Effect Of Oral Calcium Research Articles

The effects of oral calcium on the prevention of moderate to severe ovarian hyperstimulation syndrome in high-risk patients: A placebo-controlled study

Ovarian Hyperstimulation Syndrome (OHSS) is a serious complication of Assisted Reproductive Technology (ART). Some studies show that intravenous calcium infusion decreases the risk of OHSS in high-...

Close look at the effects of oral calcium on hypertension

Close look at the effects of oral calcium on hypertension

Calcium regulation of colonic crypt cell kinetics: Evidence for a direct effect in mice

Background & Aims: Oral calcium supplementation is believed to decrease colonic hyperproliferation through neutralization of fatty acids and bile acids. In the present study, the effect of oral calcium, given with low-fat diets, in the early stages of colorectal carcinogenesis is evaluated. Methods: In experiment A, mice received normal or low-calcium diets and were killed at 25 weeks. In experiment B, mice were fed the same diets but were submitted to six weekly injections of dimethylhydrazine and were killed at 10, 16, and 21 weeks. Cell proliferation was evaluated using bromodeoxyuridine immunohistochemistry. Results: In experiment A, mice fed low-calcium diets showed a significant upward shift of the proliferative compartment ( P = 0.04) (phase 2 defect) in the absence of hyperproliferation. In experiment B, besides a phase 2 defect, dimethylhydrazine-induced hyperproliferation was also significantly enhanced in animals fed low-calcium diets (phase 1 defect) as shown by an increased number of labeled cells per column and total labeling index ( P = 0.01). Conclusions: Low-calcium diets induce an upward shift of the main proliferative compartment, which reflects an increased risk for malignant transformation. This effect was observed with a low-fat diet, suggesting a direct mechanism, rather than the usual indirect one, documented with high-fat diets.

Effects of oral calcium and potassium on endothelium-dependent relaxation in hypertensive rats.

High oral potassium (K) decreases stroke incidence in aging high salt-fed stroke-prone spontaneously hypertensive rats (SHRSP). We have seen high oral Ca increase stroke incidence in aging high salt-fed SHRSP without increasing blood pressure (BP) but with signs of K wasting. Therefore, we sought to determine whether high oral Ca suppresses the previously reported oral K-related enhancement of arterial endothelium-dependent relaxation as seen in younger high salt-fed SHRSP before the appearance of strokes. Four groups of female SHRSP were fed high-salt diets containing either low (0.4%) or high (1.6%) K with low (0.4%) and high (1.6%) Ca from age 1 to 4 mos. High oral K decreased BP independent of Ca intake (P < 0.05). High oral Ca did not affect BP. In contrast to aging SHRSP, high oral Ca neither increased urinary excretion nor decreased plasma concentration of K in these young adult SHRSP. However, high (vs. low) oral K only significantly reduced the half-maximal effective dose for acetylcholine-induced relaxation of aortic rings from rats fed low (18 +/- 3 vs. 38 +/- 6 nM, P < 0.05) not high Ca (25 +/- 5 vs. 31 +/- 3 nM). Neither oral K nor Ca affected nitroprusside-induced relaxation. Thus high oral Ca by itself does not impair endothelium-dependent relaxation in young adult high salt-fed SHRSP, but yet it suppresses the enhancing effect of high oral K on such relaxation and does so without altering BP, K balance, or endothelium-independent relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of oral calcium medication on nasal resistance in the nasal allergen provocation test

Although calcium has been used for several decades to treat allergic diseases of the skin and respiratory tract, controlled studies demonstrating the action of oral preparations in allergic rhinitis are lacking. This placebo-controlled, double-blind, crossover study shows that 1000 mg calcium administered orally significantly inhibits the allergen-induced swelling of the nasal mucosa in the allergen provocation test. Sneezing and secretion, which are allergic symptoms, were not reduced. This study is the first to confirm the positive effect of oral calcium on a symptom of allergic rhinitis.

