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25-hydroxycholecalciferol (25-OHD 3 ) formed via hepatic hydroxylation from vitamin D, cholecalciferol, represents the precursor of the biologically active vitamin D hormone, 1,25-dihydroxyvitamin D. Due to a higher absorption rate and the omission of one hydroxylation, dietary supplementation of 25-OHD 3 instead of vitamin D 3 is considered to be more efficient as plasma concentrations of 25-OHD 3 are increased more pronounced. The present review summarises studies investigating potential beneficial effects on mineral homeostasis, bone metabolism, health status and performance in sows, piglets and fattening pigs. Results are inconsistent. While most studies could not demonstrate any or only a slight impact of partial or total replacement of vitamin D 3 by 25-OHD 3 , some experiments indicated that 25-OHD 3 might alter physiological processes when animals are challenged, for example, by a restricted mineral supply., (© 2022 The Authors. Journal of Animal Physiology and Animal Nutrition published by Wiley-VCH GmbH.)

EFSA was asked by the European Commission to provide scientific assistance with respect to the EFSA adopted scientific opinion on 'Safety of calcidiol monohydrate produced by chemical synthesis as a novel food pursuant to Regulation (EU) 2015/2283', including its bioavailability as a metabolite of vitamin D3 when added for nutritional purposes to food supplements. On 5 July 2023, EFSA adopted the 'Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate'. This opinion concerns an updated exposure assessment for vitamin D and proposes a conversion factor for calcidiol monohydrate into vitamin D3 of 2.5 for labelling purposes. In addition, in reference to the EFSA opinion on the safety of calcidiol monohydrate, the Commission had received a letter from the pharmaceutical company EirGen Pharma Ltd requesting a revision of this opinion based on new data concerning calcidiol. Based on the information and data considered in this scientific technical report, EFSA concludes that the novel food calcidiol monohydrate proposed for use in food supplements is a bioavailable source of the biologically active metabolite of vitamin D, i.e. 1,25‐dihydroxyvitamin D, that a conversion factor of 2.5 reflects the relative bioavailability of calcidiol vs vitamin D3 under the proposed conditions of use and use levels, and that it is safe under the proposed conditions of use and use levels, i.e. up to 10 μg/day for children ≥ 11 years old and adults, including pregnant and lactating women, and up to 5 μg/day for children 3–10 years of age. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to evaluate the effect of vitamin D deficiency (VDD) on orthodontic tooth movement (OTM), retention, and relapse and to assess the effect of systemic administration of vitamin D (VD) in a rat model. Materials and Methods: A total of 32 male Wistar rats were divided into two groups, a control group of 11 rats and an experimental group of 21 rats with VDD, after enhancement using a custom diet. Of the VDD group, 11 rats were supplemented with systemic vitamin D3 and categorized as vitamin (VD supplement [VDS]) groups. The VDS group received 40,000 IU/kg via intramuscular injection on Days 1 and 15 of the orthodontic treatment period. A modified orthodontic appliance was fitted to apply 0.5 N of force to move the maxillary right first molars mesially for 14 days, followed by retention and relapse periods for 7 days. Space created during OTM was measured and reassessed after the retention and relapse periods. The relapse ratio was estimated, and histomorphometric analysis was performed to assess the number of osteoblasts, osteoclast bone cells, and bone area. Results: A significant increase in the relapse ratio and a reduction in osteoblast cells and bone area were observed in the VDD group. By contrast, the amount of tooth movement was significantly higher together with osteoblast cells and bone marrow in VDS with a significant reduction in relapse ratio. Conclusion: VDD was associated with a significant reduction in osteoblast cell count and total bone area in addition to a significant increase in relapse ratio. Routine screening of VD may be beneficial before commencing orthodontic treatment. [ABSTRACT FROM AUTHOR]

