The Role of Dietary Calcium in the Physiology of Vitamin D Toxicity: Excess Dietary Vitamin-D3 Blunts Parathyroid Hormone Induction of Kidney 1-Hydroxylase

1995 ◽  
Vol 319 (2) ◽  
pp. 535-539 ◽  
Author(s):  
M.J. Beckman ◽  
J.A. Johnson ◽  
J.P. Goff ◽  
T.A. Reinhardt ◽  
D.C. Beitz ◽  
...  
Author(s):  
Sanjeeva Kumar Goud T ◽  
Rahul Kunkulol

The present study was aimed to study the effect of Sublingual Vitamin D3 on Serum Vitamin D level in Vitamin D deficiency patients. This was a cross-sectional and interventional study. All the Vitamin D deficiency patients of age 18-60years and either gender, willing to participate in the study were included. Patients who had greater than 20 ng/ml were excluded from the study. The total number of participants in our study was 200, out of these 111 males and 89 females, the mean age in our study was 51.07 ± 7.39Yrs. All volunteers were given sublingual vitamin D3 (60,000IU) in six doses every fifteen days of follow up for 3 months. The subject’s serum 25(OH)D levels were estimated before and after the treatment of sublingual vitamin D3. There was a statistically significant difference in serum vitamin D3 level before 16.61±6.71 ng/ml and after 35.80±7.80 ng/ml after treatment with Sublingual Vitamin D3. Six doses of 60,000IU of Vitamin D3 sublingual route having improved the role of serum 25(OH)D levels in the treatment of Vitamin D3 deficiency patients.Keywords: Vitamin D3; Sublingual route


1981 ◽  
Vol 241 (1) ◽  
pp. G49-G53
Author(s):  
N. Brautbar ◽  
B. S. Levine ◽  
M. W. Walling ◽  
J. W. Coburn

The intestinal absorption of calcium (Ca) has been shown to depend on vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and dietary phosphorus (P) concentration. This study was designed to evaluate the role of dietary P independent of vitamin D3 or 1,25(OH)2D3. Vitamin D-deficient rats were studied during dietary P restriction and were compared with control groups raised on a normal-phosphorus diet (NP). Balance studies were sued. Net intestinal Ca absorption was significantly lower with dietary P restriction compared with the NP group. This malabsorption of Ca was corrected by the administration of either D3 for 1,25(OH)2D3, despite hypophosphatemia. Everted gut sacs showed a marked reduction in the uptake of 45Ca in the duodenum, jejunum, and ileum during dietary P restriction. We concluded that dietary P concentration plays a major role in intestinal Ca absorption in the vitamin D-deficient rats. These findings suggest an effect of the low-phosphate diet on the vitamin D-dependent, Ca-transport mechanism.


Nutrients ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1743 ◽  
Author(s):  
Valeria Polzonetti ◽  
Stefania Pucciarelli ◽  
Silvia Vincenzetti ◽  
Paolo Polidori

Background: Vitamin D and calcium are important dietary compounds that affect bone mass, even if other minerals (potassium, zinc, etc.) and vitamins (A, C and K) are also involved. Vitamin D and certain minerals, in fact, play an important role in calcium homeostasis and calcium absorption. Hip fracture incidence is higher in Europe and the United States, where calcium is frequently included in the human diet; while the occurrence of these fractures is lower in developing countries, where diets are often poor in calcium. This condition is named the “calcium paradox”, and may be partially explained by phosphate toxicity, which can negatively affect mineral metabolism. It is important to maintain correct dietary calcium-phosphate balance in order to have a healthy life, reducing the risk of osteoporotic fractures in older people. Vitamin D can also act as a hormone; vitamin D2 (ergocalciferol) is derived from the UV-B radiation of ergosterol, the natural vitamin D precursor detected in plants, fungi, and invertebrates. Vitamin D3 (cholecalciferol) is synthesized by sunlight exposure from 7-dehydrocholesterol, a precursor of cholesterol that can also act as provitamin D3. Dietary intake of vitamin D3 is essential when the skin is exposed for short periods to ultraviolet B light (UV-B), a category of invisible light rays such as UV-A and UV-C. This can be considered the usual situation in northern latitudes during the winter season, or the typical lifestyle for older people and/or for people with very white delicate skin. The actual recommended daily intake of dietary vitamin D is strictly correlated with age, ranging from 5 μg for infants, children, teenagers, and adults—including pregnant and lactating women—to 15 μg for people over 65 years.


