Reinhold Vieth

University of Toronto | U of T · Department of Laboratory Medicine and Pathobiology

Context and purpose: Individual participant data-level meta-regression (IPD) analysis is superior to meta-regression based on aggregate data in determining Dietary Reference Values (DRV) for vitamin D. Using data from randomized controlled trials (RCTs) with vitamin D3-fortified foods, we undertook an IPD analysis of the response of winter serum 2...

This is an update of the previous 2018 systematic review and meta-analysis of vitamin and mineral supplementation on cardiovascular disease outcomes and all-cause mortality. New randomized controlled trials and meta-analyses were identified by searching the Cochrane library, Medline, and Embase, and data were analyzed using random effects models an...

The biology of every species has been optimized for life in the environment in which that species evolved. Humans originated in the tropics, and while some natural selection took place in response to behaviors and environments that decreased exposure to ultraviolet light, there has never been a species-wide biological accommodation. Paleolithic nut...

The specific compound that is meant for use in the context of vitamin D supplementation is often ambiguous. The term “supplementation” has been used in the context of cholecalciferol, ergocalciferol, calcidiol, and calcitriol. In nature, by far the major form of vitamin D that nurtures the body is cholecalciferol. In contrast, ergocalciferol is pri...

The original version of this article, published on 06 November 2019 unfortunately contained a mistake.

The vitamin D paradox relates to the lower risk of osteoporosis in people of sub-Saharan African ancestry (Blacks) compared with people of European ancestry (Whites). The paradox implies that for bone health, Blacks require less vitamin D and calcium than Whites do. Why should populations that migrated northward out of Africa have ended up needing...

Purpose Epidemiologic and preclinical data suggest a potential role for vitamin D in breast cancer treatment and prevention. However, results of prospective randomized trials are inconsistent. The objective of this study was to assess the effects of high-dose cholecalciferol (vitamin D3) on breast tumour proliferation and apoptosis. Methods We con...

Objective In the phase II, randomized, double-blind, placebo-controlled Supplementation of Vigantol Oil versus Placebo Add-on in Patients with Relapsing-Remitting Multiple Sclerosis (RRMS) Receiving Rebif Treatment (SOLAR) study (NCT01285401), we assessed the efficacy and safety of add-on vitamin D3 in patients with RRMS. Methods Eligible patients...

Background Vitamin D nutrition research requires accurate measures of circulating 25-hydroxyvitamin D. Our objectives were to test whether a diurnal fluctuation in blood-spot concentrations of 25-hydroxyvitamin D can be demonstrated statistically in a single individual, and whether such fluctuation is affected by the pre-dose versus post-dose timin...

Vitamin D deficiency can lead to musculoskeletal diseases such as rickets and osteomalacia, but vitamin D supplementation may also prevent extraskeletal diseases such as respiratory tract infections, asthma exacerbations, pregnancy complications and premature deaths. Vitamin D has a unique metabolism as it is mainly obtained through synthesis in th...

The authors identified individual randomized controlled trials from previous meta-analyses and additional searches, and then performed meta-analyses on cardiovascular disease outcomes and all-cause mortality. The authors assessed publications from 2012, both before and including the U.S. Preventive Service Task Force review. Their systematic review...

There is still controversy about the amount of vitamin D adults need for musculoskeletal health. The Endocrine Society, which made its recommendations for the treatment and prevention of vitamin D deficiency, concluded that to guarantee bone health without any evidence for vitamin D deficiency osteomalacia, a blood level of 25(OH)D of at least 75....

Vitamin D3 is produced in the skin in response to UVB irradiation, from either sun exposure or UVB sunbeds. The objective of the current study was to characterize serum 25(OH)D response to regular sunbed use from several lamp outputs following their respective time exposure recommendations. There were three groups that tanned over 12 weeks during t...

Background: This double-blind, placebo-controlled parallel-group trial assessed whether oral supplementation with 1,000, 2,000 or 3,000 IU/day vitamin D3 over one year reduces percent mammographic breast density in premenopausal women. Methods: The trial was conducted between October 2012 and June 2015, among premenopausal female volunteers from...

Few data exist on bone turnover in South Asian women and it is not well elucidated as to whether Western dwelling South Asian women have different bone resorption levels to that of women from European ethnic backgrounds. This study assessed bone resorption levels in UK dwelling South Asian and Caucasian women as well as evaluating whether seasonal...

Vitamin D deficiency increases the risk of lethal prostate adenocarcinomas (PCa) and the majority of older men are deficient. Although PCa arises from the epithelium, the surrounding stroma has hormonal regulatory control over the epithelium and contributes to carcinogenesis. Herein, we describe regulation of microRNAs (miRs) by the active hormone...