Background: Vitamin D is a micronutrient that plays a critical role in human health; vitamin D has both skeletal and extra skeletal functions. Vitamin D is essential for maintenance of bone and musculoskeletal health. It plays a crucial role in calcium and phosphate homeostasis as well as normal bone growth and mineralization. Although vitamin D, which is an essential fat-soluble nutrient, was first identified as a vitamin, it is now considered a prohormone and is unique to other nutrients because it can be synthesized in the skin through exposure to sunlight. Cutaneous synthesis of vitamin D3 requires the exposure of ultra-violet B rays at wavelength of 290 -315 nm. Once formed, vitamin D3 exits the cutaneous tissue and enters the circulation. Vitamin D is essential for maintenance of bone and musculoskeletal health. It plays a crucial role in calcium and phosphate homeostasis as well as normal bone growth and mineralization. 1,25(OH)2D has been shown to have prodifferentiation and antiproliferation effects on the keratinocyte, anti-tumergenic and anti-metastatic activities on several types of cancer cells, immune-modulatory effects on macrophages and on activated T and B lymphocytes, effects on skeletal muscle function, and protective effects against cardio-metabolic disorders and pregnancy related complications. Vitamin D hormone has important functions including immunomodulant, anti-inflammatory and anti-infective roles. It acts via monocyte and cell-mediated immunity stimulation, suppression of lymphocyte proliferation, antibody production and cytokine synthesis. [ABSTRACT FROM AUTHOR]

Vitamin D plays crucial roles in calcium absorption, bone metabolism, and immune, neurological and cardiovascular-related functions. In plants, it plays an important role in the form of D2 (ergocalciferol). Intake of vitamin D and its precursors by livestock varies with the specific forage crop, season, presence of fungal infestation and geographic location. Oral supplementation with vitamin D3 is highly effective at raising plasma and tissue levels of vitamin D and its metabolites in livestock. The vitamin D3 content varies in different cuts of meat, with higher levels typically correlated with increased fat content, although the same does not hold true for 25(OH)D3. The highest vitamin D3 content in meat is typically found in pork (mean content of 2.5 µg/kg) and chicken (mean of 2.4 µg/kg), followed by beef (mean of 2.2 µg/kg), with lamb containing the least (mean of 1.1 µg/kg). Storage and processing generally have minimal impact on the content of vitamin D or its metabolites in meat, aside from an increase on an as-is basis resulting from moisture loss. Due to their widespread availability and consumption, meat products appear to be a significant source of vitamin D and its hydroxylated forms for much of the global population. [ABSTRACT FROM AUTHOR]

Recent studies show a correlation between the content of vitamin D3 in the human body and the severity of COVID19. Part of the world's population is deficient in vitamin D3. The solution to this problem is possible by the development and inclusion of foodstuffs fortified with vitamin D in diets. The aim of this study was to develop a D3 -fortified sour cream dessert using an emulsion system as a vitamin D delivery system. Commercially available raw materials: vitamin D3 powder, sodium carboxymethylcellulose, skimmed milk powder, and sunflower oil were used to create a vitamin D-fortified emulsion. The latter is used in the technology of sour cream dessert production. The emulsion microstructure and stability were investigated using rheology and dynamic light scattering methods. The content of vitamin D3 was determined by coulometric titration and spectroscopy. Experimentally determined data on the viscosity of emulsions indicate the pseudoplastic behavior of the flow. The use of a structural approach (Casson model) made it possible to determine the emulsion viscosity parameters, which can be used as a quantitative criterion for emulsion stability. This conclusion was confirmed by microstructural data on distribution size of droplets volume of emulsion. Amount of vitamin D in the emulsion and dessert was 1.96 ± 0.22 µg/g (97.8 % of the added amount) and 0.019±0,005 µg/g, respectively. Using the developed stable emulsion as a vitamin D delivery system, a technology for the production of a dessert based on sour cream fortified with vitamin D3 was proposed. [ABSTRACT FROM AUTHOR]

Nutrient D might have a useful job in male propagation. The male regenerative framework is an objective tissue for nutrient D. In this study, the effects of vitamin D supplementation and calcium on sperm boundaries, original and serum levels of oxidative pressure, and serum endocrine variables in asthenospermia barren males will be evaluated. Study was conducted in Baquba city, Diyala Governorate, Iraq, AL-Batool teaching hospital. The samples were taken to assess the seminal fluid parameters This study showed that treatment with calcium and vitamin D increased the level of movement of sperms, where they were before treatment introduction VOL (4.375) and after the treatment was (5.571). Also, the sperm and Grade -A before treatment was (4.851, 6.751). The study noticed an increased in their percentage after using the treatment where it was (5.262, 8.723). [ABSTRACT FROM AUTHOR]