2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Chan Yoon Park ◽  
Yongho Shin ◽  
Jeong-Han Kim ◽  
Sung Nim Han

Abstract Objectives Vitamin D deficiency is often observed in obese person. One of the mechanisms suggested is the decreased bioavailability of vitamin D due to its deposition in adipose tissue. We investigated the effects of obesity on vitamin D distribution by measuring 25(OH)D levels in circulation and comparing vitamin D content in liver and adipose tissue from obese and control mice fed different levels of vitamin D. Methods Six-wk-old C57BL/6 mice were fed control or high fat (10 or 45% kcal fat, CON or HFD) diets containing different levels of vitamin D3 (1000, or 25,000 IU/kg of diet, CVd or HVd) for 13 wks. Serum 25-hydroxyvitamin D (25(OH)D) level was determined by radioimmunoassay. Vitamin D3 and 25(OH)D3 levels in the liver and epididymal adipose tissue (AT) were quantified by LC-MS/MS. mRNA levels of liver Cyp2r1 and Cyp27a1 were determined by real-time PCR. Results Overall, serum 25(OH)D levels were significantly higher in the HVd groups compared with CVd groups. There was no difference in serum 25(OH)D levels between CON-CVd and HFD-CVd groups. However, in the vitamin D supplemented groups, HFD-HVd group had significantly lower serum 25(OH)D levels (20% lower) than CON-HVd group. Vitamin D3 levels in the liver and AT were 55 and 100 times higher in the HVd groups (liver and AT: 719 and 318 ng/g tissue) compared with the CVd groups. 25(OH)D3 levels in the liver and AT were also 3.3 and 2.4 times higher in the HVd groups (liver and AT: 33.9 and 18.9 ng/g tissue) than those of the CVd groups. Total amount of vitamin D3 in the liver and AT were significantly higher in the HFD-HVd group (121 and 44% higher) compared with CON-HVd group. However, when mice were fed the control levels of vitamin D, dietary fat levels did not affect the vitamin D3 amount in the liver and AT. Liver Cyp2r1 and Cyp27a1 mRNA levels did not differ among groups. Conclusions When vitamin D intake was at a supplementation level, a significant amount of dietary vitamin D seemed to be stored in the liver and AT; thus excess body adiposity could contribute to lower serum 25(OH)D level. However, at a control level of vitamin D intake, obesity did not affect tissue vitamin D amount and serum 25(OH)D levels. Funding Sources Supported by the grant from the National Research Foundation (NRF) of Korea (NRF-2018R1D1A1B070491) and Research Grant from Research Affairs at Seoul National University.


1985 ◽  
pp. 591-595
Author(s):  
Gary S. Rogoff ◽  
Roger B. Galburt ◽  
Abraham E. Nizel

Author(s):  
Grenville Fox ◽  
Nicholas Hoque ◽  
Timothy Watts

This chapter explains the embryology of sexual differentiation, which provides the basis to assessment and management of disorders of sexual differentiation presenting at birth. There are sections on neonatal adrenal insufficiency and pituitary insufficiency, with background information provided on fetal and neonatal physiology relevant to these. Thyroid disorders are explained with particular reference to maternal thyroid disease. Calcium disorders and fetal and neonatal bone metabolism are explained, including the role of calcitonin, vitamin D, and parathyroid hormone.


Author(s):  
Francesco Trepiccione ◽  
Giovambattista Capasso

Ca2+ homeostasis is achieved through a fine balance among three main organs: the intestine, the kidney, and bone. Blood levels of Ca2+ are accurately tuned through the Ca2+ sensing receptors and regulated by several hormones, including parathyroid hormone (PTH), active vitamin D, and calcitonin. The most recent findings in Ca2+ handling are described. The role of the Ca2+ sensing receptor, as well as Klotho, a new player participating in Ca2+ homeostasis, are described. Finally, the effects of diuretics, calcineurin inhibitors, and the link between hypertension and Ca2+ metabolism are reviewed.