Vitamin D deficiency causes rickets in children and osteomalacia in adults, both of which are accompanied by muscle weakness. Deficiency is measureable by a blood test of the vitamin D metabolite, 25-hydroxyvitamin D [25(OH)D]. Disagreements about the need for vitamin D are based on differing opinions about desirable health-related thresholds for s...

Aims: Low serum 25-hydroxyvitamin-D [25(OH)D] concentrations are associated with insulin resistance, β-cell dysfunction and type 2 diabetes. We conducted a 24-week double-blind, randomized, placebo-controlled trial to examine the effect of 28 000 IU of vitamin D3 once weekly on plasma glucose after a 2h-75g oral glucose tolerance test (2hrPC gluco...

To assess the bioavailability and safety of vitamin D3 from fortified mozzarella cheese baked on pizza. In a randomized, double-blind trial, 96 apparently healthy, ethnically diverse adults were randomized to consume 200 IU or 28 000 IU vitamin D3 fortified mozzarella cheese with pizza once weekly for a total of 8 weeks. Blood and urine samples wer...

Vitamin D has immunomodulatory effects that might aid clearance of mycobacterial infection. We aimed to assess whether vitamin D supplementation would reduce time to sputum culture conversion in patients with active tuberculosis. We did this randomised, double-blind, placebo-controlled, superiority trial at 13 sites in India. Treatment-naive patien...

American Society for Nutrition annual meeting at Experimental Biology, .

The NCIC CTG Symptom Control.20 randomized trial (SC.20) confirmed the effectiveness of re-irradiation to painful bone metastases. This companion study correlates urinary markers of osteoclast activity with response to re-irradiation, survival and skeletal related events (SREs). Pain response was assessed using the International Consensus Endpoints...

Objective: It has been suggested that vitamin D may play a role in the pathogenesis of several endocrine diseases, such as hyperparathyroidism, type 1 diabetes (T1DM), type 2 diabetes (T2DM), autoimmune thyroid diseases, Addison's disease and polycystic ovary syndrome (PCOS). In this review, we debate the role of vitamin D in the pathogenesis of e...

We conducted a single-arm clinical trial in institutionalized seniors, on the effects of high-dose vitamin D3-fortified bread daily intake (clinicaltrials.gov registration NCT00789503). At 1 and 3 years after the dietary fortification was stopped, serum 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and bone mineral density were measured...

This analysis assessed whether seasonal change in 25-hydroxyvitamin D concentration was associated with bone resorption, as evidenced by serum parathyroid hormone and C-terminal telopeptide concentrations. The main finding was that increased seasonal fluctuation in 25-hydroxyvitamin D was associated with increased levels of parathyroid hormone and...

Animal models suggest a key role for dihydroxylated vitamin D metabolites in fracture healing, as evidenced by increases in serum concentration of 24R,25-dihydroxyvitamin D (24R,25[OH]2D) after long bone fracture. Human studies investigating the kinetics of serum concentrations of 24R,25[OH]2D, 1,25-dihydroxyvitamin D (1,25[OH]2D) and their parent...

Key points: • Vitamin D has become recognized by policy makers as a nutrient that needs to be provided to institutionalized seniors, because it prevents osteoporotic fractures. • Since older adults receive many medications, it may be preferable to fortify their food with vitamin D, rather than provide it as yet another pill. • In a clinical trial i...

MiR-100 and miR-125b are lost in many cancers and have potential function as tumor suppressors. Using both primary prostatic epithelial cultures and laser-capture-microdissected prostate epithelium from 45 patients enrolled in a vitamin D3 randomized trial, we identified miR-100 and -125b as targets of 1,25-dihydroxyvitamin D3 (1,25D). In patients,...

The vitamin D receptor (VDR) maintains a balance of plasma calcium and 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], its natural active ligand, by directly regulating the calcium ion channel (TRPV6) and degradation enzyme (CYP24A1), and indirectly regulating the parathyroid hormone (PTH) for feedback regulation of the synthetic enzyme, CYP27B1. Studies...

Context: Vitamin D3 might benefit prostate cancer (PCa) patients because prostate cells can locally synthesize the active hormone calcitriol. Objective: Our objective was to determine the effects of oral vitamin D3 on vitamin D metabolites and PCa proliferative activity in prostate tissue. Design and setting: We conducted a double-blind random...

ContextVitamin D may play a role in the aetiology of the metabolic syndrome (MetS), yet the majority of previous studies have been cross-sectional, and the limited number of prospective studies has yielded inconsistent results. Objective To examine the prospective association of vitamin D [25-hydroxyvitamin D, 25(OH)D] with MetS in a multi-ethnic c...

Vitamin D has become recognized by policy makers as a nutrient that needs to be provided to institutionalized seniors, because it prevents osteoporotic fractures. • Since older adults receive many medications, it may be preferable to fortify their food with vitamin D, rather than provide it as yet another pill. • In a clinical trial in Eastern Euro...

