Ultraviolet radiation and effects on humans: the paradigm of maternal vitamin D production during pregnancy.

Current evidence indicates that neonates born of mothers with vitamin D deficiency during pregnancy have greater risk for developing hypocalcemia, rickets and extra-skeletal disorders. Despite the classic knowledge that ultraviolet-B (UVB) exposure is the most efficient way for a future mother to obtain optimal vitamin D concentrations, no current consensus or clinical recommendations exist regarding the duration and timing of UVB exposure for pregnant women. This article offers a narrative review of available data regarding how UVB exposure affects maternal vitamin D production during pregnancy, along with a discourse on clinical implications of this public health issue. Future studies would benefit from adopting UVB exposure estimates to recommend appropriate UVB exposure to pregnant women. Doing so could provide a more holistic and practical approach in managing maternal hypovitaminosis D during pregnancy.

Vitamin D and gonadal function in men: a potential inverse U-shaped association?

Accumulating evidence from animal and human studies suggests that vitamin D, apart from its regulatory effects on musculoskeletal health, is involved in reproductive function in both genders. The basis of the interplay between vitamin D and reproduction lays on the presence of both vitamin D receptor (VDR) and 1α-hydroxylase (CYP27B1) enzyme in reproductive organs. In males, VDR are present in testis, epididymis, prostate, and seminal vesicles. In Sertoli cells, whose secretory activities are ion channel-dependent, vitamin D has been shown to stimulate calcium uptake through a nuclear receptor activity. Epidemiological studies support a positive association between serum 25-hydroxy-vitamin D [25(OH)D] concentrations and sperm motility in both fertile and infertile men In addition, large multi-center, cross-sectional studies from Europe and USA have shown positive, linear association between 25(OH)D and androgen concentrations. On the contrary, there are studies that support an inverse U-shaped association, that is, men with both low and high 25(OH)D concentrations demonstrate poorer gonadal function compared with those with intermediate concentrations. Given the rapid increase in over-the-counter use of vitamin D supplements by men that anticipate advantageous health outcomes, the aim of the present commentary is to provide an overview of the studies that present either U-shaped or linear association between 25(OH)D concentrations and male gonadal function.

Hypovitaminosis D in pregnancy in the Mediterranean region: a systematic review.

Despite high levels of sunshine, maternal hypovitaminosis D during pregnancy is prevalent in the Mediterranean region. The aim of this study is to systematically review trials that investigated vitamin D concentrations during pregnancy in this region, in order to determine predictors of hypovitaminosis D and explain this phenomenon. After applying inclusion/exclusion criteria, 15 studies were entered into the systematic review involving 2649 pregnant women and 820 neonates. The main outcome was maternal vitamin D status, assessed by serum 25-hydroxy-vitamin D (25(OH)D) concentrations. Possible predictors of the outcome included maternal age, body mass index (BMI), race, socioeconomic status, skin type, gestational age, sun exposure, calcium and vitamin D intake and supplementation, smoking status, parity and season of delivery. Studies differed widely in vitamin D deficiency criteria, method of measurement and outcomes. The prevalence of vitamin D insufficiency ranges from 9.3 to 41.4%, whereas that of vitamin D deficiency from 22.7 to 90.3%. A positive association with 25(OH)D concentrations exists for light skin color, white race, uncovered dressing pattern, maternal vitamin D supplementation and season of gestation (spring/summer). An inverse association exists for BMI and gestational age, whereas data for smoking and socioeconomic status are controversial. We concluded that vitamin D deficiency in pregnancy seems to be quite common, even in the Mediterranean region. Racial, social and cultural habits, as well as the absence of preventive supplementation/dietary strategies, seem to negate the benefits of sun exposure.

Vitamin D during pregnancy: why observational studies suggest deficiency and interventional studies show no improvement in clinical outcomes? A narrative review.

A considerable number of studies have examined vitamin D status during pregnancy. Although data from observational studies denote vitamin D hypovitaminosis (deficiency or insufficiency) during pregnancy is associated with a plethora of adverse maternal and neonatal outcomes, data from interventional (supplementation) trials fail to reveal a significant impact on maternal and offspring health. The aim of this narrative review was to critically appraise the methodology of the most representative published randomized controlled trials in an attempt to explain the difference between observational and supplementation results. We found that this difference could be attributed to a variety of factors, namely: (i) study design (lack of a specific outcome in conjunction with timing of supplementation, enrolment of participants with heterogeneous vitamin D status); (ii) pitfalls in the interpretation of vitamin D equilibrium (lack of determination of plasma half-life); (iii) supplementation regimen (administration of a wide range of regimens, in terms of dose, bolus and form); (iv) geographical characteristics (vitamin D needs could vary significantly within a country, particularly in areas with a wide range of latitude gradient); (v) adaptations of vitamin D metabolism during pregnancy (vitamin D and calcium equilibrium are changed during pregnancy compared with the non-pregnant state) and (vi) supplementation of populations with low baseline 25(OH)D values would likely manifest beneficial effects. All these parameters should be taken into consideration in the design of future vitamin D supplementation trials.

