New approaches to vitamin D

Vitamin D and critical illness outcomes

PURPOSE OF REVIEW

Although low vitamin D levels have been shown to be a risk factor for adverse outcomes in critical care, it is not clear to date if supplementation can alter such outcomes in all ICU patients. The focus of vitamin D research now is on interventional trials to identify a critically ill patient subset who may benefit from high-dose vitamin D supplementation.

RECENT FINDINGS

The VITdAL-ICU trial, a randomized, double-blind, placebo-controlled, single center trial of 475 heterogeneous critically ill patients, did not show improvement in hospital length of stay or overall mortality but did demonstrate in a secondary outcome that high-dose oral vitamin D3 improved mortality in patients with severe vitamin D deficiency.

SUMMARY

Vitamin D supplementation may represent a personalized and targeted therapy for critical illness. Vitamin D regulates over 1000 genes in the human genome, and the mechanism of action is influenced by gene polymorphisms and epigenetics. The study of the metabolomics, transcriptomics and epigenetics of vitamin D status and supplementation holds promise generating insights into critical illness outcomes.

Admission vitamin D status is associated with discharge destination in critically ill surgical patients

BACKGROUND

Discharge destination after critical illness is increasingly recognized as a valuable patient-centered outcome. Recently, vitamin D status has been shown to be associated with important outcomes such as length of stay (LOS) and mortality in intensive care unit (ICU) patients. Our goal was to investigate whether vitamin D status on ICU admission is associated with discharge destination.

METHODS

We performed a retrospective analysis from an ongoing prospective cohort study of vitamin D status in critical illness. Patients were recruited from two surgical ICUs at a single teaching hospital in Boston, Massachusetts. All patients had 25-hydroxyvitamin D (25OHD) levels measured within 24 h of ICU admission. Discharge destination was dichotomized as non-home or home. Locally weighted scatterplot smoothing (LOWESS) was used to graph the relationship between 25OHD levels and discharge destination. To investigate the association between 25OHD level and discharge destination, we performed logistic regression analyses, controlling for age, sex, race, body mass index, socioeconomic status, acute physiology and chronic health evaluation II score, need for emergent vs. non-emergent surgery, vitamin D supplementation status, and hospital LOS.

RESULTS

300 patients comprised the analytic cohort. Mean 25OHD level was 19 (standard deviation 8) ng/mL and 41 % of patients had a non-home discharge destination. LOWESS analysis demonstrated a near-inverse linear relationship between vitamin D status and non-home discharge destination to 25OHD levels around 10 ng/mL, with rapid flattening of the curve between levels of 10 and 20 ng/mL. Overall, 25OHD level at the outset of critical illness was inversely associated with non-home discharge destination (adjusted OR, 0.88; 95 % CI 0.82-0.95). When vitamin D status was dichotomized, patients with 25OHD levels <20 ng/mL had an almost 3-fold risk of a non-home discharge destination (adjusted OR, 2.74; 95 % CI 1.23-6.14) compared to patients with 25OHD levels ≥20 ng/mL.

CONCLUSIONS

Our results suggest that vitamin D status may be a modifiable risk factor for non-home discharge destination in surgical ICU patients. Future randomized, controlled trials are needed to determine whether vitamin D supplementation in surgical ICU patients can improve clinical outcomes such as the successful rate of discharge to home after critical illness.

Association of low serum 25-hydroxyvitamin D levels and sepsis in the critically ill

OBJECTIVE

We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with sepsis in the critically ill.

DESIGN

Two-center observational study of patients treated in medical and surgical ICUs.

SETTING

Two hundred nine medical and surgical intensive care beds in two teaching hospitals in Boston, MA.

PATIENTS

Three thousand three hundred eighty-six patients, 18 years old or older, in whom 25-hydroxyvitamin D was measured prior to hospitalization between 1998 and 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