Purpose: Androgen deprivation therapy (ADT) has been used as an adjuvant treatment to radiation therapy (RT) for the management of locally advanced prostate carcinoma. Long-term ADT decreases bone mineral density (BMD) and increases the risk of osteoporosis. The objective of this clinical trial was to evaluate the efficacy of risedronate for the p...

Background Exposure to solar ultraviolet-B (UV-B) radiation is a major source of vitamin D3. Chemistry climate models project decreases in ground-level solar erythemal UV over the current century. It is unclear what impact this will have on vitamin D status at the population level. The purpose of this study was to measure the association between gr...

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Background: Preclinical data suggest that vitamin D plays a favourable role in prostate cancer prevention and prognosis, but its putative anticancer effects have not been validated in clinical prostate tissue samples. Here, we report the results from a randomized clinica...

Currently, there is a lack of clarity in the literature as to whether there is a definitive difference between the effects of vitamins D2 and D3 in the raising of serum 25-hydroxyvitamin D [25(OH)D]. The objective of this article was to report a systematic review and meta-analysis of randomized controlled trials (RCTs) that have directly compared t...

Vitamin D status is of interest to physicians caring for patients in poor general health. The tool for assessing vitamin D status is the serum 25-hydroxyvitamin D (25(OH)D) concentration. Based on clinical trials and epidemiology the low end of the desirable concentration of this analyte generally ranges from 50 nmol/L to 75 nmol/L. Based on clinic...

A novel method to measure 1,25-dihydroxyvitamin D (1,25(OH)(2)D) in human tissue was developed and validated. The objectives of this study were to determine whether 1,25(OH)(2)D is present in human colon tissue and to characterize the relationship between human colon tissue and serum 1,25(OH)(2)D concentrations. Normal colon tissue specimens and ma...

There is emerging evidence of a relationship between vitamin D insufficiency and glucose intolerance. The aim of this study was to determine whether low serum 25-hydroxyvitamin D in early pregnancy is associated with an increased risk of gestational diabetes mellitus. This nested case-control study examined the association between serum 25-hydroxyv...

To examine the prospective associations of baseline vitamin D [25-hydroxyvitamin D; 25(OH)D] with insulin resistance (IR), β-cell function, and glucose homeostasis in subjects at risk for type 2 diabetes. We followed 489 subjects, aged 50 ± 10 years, for 3 years. At baseline and follow-up, 75-g oral glucose tolerance tests (OGTTs) were administered...

The Institutes of Medicine (IOM) recently revised the recommended dietary allowances (RDA) for vitamin D, to maintain serum 25-hydroxyvitamin D (25(OH)D) at or above 50 nmol/L, to sustain bone density, calcium absorption, and to minimize risk of osteomalacia and rickets. However there are compelling reasons why 25(OH)D should preferably exceed 75 n...

To characterize the effect of vitamin D(3) intake on urinary calcium:creatinine ratios across predefined ranges of serum 25(OH)D. Patients with multiple sclerosis (n=25) received escalating doses of vitamin D(3) (4000-40,000IU/d) with calcium (1200mg/d). Urinary calcium:creatinine was driven by increased 25(OH)D when concentrations were <75nmol/L (...

The active metabolite of vitamin D, 1,25-dihydroxyvitamin D [1,25(OH)(2)D], is a potent modulator of immune cells in vitro. Our objective was to determine whether the sun-dependent nutrient, cholecalciferol, can alter disease-associated cellular immune abnormalities in patients with multiple sclerosis (MS). This was an open-label, 12-month, randomi...

The fetal-origin hypothesis has reshaped the way of scientific thinking by identifying that the in utero and postnatal metabolic environment can be memorized by the developing organism through fetal and neonatal imprinting. In light of this hypothesis, prenatal and postnatal events can be thought of as the foundation for structural and functional d...

Recent studies have demonstrated the immunomodulatory properties of vitamin D, and vitamin D deficiency may be a risk factor for the development of MS. The risk of developing MS has, in fact, been associated with rising latitudes, past exposure to sun and serum vitamin D status. Serum 25-hydroxyvitamin D [25(OH)D] levels have also been associated w...

24,25-Dihydroxyvitamin D (24,25VD) is a major catabolite of 25-hydroxyvitamin D (25VD) metabolism, and may be physiologically active. Our objectives were to: (1) characterize the response of serum 24,25VD(3) to vitamin D(3) (VD(3)) supplementation; (2) test the hypothesis that a higher 24,25VD(3) to 25VD(3) ratio (24,25:25VD(3)) predicts 25VD(3) re...

HLA-DRB1*15 genotype, previous infection with Epstein-Barr virus, and vitamin D insufficiency are susceptibility factors for multiple sclerosis, but whether they act synergistically to increase risk is unknown. We aimed to assess the contributions of these risk factors and the effect of established precursors of multiple sclerosis, such as brain le...

