25-Hydroxyvitamin D in the range of 20 to 100 ng/mL and incidence of kidney stones.

OBJECTIVES: Increasing 25-hydroxyvitamin D serum levels can prevent a wide range of diseases. There is a concern about increasing kidney stone risk with vitamin D supplementation. We used GrassrootsHealth data to examine the relationship between vitamin D status and kidney stone incidence. METHODS: The study included 2012 participants followed prospectively for a median of 19 months. Thirteen individuals self-reported kidney stones during the study period. Multivariate logistic regression was applied to assess the association between vitamin D status and kidney stones. RESULTS: We found no statistically significant association between serum 25-hydroxyvitamin D and kidney stones (P = .42). Body mass index was significantly associated with kidney stone risk (odds ratio = 3.5; 95% confidence interval = 1.1, 11.3). CONCLUSIONS: We concluded that a serum 25-hydroxyvitamin D level of 20 to 100 nanograms per milliliter has no significant association with kidney stone incidence.

Meta-analysis of all-cause mortality according to serum 25-hydroxyvitamin D.

We examined the relationship between serum 25-hydroxyvitamin D (25[OH]D) and all-cause mortality. We searched biomedical databases for articles that assessed 2 or more categories of 25(OH)D from January 1, 1966, to January 15, 2013. We identified 32 studies and pooled the data. The hazard ratio for all-cause mortality comparing the lowest (0-9 nanograms per milliliter [ng/mL]) to the highest (> 30 ng/mL) category of 25(OH)D was 1.9 (95% confidence interval = 1.6, 2.2; P < .001). Serum 25(OH)D concentrations less than or equal to 30 ng/mL were associated with higher all-cause mortality than concentrations greater than 30 ng/mL (P < .01). Our findings agree with a National Academy of Sciences report, except the cutoff point for all-cause mortality reduction in this analysis was greater than 30 ng/mL rather than greater than 20 ng/mL.

Osteoporosis update: proceedings of the 2013 Santa Fe Bone Symposium.

The 2013 Santa Fe Bone Symposium included plenary sessions on new developments in the fields of osteoporosis and metabolic bone disease, oral presentations of abstracts, and faculty panel discussions of common clinical conundrums: scenarios of perplexing circumstances where treatment decisions are not clearly defined by current medical evidence and clinical practice guidelines. Controversial issues in the care of osteoporosis were reviewed and discussed by faculty and participants. This is a review of the proceedings of the Santa Fe Bone Symposium, constituting in its entirety an update of advances in the understanding of selected bone disease topics of interest and the implications for managing patients in clinical practice. Topics included the associations of diabetes and obesity with skeletal fragility, the complexities and pitfalls in assessing the benefits and potential adverse effects of nutrients for treatment of osteoporosis, uses of dual-energy X-ray absorptiometry beyond measurement of bone mineral density, challenges in the care of osteoporosis in the very elderly, new findings on the role of osteocytes in regulating bone remodeling, and current concepts on the use of bone turnover markers in managing patients with chronic kidney disease who are at high risk for fracture.

All-source basal vitamin D inputs are greater than previously thought and cutaneous inputs are smaller.

The magnitude of vitamin D inputs in individuals not taking supplements is unknown; however, there is a great deal of information on quantitative response to varying supplement doses. We reanalyzed individual 25-hydroxyvitamin D [25(OH)D] concentration data from 8 studies involving cholecalciferol supplementation (total sample size = 3000). We extrapolated individual study dose-response curves to zero concentration values for serum 25(OH)D by using both linear and curvilinear approaches and measured seasonal oscillation in the serum 25(OH)D concentration. The total basal input (food plus solar) was calculated to range from a low of 778 iu/d in patients with end-stage renal disease to a high of 2667 iu/d in healthy Caucasian adults. Consistent with expectations, obese individuals had lower baseline, unsupplemented 25(OH)D concentrations and a smaller response to supplements. Similarly, African Americans had both lower baseline concentrations and lower calculated basal, all-source inputs. Seasonal oscillation in 4 studies ranged from 5.20 to 11.4 nmol/L, reflecting a mean cutaneous synthesis of cholecalciferol ranging from 209 to 651 iu/d at the summer peak. We conclude that: 1) all-source, basal vitamin D inputs are approximately an order of magnitude higher than can be explained by traditional food sources; 2) cutaneous, solar input in these cohorts accounts for only 10-25% of unsupplemented input at the summer peak; and 3) the remainder must come from undocumented food sources, possibly in part as preformed 25(OH)D.

What is vitamin D insufficiency? And does it matter?

The term nutrient "insufficiency," as commonly used, refers to a nutritional status intermediate between classical, severe deficiency, and full normal. As both "deficiency" and "insufficiency" are causes of dysfunction and disease, there is no biological basis for a distinction between them. What is important to note is that, in the case of vitamin D, the preponderance of the evidence indicates that there is real, preventable disease in the range of vitamin D status values now labeled "insufficient."