Vitamin D status during pregnancy: time for a more unified approach beyond borders?

Maternal hypovitaminosis D during pregnancy has been associated with a plethora of adverse health effects on the offspring. Maternal vitamin D status during pregnancy is affected by local climatic conditions. The aim of this article was to report on difficulties related to the heterogeneity of studies available in current literature on vitamin D status during pregnancy and discuss the incorporation of geophysical data in future studies, in an attempt to optimize their design and facilitate their interpretation. We focused on current vitamin D trials during pregnancy and their association with local regional climatic condition in geographical regions such as the Mediterranean basin based on our perspective on the field. Conduction of studies from areas with similar geophysical conditions is necessary, in order to extend our knowledge with respect to the question of which populations and under which circumstances would benefit most from vitamin D supplementation. Future vitamin D studies could benefit from the adoption of a unified concept minimizing these variations by selecting populations residing in areas with similar geophysical conditions adjusting also for their social and dietary habits.

Maternal vitamin D status in pregnancy and offspring bone development: the unmet needs of vitamin D era.

Data from animal and human studies implicate maternal vitamin D deficiency during pregnancy as a significant risk factor for several adverse outcomes affecting maternal, fetal, and child health. The possible associations of maternal vitamin D status and offspring bone development comprise a significant public health issue. Evidence from randomized trials regarding maternal vitamin D supplementation for optimization of offspring bone mass is lacking. In the same field, data from observational studies suggest that vitamin D supplementation is not indicated. Conversely, supplementation studies provided evidence that vitamin D has beneficial effects on neonatal calcium homeostasis. Nevertheless, a series of issues, such as technical difficulties of current vitamin D assays and functional interplay among vitamin D analytes, prohibit arrival at safe conclusions. Future studies would benefit from adoption of a gold standard assay, which would unravel the functions of vitamin D analytes. This narrative review summarizes and discusses data from both observational and supplementation studies regarding maternal vitamin D status during pregnancy and offspring bone development.

Hormonal replacement therapy in ovarian cancer survivors: a survey among Greek gynecologists.

PURPOSE OF INVESTIGATION: In this survey we evaluated the prescription attitude of Greek gynecologists towards hormone replacement therapy (HRT) for ovarian cancer survivors. METHODS: An anonymous questionnaire was sent to 900 members of the Hellenic Society of Obstetrics and Gynecology presenting a hypothetical case of an ovarian cancer survivor with indications for HRT followed by a series of relevant questions. RESULTS: Two hundred and ninety-eight responses were analyzed with regards to age, gender and practice setting. HRT would be prescribed by 48% of Greek gynecologists; regarding type of regimen, 60% would prescribe tibolone, 19% estrogen alone and 21% estrogen plus progestagen. In contrast, 52% of Greek gynecologists would not prescribe HRT due to the fear of ovarian cancer relapse (83%), or the development of breast cancer (6%), or both cancers (9%); among them, 21% would alternatively prescribe CNS medications, 9% SERMs, phyto-estrogens or bisphosphonates, while the remaining 70% would not prescribe anything. CONCLUSIONS: One out of two Greek gynecologists would prescribe HRT in ovarian cancer survivors. An alternative therapy, mainly CNS medications, would be suggested by 21% of the opposers.

Hormone therapy for postmenopausal endometrial cancer survivors: a survey among Greek obstetricians-gynaecologists.

PURPOSE OF INVESTIGATION: In this study we evaluated the prescription attitude of Greek obstetricians-gynaecologists towards hormone replacement therapy (HRT) for endometrial cancer survivors. METHODS: An anonymous questionnaire was sent to 900 members of the Hellenic Society of Obstetrics and Gynaecology, presenting a hypothetical case of an endometrial cancer survivor with indications for HRT, followed by a series of relevant questions. RESULTS: Three hundred and three valid responses were received and analysed according to age, gender and practice setting. HRT would be prescribed by 30.4% of gynaecologists; as far as type of regimen is concerned, 67.4% would prescribe tibolone, 22.8% estrogen-only and 9.8% estrogen plus progestagen. In contrast, 69.6% would not prescribe HRT due to the fear of endometrial cancer recurrence (88.2%), development of breast cancer (2.8%) or both (4.7%); among them, 28.4% would prescribe central nervous system (CNS) medications, selective estrogen receptor modulators (SERMs), phyto-oestrogens or biphosphonates, as alternates. CONCLUSIONS: One out of three Greek gynaecologists would prescribe HRT to endometrial cancer survivors. Alternative therapies, mainly CNS medications, would be suggested by the opposers.