In the July 12, 2010, issue of the Archives,1 Grey and Bolland1(p1099) opine “it seems intuitively unlikely that a single hormone could play a substantial role in . . . the diverse range of diseases” linked to vitamin D. Forgetting for a moment the multiform effects of hormones such as cortisol and thyroxine, we note that vitamin D (as calcitriol)...

The Rank Forum on Vitamin D was held on 2nd and 3rd July 2009 at the University of Surrey, Guildford, UK. The workshop consisted of a series of scene-setting presentations to address the current issues and challenges concerning vitamin D and health, and included an open discussion focusing on the identification of the concentrations of serum 25-hyd...

Pharmacology imposes a discipline about the administration of vitamin D that has been too often ignored, with the consequence of sometimes causing patients more harm than good. While the distinction between a drug and a dietary supplement is largely semantic, the pharmacological perspective is important, because it imposes a discipline that has bee...

Vitamin D deficiency is a highly prevalent condition that is present in 40% to 80% of pregnant women. There is emerging evidence that vitamin D deficiency may be a risk modifying factor for many chronic diseases, including osteomalacia, rickets, multiple sclerosis, schizophrenia, heart disease, type 1 diabetes, and cancer. Heightened susceptibility...

Recent research suggests that 1,25-dihydroxyvitamin D [1,25(OH)(2)D], a steroid hormone that regulates calcium homeostasis, may also play a role in the development and progression of cancer, multiple sclerosis, cardiovascular, and other diseases. Decreased serum 1,25(OH)(2)D concentrations are often observed in overweight and obese patients. Howeve...

Emerging evidence suggests that 25-hydroxy vitamin D [25(OH)D] and PTH may play a role in the etiology of the metabolic syndrome (MetS). However, evidence to date is limited and inconsistent, and few studies have examined associations with nontraditional MetS components. The objective of the study was to examine the association of vitamin D and PTH...

Previous research indicates that circulating vitamin D levels are low in many otherwise healthy adults and that there is considerable seasonal variation in 25-hydroxyvitamin D [25(OH)D] concentrations at high latitudes. We examined seasonal variation in 25(OH)D levels in a sample of young adults of diverse ancestry living in the Greater Toronto Are...

An inadequate vitamin D supply per se does not fully explain the role of vitamin D in the prevention of cancer. The paradigm for the vitamin D system differs from the rest of endocrinology because the enzymes that metabolize 25-hydroxyvitamin D [25(OH)D] behave according to first-order reaction kinetics in vivo. Perpetually fluctuating 25(OH)D in t...

The serum 25-hydroxyvitamin D [25(OH)D] level measures vitamin D status. Clinical trials show that treatment with vitamin D, 800 IU/day, along with calcium, 1200 mg/day, lowers risk of fractures in older adults, as well as falls. Since the trials showed that a mean serum 25(OH)D of approximately 75 nmol/L (30 ng/mL), from the combination of diet, s...

During the last decade, approaches to evidence-based medicine, with its heavy reliance on the randomized clinical trial (RCT), have been adapted to nutrition science and policy. However, there are distinct differences between the evidence that can be obtained for the testing of drugs using RCTs and those needed for the development of nutrient requi...

Low vitamin D status has been associated with multiple sclerosis (MS) prevalence and risk, but the therapeutic potential of vitamin D in established MS has not been explored. Our aim was to assess the tolerability of high-dose oral vitamin D and its impact on biochemical, immunologic, and clinical outcomes in patients with MS prospectively. An open...

Some evidence suggests that vitamin D may reduce breast cancer risk. Despite the biological interaction between vitamin D and calcium, few studies have evaluated their joint effects on breast cancer risk. The objective was to evaluate the associations and potential interaction between vitamin D and calcium (from food and supplements) and breast can...

Twenty-two patients with steroid-induced osteoporosis were studied retrospectively to assess the effects on bone mass of fluoride therapy over 4 years. Thirteen of 19 patients with miscellaneous disorders and 2 with Cushing's syndrome received 1 g calcium/day, 50,000 IU vitamin D (D) weekly, and 40-60 mg/day sodium fluoride (F). Six patients with m...

The possible effects of fluoride in inducing fractures were studied in 61 patients treated with sodium fluoride (NaF), 40-60 mg daily in combination with calcium and vitamin D. Nine patients developed the fluoride-(F) related lower extremity pain syndrome. Four other patients had stress fractures associated with trauma. Seven of the 61 patients had...

To examine cross-sectional associations of serum vitamin D [25-hydroxyvitamin D, 25(OH)D] concentration with insulin resistance (IR) and beta-cell dysfunction in 712 subjects at risk for type 2 diabetes. Serum 25(OH)D was determined using a chemiluminescence immunoassay. Insulin sensitivity/resistance were measured using the Matsuda insulin sensiti...