Effect of a combination of genistein, polyunsaturated fatty acids and vitamins D3 and K1 on bone mineral density in postmenopausal women: a randomized, placebo-controlled, double-blind pilot study.

PURPOSE: Many postmenopausal women desire non-pharmaceutical alternatives to hormone therapy for protection against osteoporosis. Soybean isoflavones, especially genistein, are being studied for this purpose. This study examined the effects of synthetic genistein in combination with other potential bone-protective dietary molecules on bone mineral density (BMD) in early postmenopausal women. METHODS: In this 6-month double-blind pilot study, 70 subjects were randomized to receive daily either calcium only or the geniVida™ bone blend (GBB), which consisted of genistein (30 mg/days), vitamin D3 (800 IU/days), vitamin K1 (150 µg/days) and polyunsaturated fatty acids (1 g polyunsaturated fatty acids as ethyl ester: eicosapentaenoic acid/docosahexaenoic acid ratio = ~2/1). Markers of bone resorption and formation and BMD at the femoral neck, lumbar spine, Ward's triangle, trochanter and intertrochanter, total hip and whole body were assessed. RESULTS: Subjects supplemented with the GBB (n = 30) maintained femoral neck BMD, whereas in the placebo group (n = 28), BMD significantly decreased (p = 0.007). There was also a significant difference (p < 0.05) in BMD between the groups at Ward's triangle in favor of the GBB group. Bone-specific alkaline phosphatase and N-telopeptide significantly increased in the GBB group in comparison with those in baseline and in the placebo group. The GBB was well tolerated, and there were no significant differences in adverse events between groups. CONCLUSIONS: The GBB may help to prevent osteoporosis and reduce fracture risk, at least at the hip, in postmenopausal women. Larger and longer-term clinical trials are warranted.

Assessing vitamin D status.

PURPOSE OF REVIEW: To characterize methods evaluating and to summarize studies linking various serum 25-hydroxyvitamin D [25(OH)D] concentrations with health status. RECENT FINDINGS: Elucidation of the cell-biologic mechanism of vitamin D action, and numerous clinical trials and observational studies relating vitamin D status to health and disease. CONCLUSION: The distinction between deficiency and insufficiency is not useful or necessary. Serum 25(OH)D values below 120  nmol/l (48  ng/ml) are associated with preventable disease and are therefore indicative of deficiency. The upper limit of the normal range can be set at 225  nmol/l (90  ng/ml), although toxicity is rare below 500  nmol/l (200  ng/ml).

Bone mineral density discordance and exploration of one of its causes.

Discordances between hip and spine areal density T-score values are common and incompletely understood. In a cohort of 1157 postmenopausal women, discordances of greater than 10% occurred in 91%, with spine bone mineral density (BMD) T-scores significantly less negative than femoral neck (FN) T-scores (p<0.001). However, when T-scores based on bone mineral content (BMC) rather than BMD were used, the mean discordance was not significantly different from 0. This was largely because BMC at the FN had seemingly declined with age less rapidly than had BMD at that site. This can be explained by age-related areal expansion at the hip, which would be missed in the reported BMD output. One consequence is that if BMC-based T-scores are used to classify patients, substantially fewer individuals would have been judged osteoporotic in this cohort (two-thirds fewer for spine and three-fourths fewer for hip).

Vitamin D: the iceberg nutrient.

The understanding of vitamin D's role in human health has recently expanded. It is now recognized as more than a hormone activated in the kidney only for calcium homeostasis. It is metabolized and used by virtually every cell in the body. Patients with chronic kidney disease have a deficit in their kidney production of 1,25(OH)(2)D and have classically been treated with calcitriol or its active analogues. Despite often having lower systemic levels of 1,25(OH)(2)D, patients with chronic kidney disease retain the capability of extra renal production of 1,25(OH)(2)D. This has far reaching implications for their health. This review examines clinical trials and observations in 3 areas that impact chronic kidney disease patients. Cancer, cardiovascular disease and infections are responsible for much of the morbidity and mortality in this patient population. We will discuss vitamin D's role in these disease states with a focus on the chronic kidney disease patient.

Differential effects of paricalcitol and calcitriol on intestinal calcium absorption in hemodialysis patients.