: Preadmission 25-hydroxyvitamin D was categorized as deficiency in 25-hydroxyvitamin D (≤ 15 ng/mL), insufficiency (15-30 ng/mL), and sufficiency (≥ 30 ng/mL). The primary outcome was sepsis as defined by International Classification of Diseases, 9th Edition, Clinical Modification and validated by the 2001 Society of Critical Care Medicine/European Society of Intensive Care Medicine, American College of Chest Physicians, American Thoracic Society, and Surgical Infection Society international sepsis definitions conference guidelines. Logistic regression examined the presence of sepsis 3 days prior to critical care initiation to 7 days after critical care initiation. Adjusted odds ratios were estimated by multivariable logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive for the risk of sepsis. In the full cohort, 25-hydroxyvitamin D deficiency is a significant predictor for the risk of International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Deyo-Charlson index (adjusted odds ratio, 1.51 [95% CI, 1.17-1.94]; p = 0.001) relative to patients with 25-hydroxyvitamin D sufficiency. In a subset of cohort patients enriched for those with International Classification of Diseases, 9th Edition, Clinical Modification-diagnosed sepsis (n = 444), preadmission 25-hydroxyvitamin D deficiency is a significant predictor for the risk of conference guideline-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Acute Physiology and Chronic Health Evaluation II (adjusted odds ratio, 2.05 [95% CI, 1.19-3.52]; p = 0.009) relative to patients with 25-hydroxyvitamin D sufficiency. Furthermore, in cohort patients with International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis (n = 568), the multivariable adjusted risk of 90-day mortality was 1.6-fold higher in those with preadmission 25-hydroxyvitamin D values in the insufficient and deficient range, compared with those with preadmission vitamin D sufficiency (adjusted odds ratio, 1.63 [95% CI, 1.11-2.39]; p = 0.01).

CONCLUSION

25-hydroxyvitamin D deficiency prior to hospital admission is a significant predictor of sepsis in the critically ill. Additionally, patients with sepsis who are not vitamin D sufficient have an increased risk of mortality following critical care initiation.

Association between prehospital vitamin D status and hospital-acquired bloodstream infections

BACKGROUND

Alterations in immune function can predispose patients to nosocomial infections. Few studies have explored potentially modifiable host factors that may improve immune function and decrease risk of hospital-acquired bloodstream infection (HABSI). Vitamin D is a key regulator of innate and adaptive immune systems that may influence host susceptibility to infections.

OBJECTIVE

We investigated the association between prehospital serum 25-hydroxyvitamin D [25(OH)D] concentrations and risk of HABSI.

DESIGN

We performed a retrospective cohort study of 2135 adult patients from 2 Boston teaching hospitals. All patients had 25(OH)D concentrations measured before hospitalization between 1993 and 2010. The main outcome measure was HABSI, which was defined as positive blood cultures from samples drawn 48 h after hospital admission. Coagulase-negative Staphylococcus isolates were not considered to be bloodstream infections. Associations between 25(OH)D groups and HABSI were estimated by using bivariable and multivariable logistic regression models. Adjusted ORs were estimated with the inclusion of covariate terms thought to plausibly interact with both 25(OH)D concentration and HABSI.

RESULTS

Compared with patients with 25(OH)D concentrations ≥30 ng/mL, patients with concentrations <30 ng/mL had higher odds of HABSI. For 25(OH)D concentrations <10 ng/mL, the OR was 2.33 (95% CI: 1.45, 3.74); for 25(OH)D concentrations from 10 to 19.9 ng/mL, the OR was 1.60 (95% CI: 1.04, 2.46); and for 25(OH)D concentrations from 20 to 29.9 ng/mL, the OR was 1.13 (95% CI: 0.69, 1.84). After adjustment for age, sex, race (nonwhite compared with white), patient type (medical compared with surgical), and Deyo-Charlson index, the ORs of HABSI were 1.95 (95% CI: 1.22, 3.12), 1.36 (95% CI: 0.89, 2.07), and 0.98 (95% CI: 0.60, 1.62), respectively.

CONCLUSIONS

The analysis of 2135 adult patients showed that 25(OH)D concentrations <10 ng/mL before hospitalization were associated with significantly increased odds of developing HABSI. These data support the initiation of randomized trials to test the role of vitamin D supplementation in HABSI prevention.

Association of low serum 25-hydroxyvitamin D levels and acute kidney injury in the critically ill

OBJECTIVE

Given the importance of inflammation in acute kidney injury and the relationship between vitamin D and inflammation, we sought to elucidate the effect of vitamin D on acute kidney injury. We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with acute kidney injury in the critically ill.

DESIGN

Two-center observational study of patients treated in medical and surgical intensive care units.

SETTING

Two hundred nine medical and surgical intensive care beds in two teaching hospitals in Boston, Massachusetts.

PATIENTS

Two thousand seventy-five patients, aged ≥ 18 yrs, in whom serum 25-hydroxyvitamin D was measured prior to hospitalization between 1998 and 2009.

INTERVENTIONS

: None.