Effect of low plasma vitamin D on metabolic pathways and metabolites has been a matter of concern by many experimental and epidemiological studies. The Potential relationship between plasma vitamin D and serum uric acid level is still under further studies. Many reports were emerged recently suggesting that patients with low plasma vitamin D tend to be with higher level of blood uric acid level compared with those with adequate level of plasma vitamin D. Our data indicates a gross inverse relationship between plasma vitamin D and the level of serum uric acid in adult males and females individuals living in Duhok city-Iraq. Most of the involved participants (more than 75%) were found with insufficiency and deficiency of vitamin D3. Around 20% were with sufficient amount of plasma vitamin D3. Those with insufficient and/or deficient amount of plasma vitamin D had greater levels of serum uric acid. Since, more than 35% of the participants with plasma vitamin D3 less than 10ng/ml and with greater amount of serum uric acid. Interestingly, the data of the current study were analyzed together, we found a significant inverse relationship between plasma levels of vitamin D3 and serum uric acid levels (P<0.0040). [ABSTRACT FROM AUTHOR]

Background: A high prevalence of vitamin D insufficiency/deficiency, which may impact on health and training ability, is evident among athletes worldwide. This observational study investigated the vitamin D status of elite Irish athletes and determined the effect of wintertime supplementation on status. Methods: Serum 25-hydroxyvitamin D [25(OH)D], calcium, and plasma parathyroid hormone were analyzed in elite athletes in November 2010 (17 boxers, 33 paralympians) or March 2011 (34 Gaelic Athletic Association [GAA] players). A subset of boxers and paralympians (n = 27) were supplemented during the winter months with either 5,000 IU vitamin D3/d for 10–12 weeks or 50,000 IU on one or two occasions. Biochemical analysis was repeated following supplementation. Results: Median 25(OH)D of all athletes at baseline was 48.4 nmol/L. Vitamin D insufficiency/deficiency (serum 25(OH)D <50 nmol/L) was particularly evident among GAA players (94%) due to month of sampling. Wintertime supplementation (all doses) significantly increased 25(OH)D (median 62.8 nmol/L at baseline vs. 71.1 nmol/L in April or May; p = .001) and corrected any insufficiencies/deficiencies in this subset of athletes. In contrast, 25(OH)D significantly decreased in those that did not receive a vitamin D supplement, with 74% of athletes classed as vitamin D insufficient/deficient after winter, compared with only 35% at baseline. Conclusions: This study has highlighted a high prevalence of vitamin D insufficiency/deficiency among elite Irish athletes and demonstrated that wintertime vitamin D3 supplementation is an appropriate regimen to ensure vitamin D sufficiency in athletes during winter and early spring. [ABSTRACT FROM AUTHOR]

Introduction: Sleep disorders are a common condition globally. Vitamin D receptors are present on cells in several regions of the brain. It is possible that vitamin D status may affect brain function, including sleep patterns. We aimed to evaluate the 1,500 IU of Nano‐encapsulated vitamin D fortified in dairy products on the symptoms of insomnia and associated improvement of quality of life. Methods: A case series was undertaken as part of the Survey of ultraviolent intake by nutritional approach project. Subjects enrolled among adults with abdominal obesity. Twenty‐nine subjects with insomnia were selected according to the results of Insomnia Severity Index questionnaire and quality of life using a Short Form Health Survey (SF‐36) questionnaire. Subjects were allocated to four groups: low‐fat milk fortified by 1,500 IU vitamin D3 (n = 8), simple milk (n = 8), low‐fat yogurt fortified by 1,500 IU vitamin D3 (n = 7), and simple yogurt (n = 6) and were treated for 10 weeks. Results: The insomnia score improved after the intervention in the group receiving vitamin D fortified milk compared to group receiving unfortified milk (p <.001). There were no significant differences between the two groups taking yogurt (fortified vs. unfortified). Comparison of quality of life scores between baseline and after intervention indicated significant improvements in both fortified and simple milk groups (p =.002 and p =.03, respectively); but no differences were found in the groups taking yogurt. Conclusion: Fortified low‐fat milk containing 1,500 IU vitamin D3 can improve insomnia symptoms and subsequently quality of life. Trial registration number: IRCT20101130005280N27, www.IRCT.ir. [ABSTRACT FROM AUTHOR]

