Molecular Mechanisms for Regulation of Intestinal Calcium and Phosphate Absorption by Vitamin D

Fleet, James C.; Schoch, Ryan D.

doi:10.1016/b978-0-12-381978-9.10019-8

Cited by 14 publications

(13 citation statements)

References 123 publications

(149 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Each segment of the mammalian small intestine is capable of transporting calcium. Calcium absorption has been reported to be greatest in the ileum (65%), followed by jejunum (17%) and then duodenum (8%) [8][9][10][11]. There is also evidence for a colonic component of intestinal calcium absorption [12].…”

Section: Overall Process Of Intestinal Calcium Absorptionmentioning

confidence: 95%

Mechanism of action of 1,25-dihydroxyvitamin D3 on intestinal calcium absorption

Christakos

2011

Rev Endocr Metab Disord

View full text Add to dashboard Cite

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) is the major controlling hormone of intestinal calcium absorption. As the body's demand for calcium increases from a diet deficient in calcium, from growth, pregnancy or lactation, the synthesis of 1,25(OH)(2)D(3) is increased resulting in the stimulation of intestinal calcium absorption. However a complete description of the molecular mechanisms involved in the 1,25(OH)(2)D(3) regulated calcium absorptive process remains incomplete. Intestinal calcium absorption occurs by both an active saturable transcellular pathway and a passive nonsaturable paracellular pathway. Each step in the process of transcellular calcium transport (apical entry of calcium, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the plasma membrane pump) has been reported to involve a vitamin D dependent component. This article will review recent studies, including those using knockout mice, that have suggested that 1,25(OH)(2)D(3) mediated calcium absorption is more complex than the traditional three step model of transcellular calcium transport. Current concepts are reviewed and questions that remain are addressed. Evidence for a role of 1,25(OH)(2)D(3) in the regulation of the paracellular pathway is also discussed.

show abstract

Section: Overall Process Of Intestinal Calcium Absorptionmentioning

confidence: 95%

Mechanism of action of 1,25-dihydroxyvitamin D3 on intestinal calcium absorption

Christakos

2011

Rev Endocr Metab Disord

View full text Add to dashboard Cite

show abstract

“…Intestinal calcium transport occurs through an active, energy-dependent, saturable (presumably transcellular) pathway as well as through a passive, diffusional, nonsaturable (presumably paracellular) pathway [27]. The active, transcellular pathway predominates in the setting of low calcium intake, while passive, paracellular transport increases in importance in the setting of high calcium intake.…”

Section: Intestinal Calcium Transport: Normal Physiologymentioning

confidence: 99%

Vitamin D and intestinal calcium transport after bariatric surgery

Schafer

2017

The Journal of Steroid Biochemistry and Molecular Biology

View full text Add to dashboard Cite

Bariatric surgery is a highly effective treatment for obesity, but it may have detrimental effects on the skeleton. Skeletal effects are multifactorial but mediated in part by nutrient malabsorption. While there is increasing interest in non-nutritional mechanisms such as changes in fat-derived and gut-derived hormones, nutritional factors are modifiable and thus represent potential opportunities to prevent and treat skeletal complications. This review begins with a discussion of normal intestinal calcium transport, including recent advances in our understanding of its regulation by vitamin D, and areas of continued uncertainty. Human and animal studies of vitamin D and intestinal calcium transport after bariatric surgery are then summarized. In humans, even with optimized 25-hydroxyvitamin D levels and recommended calcium intake, fractional calcium absorption decreased dramatically after Roux-en-Y gastric bypass (RYGB). In rats, intestinal calcium absorption was lower after RYGB than after sham surgery, despite elevated 1,25-dihyroxyvitamin D levels and intestinal gene expression evidence of vitamin D responsiveness. Such studies have the potential to shed new light on the physiology of vitamin D and intestinal calcium transport. Moreover, understanding the effects of bariatric surgery on these processes may improve the clinical care of bariatric surgery patients.

show abstract

“…In humans, the presence of CYP27B1 in the duodenum (3,37) and colon (38) has already been demonstrated. It is likely that the 1␣-hydroxylase is present in many cells of the gastrointestinal tract, and conversion of 25(OH)D to 1,25(OH) 2 D takes place within the target cell for autocrine use (8). Jones (24) recently brought forward another hypothesis on the possible beneficial effect of 25(OH)D supplementation: native vitamin D may be able to protect calcitriol from degradation by CYP24A1, thus generating higher intracellular calcitriol levels in 25(OH)D uptaking cells.…”

Section: Discussionmentioning

confidence: 99%

“…Human intestinal calcium absorption is moderately efficient and declines with aging (2)(3)(4). It is generally accepted that the principal regulator of intestinal calcium absorption is circulating 1,25-dihydroxyvitamin D [1,25(OH) 2 D; calcitriol], the active metabolite of 25-hydroxyvitamin D [25(OH)D] (5)(6)(7)(8), which is produced through renal hydroxylation of 25(OH)D by the enzyme 1␣-hydroxylase (CYP27B1) (7,9). To date, the role of 25(OH)D in calcium absorption remains controversial (8, 10 -15).…”

mentioning

confidence: 99%

A Challenging Case of Hypocalcemia Supporting the Concept That 25-Hydroxyvitamin D Status Is Important for Intestinal Calcium Absorption

Amrein

Worm

Schilcher

et al. 2012

The Journal of Clinical Endocrinology &Amp; Metabolism

View full text Add to dashboard Cite

This case is clinically relevant because it demonstrates that efficient calcium absorption is markedly reduced in profound vitamin D deficiency, even with normal active vitamin D levels. An important consequence is to stay aware of vitamin D deficiency in patients with compromised kidney function irrespective of regular calcitriol replacement. Second, when both parenteral and oral vitamin D administration are contraindicated, ineffective, or unavailable, UVB phototherapy is an effective option to treat vitamin D deficiency. Third, this case underlines the importance of obtaining regular 25-hydroxyvitamin D levels in complex clinical cases when prediction of individual response is unreliable.

show abstract

Molecular Mechanisms for Regulation of Intestinal Calcium and Phosphate Absorption by Vitamin D

Cited by 14 publications

References 123 publications

Mechanism of action of 1,25-dihydroxyvitamin D3 on intestinal calcium absorption

Mechanism of action of 1,25-dihydroxyvitamin D3 on intestinal calcium absorption

Vitamin D and intestinal calcium transport after bariatric surgery

A Challenging Case of Hypocalcemia Supporting the Concept That 25-Hydroxyvitamin D Status Is Important for Intestinal Calcium Absorption

Contact Info

Product

Resources

About