BACKGROUND/AIMS: Increased parathyroid activity associated with chronic kidney disease is often managed with calcitriol, which can elevate serum calcium (Ca) by increasing bone resorption and intestinal absorption, whereas paricalcitol promotes less bone resorption. This study compared intestinal Ca absorption in hemodialysis patients treated with calcitriol versus paricalcitol (dose ratio 1:3). METHODS: Patients (n = 22) aged > or =20 years, on maintenance hemodialysis for > or =2 months with intact parathyroid hormone (iPTH) levels of >200 pg/ml were enrolled in a single-center, double-blind, active-controlled, randomized, crossover trial. Mean fractional intestinal Ca absorption (+/-SE) was measured by the single-tracer method ((42)Ca) and evaluated with an analysis of variance crossover model. RESULTS: Mean fractional intestinal Ca absorption was significantly lower after paricalcitol (0.135 +/- 0.006) versus calcitriol treatment (0.158 +/- 0.006, p = 0.022), a 0.023 difference in absolute Ca absorption fraction. Overall Ca absorption was low in the study population, indicating that regulation of Ca absorption may be dysfunctional. There were no significant differences in serum PTH, Ca, phosphorus (P), or Ca x P. CONCLUSION: Overall, paricalcitol-treated patients absorbed approximately 14% less Ca compared with calcitriol-treated patients with similar effects on PTH. In hemodialysis patients, paricalcitol may provide a benefit by lowering the Ca available for removal by dialysis and/or for deposit in bone or soft tissues.

Dairy products and prostate cancer risk.

Increased calcium intake from dairy products has been suggested as a risk factor for prostate cancer. We propose that the high dietary phosphate of dairy products may more readily explain this risk rather than the increased calcium. Several epidemiologic correlations have indicated an increased risk of prostate cancer with long-term, high intake of dairy products in male U.S. physicians and males in Sweden. This relation has been mechanistically associated with the higher dietary intake of calcium in dairy products. We propose, however, that the high dietary phosphate of dairy products affects much larger fluctuation in serum phosphate and may be a more likely source of prostate cancer risk from high dietary intake of dairy products.

It is time for a positive approach to dietary guidance using nutrient density as a basic principle.

The consumption of nutrient-dense foods and beverages, which would ultimately be identified by a scientifically validated nutrient density profiling system, should be instituted as a nutrition platform in the Dietary Guidelines as a part of a larger educational effort to help people choose more nutrient-dense foods and as the guiding principle for consumers to plan healthful diets. By consciously choosing more nutrient-dense foods and beverages, Americans will be in a better position to meet their nutrient requirements without overconsuming energy. An objective, science-based, and validated nutrient density profiling system is needed to characterize foods based on their nutrient composition and this concept should be integrated into the Dietary Guidelines. This article sets forth guiding principles for the development and implementation of a nutrient density profiling system based on the current knowledge of diet and health and recommends that the development of a nutrient density profiling system include testing for effectiveness against accepted measures of diet quality, such as the Healthy Eating Index, and measurable public health markers, such as blood lipids and blood pressure.

Dairy and bone health.

Bone health is the resultant of bone mass, bone architecture, and body mechanics. Nutrition supports all three components, with the principal nutrients concerned being calcium, protein, and vitamin D. Potassium, magnesium, zinc, and several vitamins are also involved to varying extents. Given modern food sources, it is difficult to devise a diet that is "bone healthy" without including three servings of dairy per day, not just because of dairy calcium, but dairy protein and potassium as well.

Vitamin D3 distribution and status in the body.

OBJECTIVE: To estimate the amount, type, and tissue distribution of vitamin D in the adult body under typical inputs. METHODS: Review and reanalysis of published measurements and analysis of tissue samples from growing pigs raised in confinement on diets providing about 2000 IU vitamin D/day. Cholecalciferol and 25-hydroxyvitamin D [25(OH)D] concentration measured by HPLC. RESULTS: Mean serum 25(OH)D in all studies combined was 45 nmol/L. At the level of vitamin D repletion represented by this concentration, total body vitamin D would be 14,665 IU for a 70 kg adult woman. 65% of this total was present as native cholecalciferol and 35% as 25(OH)D. Nearly three-quarters of the cholecalciferol was in fat, while 25(OH)D was more evenly distributed throughout the body (20% in muscle, 30% in serum, 35% in fat, and 15% in all other tissues). At the daily vitamin D consumption rates in these animals total body stores provided only a approximately 7-day reserve. CONCLUSIONS: At total intakes on the order of 2000 IU/day, an adult has very little vitamin D reserve, despite intakes 10x the current recommendations. Those recommended inputs need to be increased by at least an order of magnitude. Food tables that fail to take into account 25(OH)D content of various meat products lead to underestimation of dietary vitamin D intake.

Do melanoidins induced by topical 9% dihydroxyacetone sunless tanning spray inhibit vitamin d production? A pilot study.

We report here preliminary pilot study data of the effect of sunless tanning spray with 9% [Correction added after online publication (August 24th, 2009): The concentration of Dihydroxyacetone used in the study was 9% and not 3% as previously stated] dihydroxyacetone (DHA) on 25-hydroxyvitamin D [25(OH)D] serum levels in subjects exposed to controlled amounts of UV-B radiation during April/May in Omaha, NE, 41 degrees N latitude. We found that DHA-induced melanoidins in skin act as a topical sunscreen attenuating the formation of 25(OH)D.