MEASUREMENTS AND MAIN RESULTS

The exposure of interest was preadmission serum 25-hydroxyvitamin D and categorized a priori as deficiency (25-hydroxyvitamin D <15 ng/mL), insufficiency (25-hydroxyvitamin D 15-30 ng/mL), or sufficiency (25-hydroxyvitamin D ≥ 30 ng/mL). The primary outcome was acute kidney injury defined as meeting Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) Injury or Failure criteria. Logistic regression examined the RIFLE criteria outcome. Adjusted odds ratios were estimated by multivariate logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive of acute kidney injury. Patients with 25-hydroxyvitamin D deficiency have an odds ratio for acute kidney injury of 1.73 (95% confidence interval 1.30-2.30; p < .0001) relative to patients with 25-hydroxyvitamin D sufficiency. 25-Hydroxyvitamin D deficiency remains a significant predictor of acute kidney injury following multivariable adjustment (adjusted odds ratio 1.50; 95% confidence interval 1.42-2.24; p < .0001). Patients with 25-hydroxyvitamin D insufficiency have an odds ratio for acute kidney injury of 1.49 (95% confidence interval 1.15-1.94; p = .003) and an adjusted odds ratio of 1.23 (95% confidence interval 1.12-1.72; p = .003) relative to patients with 25-hydroxyvitamin D sufficiency. In addition, preadmission 25-hydroxyvitamin D deficiency is predictive of mortality. Patients with 25-hydroxyvitamin D insufficiency have an odds ratio for 30-day mortality of 1.60 (95% confidence interval 1.18-2.17; p = .003) and an adjusted odds ratio of 1.61 (95% confidence interval 1.06-1.57; p = .004) relative to patients with 25-hydroxyvitamin D sufficiency.

CONCLUSION

Deficiency of 25-hydroxyvitamin D prior to hospital admission is a significant predictor of acute kidney injury and mortality in a critically ill patient population.

Fat-soluble vitamins and atopic disease: what is the evidence?

The prevalence of asthma and other atopic disorders continues to increase worldwide. Examination of the epidemiologic patterns has revealed that this rise has occurred primarily in western, industrialised countries and countries transitioning to this lifestyle. While many changes have occurred in human populations over the years, it has been hypothesised that some of the relevant changes that have led to the rise in asthma and atopic disorders have been the changes from a traditional diet to a more western diet consisting of decreased intake of fruits and vegetables (sources of antioxidant vitamins and carotenoids) leading to decreased intakes of vitamins E and A, and a decrease in sun exposure (e.g. greater time spent indoors and heavy use of sunscreen) leading to decreased circulating levels of vitamin D. This review will examine the evidence for an effect of fat-soluble vitamins (vitamins A, D and K) on the development and severity of asthma and allergies. While observational studies suggest that these vitamins may play a salutary role in asthma and allergies, large, well-designed clinical trials are lacking. Of the fat-soluble vitamins, vitamin D holds great promise as an agent for primary and secondary prevention of disease. Ongoing clinical trials will help determine whether results of observational studies can be applied to the clinical setting.

Childhood asthma may be a consequence of vitamin D deficiency

PURPOSE OF REVIEW

Vitamin D deficiency has been rediscovered as a public-health problem worldwide. It has been postulated that vitamin D deficiency may explain a portion of the asthma epidemic. The purpose of this review is to present the evidence for a role of vitamin D in asthma.

RECENT FINDINGS

Both animal models and studies in human fetal tissues show that vitamin D plays a role in fetal lung growth and maturation. Epidemiologic studies have also suggested that higher prenatal vitamin D intakes have a protective role against wheezing illnesses in young children. Vitamin D may protect against wheezing illnesses through its role in upregulating antimicrobial proteins or through its multiple immune effects. In addition, vitamin D may play a therapeutic role in steroid resistant asthmatics, and lower vitamin D levels have recently been associated with higher risks for asthma exacerbations.

SUMMARY

Improving vitamin D status holds promise in primary prevention of asthma, in decreasing exacerbations of disease, and in treating steroid resistance. However, the appropriate level of circulating vitamin D for optimal immune functioning remains unclear. Because vitamin D deficiency is prevalent even in sun-replete areas, clinical trials are needed to definitively answer questions about the role of vitamin D in asthma.

Is vitamin D deficiency to blame for the asthma epidemic?