Contrasting Hemodynamic Effects of High Oral Calcium in Genetic Models of Salt-Sensitive Hypertension

Interest in effects of oral calcium (Ca) on blood pressure is now generally focused on salt-induced hypertension. In this study hemodynamic effects of long-term high oral Ca were examined in two different genetic models of salt-sensitive hypertension, stroke-prone spontaneously hypertensive rats (spSHR) and Dahl salt-sensitive (DS) hypertensive rats. High vs low oral Ca (2.0 vs 0.4% Ca, 8-13 rats/diet) significantly (p less than 0.05) attenuated salt-induced hypertension (7% NaCl intake) in female spSHR (mean arterial pressure = 137 vs 175 mmHg) but aggravated such hypertension in female DS rats (141 vs 124 mmHg). Pressor responsiveness to norepinephrine (NE) and angiotensin (A) II were examined in the same rats. High oral Ca decreased pressor responses to graded intravenous injections of NE and AII in spSHR and increased such responses in DS rats. In spSHR, the decreased pressor responsiveness preceded the antihypertensive effect of high oral Ca. In summary, 2.0 vs 0.4% oral Ca produces contrasting effects on blood pressure in two genetic models of salt-sensitive hypertension (stroke-prone SHR and Dahl salt-sensitive rats). These contrasting effects on blood pressure may be related to differential effects of oral Ca on vascular responsiveness to endogenous vasoconstrictors in these two genetic models of salt-sensitive hypertension.

Calcium Treatment of Enteric Hyperoxaluria after Jejunoileal Bypass for Morbid Obesity

The effect of oral calcium on oxalate absorption was studied in eight patients with secondary hyperoxaluria after jejunoileal bypass for morbid obesity during a standardized diet with a fixed supply of fat, calcium, and oxalate. A supplementary calcium dose of 2000 mg/day reduced renal oxalate excretion from 119 to 60 mg/24 h (median values, p < 0.01). Correspondingly, 14C-oxalate absorption decreased from 28% to 9% (p < 0.01). No statistically significant increase in urinary calcium was observed. The study shows that renal oxalate excretion in patients with enteric hyperoxaluria can be reduced by oral calcium. However, we doubt that it has any practical, clinical importance.

The effect of calcium on plasma lipids and bile acid and fecal fat excretion in normolipidemic subjects

The effect of oral calcium (2 g/day) was studied in four normolipidemic subjects. Calcium caused a significant lowering of plasma cholesterol and a considerable fall in the glycine-/taurine-conjugated bile acid ratio in the intestinal aspirate of one subject, while fecal bile acid excretion rose appreciably in another during treatment. These parameters showed no consistent trend in the other three subjects. None of the subjects showed any significant change in plasma triglycerides and serum calcium and phosphorus during treatment. One subject showed a consistent decrease in every parameter studied throughout the experiment, a trend which was probably due to a concomitant loss in body weight.

The effect of oral calcium on cholesterol metabolism

The effects of calcium on cholesterol metabolism have been examined in 6 patients. The age of the subjects ranged from 61–73 years. Five of the patients were osteoporotic. The calcium was administered as organic salts (calcium glycerophosphate or calcium gluconogalactogluconate) and as dried skimmed milk. The results show that increased calcium in the organic form caused increased excretion of faecal bile acids and faecal total fat. There was no change in faecal neutral steroid output; increased faecal cholesterol was compensated by decreased coprostanol excretion. When the calcium was given in the form of skimmed milk, faecal bile acids and faecal fat remained elevated. Faecal excretion of cholesterol continued to rise and was accompanied by the return of faecal coprostanol output almost to the basal level, resulting in increased total neutral steroid excretion. The serum cholesterol and triglyceride levels showed little change from the basal levels during the calcium supplementation periods.

EFFECTS OF ORAL CALCIUM UPON SERUM LIPIDS IN MAN.

EFFECTS OF ORAL CALCIUM UPON SERUM LIPIDS IN MAN.