can also point to vitamin D deficiency. Usually, between 50% and 90% of vitamin D in the body is coming from the production in the skin and the remainder is from the diet. The production of vitamin D3 in the skin depends on sunshine exposure, latitude, skin-covering clothes, the use of sun block and skin pigmentation. In general, serum 25(OH)D is lower with higher latitudes and with darker skin types, but there are exceptions. Vitamin D deficiency (serum 25(OH)D < 25 nmol/l) is highly prevalent in India and China while vitamin D status is better in Japan and South-East Asia. Vitamin D deficiency is very common in the Middle-East and there is a relationship with skin covering clothes and staying outside of the sun. A poor to moderate vitamin D status is also common in Africa, probably caused by the dark skin types and cultural habits of staying outside of the sunshine. Vitamin D status is much better in North America where vitamin D deficiency is uncommon but vitamin D insufficiency (serum 25(OH)D between 25 and 50 nmol/l) is still common. In the United States and Canada milk is usually supplemented with vitamin D and the use of vitamin supplements is relatively common. Vitamin D status in Latin America usually is reasonable but there are exceptions and vitamin D insufficiency still occurs quite often. In Australia and New Zealand a poor vitamin D status was seen in the elderly who were often vitamin D deficient and also in immigrants from Asia. Vitamin D deficiency also occurred in children when the mother was vitamin D deficient. Within Europe, vitamin D status usually is better in the Nordic countries than around the Mediterranean. This may be due to a lighter skin and sun seeking behaviour and a high consumption of cod liver oil in the Northern countries while in Southern Europe people stay out of the sunshine and have a somewhat darker skin. A very poor vitamin D status was observed in non-western immigrants, especially in pregnant women. In conclusion, vitamin D deficiency and insufficiency are globally still very common especially in risk groups such as young children, pregnant women, elderly and immigrants.