In the 1960s, the prevalence of asthma and allergic diseases began to increase worldwide. Currently, the burden of the disease is more than 300 million people affected. We hypothesize that as populations grow more prosperous, more time is spent indoors, and there is less exposure to sunlight, leading to decreased cutaneous vitamin D production. Coupled with inadequate intake from foods and supplements, this then leads to vitamin D deficiency, particularly in pregnant women, resulting in more asthma and allergy in their offspring. Vitamin D has been linked to immune system and lung development in utero, and our epidemiologic studies show that higher vitamin D intake by pregnant mothers reduces asthma risk by as much as 40% in children 3 to 5 years old. Vitamin D deficiency has been associated with obesity, African American race (particularly in urban, inner-city settings), and recent immigrants to westernized countries, thus reflecting the epidemiologic patterns observed in the asthma epidemic. Providing adequate vitamin D supplementation in pregnancy may lead to significant decreases in asthma incidence in young children.

Maternal vitamin D intake during pregnancy and early childhood wheezing

BACKGROUND

Maternal intake of vitamin D in pregnancy is a potentially modifiable but understudied risk factor for the development of asthma in children.

OBJECTIVE

We investigated whether maternal vitamin D intake in pregnancy is associated with decreased risks of wheezing symptoms in young children.

DESIGN

Subjects were from a birth cohort recruited in utero with the primary objective of identifying associations between maternal diet during pregnancy and asthma and allergies in children. A random sample of 2000 healthy pregnant women was recruited while attending antenatal clinics at the Aberdeen Maternity Hospital, Scotland, at approximately 12 wk gestation. Maternal vitamin D intake was ascertained from a food-frequency questionnaire completed at 32 wk of gestation. The main outcome measures were wheezing symptoms, spirometry, bronchodilator response, atopic sensitization, and exhaled nitric oxide at 5 y.

RESULTS

Respiratory details through 5 y and maternal food-frequency-questionnaire data were available for 1212 children. In models adjusted for potential confounders, including the children's vitamin D intake, a comparison of the highest and lowest quintiles of maternal total vitamin D intake conferred lower risks for ever wheeze [odds ratio (OR): 0.48; 95% CI: 0.25, 0.91], wheeze in the previous year (OR: 0.35; 95% CI: 0.15, 0.83), and persistent wheeze (OR: 0.33; 95% CI: 0.11, 0.98) in 5-y-old children. In addition, lower maternal total vitamin D intakes in pregnancy were also associated with decreased bronchodilator response (P = 0.04). No associations were observed between maternal vitamin D intakes and spirometry or exhaled nitric oxide concentrations.

CONCLUSION

Increasing maternal vitamin D intakes during pregnancy may decrease the risk of wheeze symptoms in early childhood.

24,25-dihydroxy vitamin D3 treatment inhibits parathyroid-stimulated adenylate cyclase in iliac crest biopsies from uremic patients

Renal osteodystrophy with increased bone resorption is a major clinical problem in patients with chronic renal failure. Previous reports have shown that treatment with 24,25-dihydroxy vitamin D3 (24,25(OH)2D3) may result in decreased bone resorption. The present study addresses basic mechanisms for the action of 24,25(OH)2D3 in bone of patients with elevated serum parathyroid hormone (PTH) levels due to chronic renal disease. Twenty-four patients 56 +/- 17 years old (mean +/- SE) with chronic kidney disease in the predialytic state (serum creatinine > 150 mumol/l) and elevated serum midregion PTH > 1.2 micrograms/l were randomly assigned to oral treatment with either 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) (0.25-0.50 microgram/day), 24,25(OH)2D3 (daily dose of 15 micrograms), or a combination of the two vitamin D3 analogs. The control group received calcium carbonate (maximal dosage of 1 g x 3). Selected variables in serum and urine as well as hormone sensitive adenylate cyclase (AC) in iliac crest biopsies were assessed before treatment and during follow-up after two and six months. Serum levels of 1,25(OH)2D3 and 24,25(OH)2D3 were significantly (P < 0.05) increased after two and six months in the respective treatment groups. Net bone PTH-enhanced AC (PTH-AC) fell abruptly (P < 0.01) after two months of treatment and was nearly abolished (P < 0.01) after six months with 24,25(OH)2D3 given alone or in combination with 1,25(OH)2D3. An inverse relationship (r = -0.57, P < 0.05, n = 48) between net PTH-AC in bone and serum levels of 24,25(OH)2D3 was demonstrated. In all groups, serum total calcium (s-Ca) was maintained within normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone turnover in rats treated with 1,25-dihydroxyvitamin D3, 25-hydroxyvitamin D3 or 24,25-dihydroxyvitamin D3