Due to the presence of receptors in the cells of numerous body tissues, vitamin D is associated with several physiological functions that go beyond calcium and phosphorus homoeostasis and control of bone metabolism in the body. In humans, several studies have associated lower vitamin D concentrations with numerous diseases, such as cancer, heart disease, autoimmune diseases and infectious diseases, and also with an increase in the total mortality rate of the population. Recently, this nutrient started to gain importance in veterinary medicine, and several articles have shown a correlation between low vitamin D status and diseases unrelated to bone metabolism. The present review aims to highlight the recent publications that investigated this relationship, bringing the evidence that exists so far in dogs and cats. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate the effects of supplementing both phytase and 25‐hydroxyvitamin D3 (25‐OH‐D₃) on pig performance, nutrient digestibility, carcass characteristics, bone parameters and pork quality in finisher pigs. The experimental design was a 2 × 2 factorial comprising of four dietary treatments. One hundred and twenty pigs (60 male, 60 female) were blocked according to live weight and sex and allocated to the following dietary treatments: low P (4.81 g/kg) diet (basal) (T1); low P diet + phytase (T2); low P diet + 25‐OH‐D₃ (T3) and low P diet + phytase + 25‐OH‐D₃ (T4). Pigs supplemented with phytase had a lower average daily feed intake (ADFI) (2.45 kg vs. 2.59 kg; p < 0.05) and lower feed conversion ratio (FCR) (2.74 kg/kg vs. 2.85 kg/kg; p < 0.05) compared to pigs offered the nonphytase diets. Pigs offered phytase diets had a higher (p < 0.05) coefficient of apparent total tract digestibility (CATTD) of ash, phosphorous (P) and calcium (Ca) compared with pigs offered the nonphytase supplemented diets. Pigs offered the 25‐OH‐D3 diets had a higher CATTD of N and ash. Pigs offered the phytase diets had increased (p < 0.05) bone DM, ash, Ca, P and density compared to the nonphytase diets. There was a significant interaction (p < 0.05) between phytase and 25‐OH‐D3 on cook loss. Pigs offered 25‐OH‐D3 had increased cook loss over the basal diet; however, there was no effect on cook loss when phytase and 25‐OH‐D3 were offered in combination compared to the phytase only diet. Pigs offered 25‐OH‐D3 exhibited higher (p < 0.05) Warner Bratzler shear force values and lower (p < 0.05) pork lightness (L*) surface colorimeter values. In conclusion, there was no benefit to offering a combination of phytase and 25‐OH‐D3 on pig performance, bone parameters or pork quality. [ABSTRACT FROM AUTHOR]

Copyright of Applied Physiology, Nutrition & Metabolism is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vitamin D is the name given to a group of fat-soluble prohormones. Two major forms of Vitamin D that are important to humans are Vitamin D2 or ergocalciferol and Vitamin D3 or cholecalciferol. Vitamin D2 is made naturally by the body when the skin is exposed to ultraviolet radiation (in particular, ultraviolet B [UVB] radiation) in sunlight. Vitamin D2 and Vitamin D3 can also be commercially manufactured. The active form of Vitamin D in the body is 1,25-dihydroxyvitamin D or calcitriol, which can be made from either Vitamin D2 or Vitamin D3. Evidence suggests that Vitamin D helps in the prevention of various cancers such as breast cancer, colorectal cancer, prostate cancer, head and neck cancer, and other cancers. This review article briefs about the role of Vitamin D in the prevention of cancer. [ABSTRACT FROM AUTHOR]