2020 ◽  
Vol 79 (OCE2) ◽  
Author(s):  
Cai-Xia Zhang ◽  
Xin Zhang ◽  
Hong Luo ◽  
Xiao-Li Feng ◽  
Nai-Qi Zhang

AbstractIntroductionThe effect of dietary vitamin D, calcium and dairy products intake on colorectal cancer risk is controversial. This study aims to investigate the associations between dietary vitamin D, calcium, dairy products intake and colorectal cancer risk among Chinese population.Materials and MethodsDuring July 2010 to December 2018, 2380 incident, first primary, histologically confirmed colorectal cancer cases and 2389 sex and age-matched (5-year interval) controls were recruited. Dietary intake information was collected by face-to-face interviews using a validated food frequency questionnaire. Energy and other nutrient intakes such as dietary calcium were computed on the basis of the 2002 Chinese Food Composition Table, and the dietary vitamin D intake was calculated according to the United States Department of Agriculture Food Composition Database. Unconditional multivariable logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence interval (CI) after adjusting for various confounders, including socio-demographic characteristics, lifestyle factors, BMI, family history of cancer, energy intake and several nutrient intakes.ResultsThe energy-adjusted mean dietary vitamin D, calcium and total dairy products intakes were 5.69μg/d, 406.94mg/d, 4.02g/d for cases and 6.81μg/d, 468.21mg/d, 9.50g/d for controls. Compared with the controls, cases had a lower intake of dietary vitamin D, calcium and total dairy (P < 0.001). A higher intake of dietary vitamin D and calcium was found to be associated with 43% and 51% reduction in colorectal cancer. The ORs of the highest quartile compared with the lowest quartile intake were 0.57 (95% CI: 0.46, 0.70, Ptrend < 0.001) for dietary vitamin D and 0.49 (95% CI: 0.39, 0.61, Ptrend < 0.001) for dietary calcium. We observed a statistically significant inverse association of dairy products intake with colorectal cancer risk. Compared with the lowest tertile, the adjusted ORs for the highest tertile were 0.31 (95% CI: 0.26, 0.38, Ptrend < 0.001) for total dairy. The inverse associations of dietary vitamin D, calcium and dairy products intakes with colorectal cancer risk were observed in both men and women, colon and rectal cancer.ConclusionOur study indicated that higher dietary vitamin D, calcium and dairy products intakes were associated with a lower colorectal cancer risk.


1983 ◽  
Vol 244 (6) ◽  
pp. F674-F678 ◽  
Author(s):  
M. M. Friedlaender ◽  
Z. Kornberg ◽  
H. Wald ◽  
M. M. Popovtzer

The effects of 1 alpha (OH)vitamin D3 [1 alpha (OH)D3] and 24,25(OH)2vitamin D3 [24,25(OH)2D3] on the phosphaturic action of parathyroid hormone (PTH) were studied in two groups of parathyroidectomized (PTX) rats. In group 1, PTX PTH-infused rats received intravenous 1 alpha (OH)D3, and in group 2, PTX PTH-infused rats received intravenous 24,25(OH)2D3. PTX PTH-infused rats served as controls. The effects of both vitamin D metabolites on renal PTH-activated adenylate cyclase (AC) were studied in vitro. In group 1, PTH increased fractional excretion of phosphate (CP/CIn) from 0.045 +/- 0.012 (+/- SE) to 0.263 +/- 0.011 (P less than 0.005). 1 alpha (OH)D3 failed to influence this response. In group 2, PTH increased CP/CIn from 0.055 +/- 0.008 to 0.289 +/- 0.027 (P less than 0.005). 24,25(OH)2D3 reduced the PTH-induced rise in CP/CIn from 0.289 +/- 0.027 to 0.192 +/- 0.021 (P less than 0.01) and decreased the urinary excretion of adenosine 3',5'-cyclic monophosphate. In vitro, 24,25(OH)2D3 blunted the PTH-activated AC, whereas 1 alpha (OH)D3 had no effect. These results show that 24,25(OH)D3, similar to two other 25(OH) metabolites of vitamin D-25(OH)vitamin D3 and 1,25(OH)2vitamin D3-suppresses the phosphaturic action of PTH, whereas 1 alpha(OH)D3, which is devoid of a 25(OH) group, lacks this effect. This suggests that a 25(OH) group is a prerequisite for the antiphosphaturic effect of vitamin D, whereas the 1 alpha (OH) group is not essential for this action.


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