Female rats were given 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 0.25 microgram per 100 g body weight (bw), 25-hydroxyvitamin D3 (25(OH)D3), 1.7 micrograms/100 g bw or 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) 1.7 micrograms/100 g bw, subcutaneously three times a week for 12 weeks. Traditional variables pertaining to calcium homeostasis and growth, i.e. blood and urine calcium (Ca) and phosphate (P), serum levels of vitamin D3 metabolites parathyroid hormone, (PTH), calcitonin (CT), prolactin (PRL) and growth hormone (GH) were measured every four weeks. This data pool was correlated with bone matrix turnover parameters, i.e. serum levels of alkaline phosphatase (ALP) and urinary hydroxyproline (u-HYP) excretion. After 12 weeks of treatment, 1,25(OH)2D3 significantly enhanced serum total and ionized Ca, urine Ca and urine P, and also diminished urine cAMP due to reduced renal function (creatinine clearance). However, 25(OH)D3 administration had no such impact. 24,25(OH)2D3 opposed the effect of 1,25(OH)2D3 after 12 weeks by significantly augmenting serum P and diminishing serum levels of total Ca and ionized Ca. Cross sectional group analyses showed that circulating levels of ALP were directly related with serum 1,25(OH)2D3 and inversely related to serum 24,25(OH)2D3 and CT. Total u-HYP and per cent non-dialysable HYP (ndHYP) were reciprocally and positively correlated with serum PRL, respectively. However, no such relations were observed with serum GH. It appears that rats with elevated circulating levels of 1,25(OH)2D3 exhibit increased bone resorption, while augmented 24,25(OH)2D3 is associated with the opposite. Apparently, high bone turnover (i.e. reduced total urinary HYP and enhanced ndHYP) is associated with high serum PRL.

Long-term administration of vitamin D3 metabolites alters PTH-responsive osteoblastic adenylate cyclase in rats

We have examined the effect of induced hyper D3 vitaminosis on bone-related variables in the rat with special reference to the parathyroid (PTH)-sensitive adenylate cyclase (AC) in rat calvariae. Subcutaneous injections three times a week of doses theoretically corresponding to about 10 times the average physiological serum levels of either 25 hydroxyvitamin D3 (25OHD3), 1,25 dihydroxyvitamin D3 (1,25(OH)2D3), or 24,25 dihydroxyvitamin D3 (24,25(OH)2D3) for 12 weeks gave the following results: At 12 weeks of treatment, 24,25(OH)2D3 levels in the groups receiving 25OHD3 or 24,25(OH)2D3 increased significantly, whereas 1,25(OH)2D3 levels remained unaffected. Correspondingly, PTH-sensitive AC activities in crude calvarial membrane fractions from 25OHD3- and 24,25(OH)2D3-treated animals were obliterated. This effect was apparent after 4 weeks of treatment. In the group receiving 25OHD3, both basal, plus Gpp(NH)p-, and forskolin-sensitive AC activities were significantly reduced after 4 weeks of treatment. Similar effects in crude kidney membrane fractions were, however, not observed. Liver membranes from 25OHD3- or 24,25(OH)2D3-treated animals showed insignificant changes in the isoprenalin-, PGE1-, Gpp(NH)p-, or forskolin-sensitive AC activities. Finally, the significance of reduced PTH-sensitive bone AC activity has been assessed. 25OHD3 treatment yielded normocalcemic and hypercalciuric rats, whereas 1,25(OH)2D3 enhanced both serum and urine Ca2+ levels. 24,25(OH)2D3-treated and control animals were undiscernible in this respect. However, the 24,25-(OH)2D3 treatment caused reductions in both serum alkaline phosphatase levels and urinary hydroxyproline/creatinine ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent developments in the roles of vitamins and minerals in reproduction

Vitamins and minerals affect reproductive function. Vitamin A deficiency has long been known to affect reproductive function in cattle. More recently, a role has been proposed for the vitamin A percursor, beta-carotene, in reproductive efficiency. Dietary supplementation with vitamin E and selenium may reduce the incidence of retained placenta, but these nutrients may also affect reproductive function in other ways. Calcium and phosphorus deficiencies affect reproduction in cattle, and vitamin D may directly affect reproductive function in addition to its role in calcium and phosphorus metabolism. Dietary manipulation of a number of other vitamins and minerals also influences reproductive function. However, the specific roles of nutrients in reproductive tissues are not well-defined in dairy cattle, and nutrient requirements for optimal reproductive efficiency in modern dairy cattle deserve careful reevaluation. This review provides a background of the effect of vitamins and minerals on reproduction and it attempts to provide a basis for further investigation of specific mechanisms by which reproductive function is affected. The interface between nutritional science and reproductive physiology provides considerable potential for optimizing reproductive efficiency in dairy cattle.