Background: Vitamin D3 deficiency is highly prevalent in the population throughout the world and it's underestimated due to lack of screening tests. It's also associated with numerous diseases, including those characterized by inflammatory processes. Aim of study: The study aims to examine the prevalence of vitamin D3 deficiency among young healthy females in Kerbala province. If we prove the high prevalence of vit D deficiency, we would consider writing a policy to the governmental bodies to start screening for Vitamin D3 deficiency and increase public awareness about this public health problem. Materials and methods: This study was conducted at Al Zahra Medical Center, Kerbala, Iraq. The eligible candidates for this study were randomly selected; they were 305, 129 out of them were excluded due to having various medical issues and a further 96 excluded due to having anaemia; therefore, 80 final healthy subjects included in this study. Subjects selected from the patients and relatives attending the outpatient clinic during the period from Nov, 2015 to June, 2016, age ranged between (18- 50) years. Subjects interviewed and reviewed clinically, body mass index (BMI) calculated, Vitamin D3, creatinine, parathyroid hormone PTH, calcium, Alkaline phosphatase ALP, phosphorus and complete blood count were tested. Results: The results showed that serum vitamin D3 level were significantly decreased in the selected healthy females (18.86 ±9.91 ng /ml). There is a significant differences were detected when the levels of serum Vitamin D3 were compared according to age, body mass index, skin pigmentation and place of residence. Conclusions: There is a significantly low level of serum vitamin D3 in healthy female subjects in holy City of Kerbala province; High prevalence rate of hypovitaminosis is observed in spite of good sun light in Iraq which might attribute to the cultural habit and life style. Wellstructured steps need to be taken by the governing bodies to tackle this health problem through primary and secondary care. Increase public awareness regarding adequate exposure to the sun, increase intake of food rich with vitamin D3 or use supplementations and screening for its deficiency especially in females in childbearing age. [ABSTRACT FROM AUTHOR]

Copyright of Applied Physiology, Nutrition & Metabolism is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The most common forms of vitamin D in human and mouse serum are vitamin D3 and vitamin D2 and their metabolites. The aim of this study is to determine whether diet and sunlight directly affect the circulating concentrations of vitamin D metabolites in a mouse model. We investigated the serum concentrations of eight vitamin D metabolites—vitamin D (vitamin D3 + vitamin D2), 25OHD (25OHD3 + 25OHD2), 1α25(OH)2D (1α25(OH)2D2, and 1α25(OH)2D3)—including their epimer, 3-epi-25OHD (3-epi-25OHD3 and 3-epi-25OHD2), and a bile acid precursor 7alpha-hydroxy-4-cholesten-3-one (7αC4), which is known to cause interference in liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Method: The LC-MS/MS method was validated according to FDA-US guidelines. The validated method was used for the analysis of mouse serum samples. Forty blood samples from mice were collected and divided into three groups. The first group, the DDD mice, were fed a vitamin D-deficient diet (25 IU VD3/kg of diet) and kept in the dark; the second group, the SDD mice, were maintained on a standard-vitamin D diet (1000 IU VD3) and kept in the dark; and the third group, SDL, were fed a standard-vitamin D diet (1000 IU VD3) but kept on a normal light/dark cycle. LC-MS/MS was used for the efficient separation and quantitation of all the analytes. Results: The validated method showed good linearity and specificity. The intraday and interday precision were both <16%, and the accuracy across the assay range was within 100 ± 15%. The recoveries ranged between 75 and 95%. The stability results showed that vitamin D metabolites are not very stable when exposed to continuous freeze–thaw cycles; the variations in concentrations of vitamin D metabolites ranged between 15 and 60%. The overlapping peaks of vitamin D, its epimers, and its isobar (7αC4) were resolved using chromatographic separation. There were significant differences in the concentrations of all metabolites of vitamin D between the DDD and SDL mice. Between the groups SDD (control) and SDL, a significant difference in the concentrations of 3-epi-25OHD was noted, where C3 epimer was about 30% higher in SDL group while no significant differences were noted in the concentrations of vitamin D, 25OHD, 1α25(OH)2D, and 7αC4 between SDD and SDL group. Conclusions: A validated method, combined with a simple extraction technique, for the sensitive LC-MS/MS determination of vitamin D metabolites is described here. The method can eliminate the interferences in LC-MS/MS analysis caused by the overlapping epimer and isobar due to them having the same molecular weights as 25OHD. The validated method was applied to mouse serum samples. It was concluded that a standard-vitamin D diet causes an increase in the proportion of all the vitamin D metabolites and C3 epimers and isobar, while UV light has no pronounced effect on the concentrations of the majority of the vitamin D metabolites except 3-epi-25OHD. Further studies are required to confirm this observation in humans and to investigate the biochemical pathways related to vitamin D's metabolites and their epimers. [ABSTRACT FROM AUTHOR]

Studies on vitamin/hormone D deficiency have received a vast amount of attention in recent years, particularly concerning recommendations, guidelines, and treatments. Moreover, vitamin D's role as a hormone has been confirmed in various enzymatic, metabolic, physiological, and pathophysiological processes related to many organs and systems in the human body. This growing interest is mostly due to the evidence that modest-to-severe vitamin D deficiency is widely prevalent around the world. There is broad agreement that optimal vitamin D status is necessary for bones, muscles, and one's general health, as well as for the efficacy of antiresorptive and anabolic bone-forming treatments. Food supplementation with vitamin D, or the use of vitamin D supplements, are current strategies to improve vitamin D levels and treat deficiency. This article reviews consolidated and emerging concepts about vitamin D/hormone D metabolism, food sources, deficiency, as well as the different vitamin D supplements available, and current recommendations on the proper use of these compounds. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the pharmacokinetic (PK) and safety profile of high-dose vitamin D supplementation, comparing different schedules (daily, weekly, or bi-weekly) in an otherwise healthy vitamin D-deficient population. Methods: Single-center, open-label study on healthy subjects deficient in vitamin D (25 (OH)D < 20 ng/mL), randomized to receive cholecalciferol (DIBASE®, Abiogen Pharma, Italy) using three different schedules: Group A: 10,000 IU/day for eight weeks followed by 1000 IU/day for four weeks; Group B: 50,000 IU/week for 12 weeks, Group C: 100,000 IU/every other week for 12 weeks. Total cumulative doses were: 588,000 IU, 600,000 IU, 600,000 IU. The treatment regimens corresponded to the highest doses allowed for cholecalciferol for the correction of vitamin D deficiency in adults in Italy. Results: mean 25 (OH)D plasma levels significantly increased from baseline 13.5 ± 3.7 ng/mL to peak values of 81.0 ± 15.0 ng/mL in Group A, 63.6 ± 7.9 ng/mL in Group B and 59.4 ± 12 ng/mL in Group C. On day 28, all subjects showed 25 (OH)D levels ≥20 ng/mL and 93.1% had 25 (OH)D levels ≥30 ng/mL. On day 56 and 84, all subjects had 25 (OH)D levels ≥30 ng/mL. No serious adverse events occurred during the study. Conclusions: normalization of 25 (OH)D serum levels was quickly attained with all the studied regimens. A more refracted schedule provided a higher systemic 25 (OH)D exposure. [ABSTRACT FROM AUTHOR]

Vitamin D adequacy is essential for multiple physiologic processes. With limited exposure to sunlight for vitamin D3 synthesis, captive primates are supplemented with vitamin D3 (cholecalciferol). Vitamin D metabolite data from wild primates living indigenously could suggest optimum levels. The purpose of this study was to: 1) to explore whether baboons, a speciose genus whose members have significant exposed skin, coat color variation and wide geographical distribution, mirrors the skin pigmentation‐vitamin D relationship found in humans; 2) compare vitamin D metabolite levels in wild and captive members of the same or similar baboon species; and 3) apply a recently developed method currently used in humans for measuring multiple vitamin D metabolites as a panel to explore if/how these metabolites can inform us on vitamin D sufficiency. Serum samples from males of three baboon species in the wild: Papio anubis (olive baboon, dark exposed skin), P. cynocephalus (yellow baboon, brown exposed skin), and P. hamadryas (hamadryas baboon, pink exposed skin), were compared with vitamin D supplemented captive olive baboons with sun exposure. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) measured vitamin D and its main metabolites. Cholecalciferol, 25 hydroxyvitamin D2&3 (25(OH)D2&3), and 24,25 dihydroxyvitamin D2&3 (24,25(OH)2D2&3), showed significant differences by species. The levels of cholecalciferol due to supplements in the captive olive baboons did not convert to higher 25(OH)D3 while the wild olive baboons exhibited the lowest levels for both cholecalciferol and 25(OH)D3. Further metabolic conversion of 25(OH)D3 to 24,25(OH)2D3 indicated that all baboons had more similar conversion ratios and these were within the same range found for humans that are depicted as having adequate vitamin D levels. This study provided evidence that exposed skin color does influence vitamin D3 levels, with lower levels in darker skinned species, but these differences are eliminated in the downstream metabolite conversion indicating strong regulatory control. [ABSTRACT FROM AUTHOR]