Increased calcium intake reduces plasma cholesterol and improves vasorelaxation in experimental renal failure

Dietary Calcium-to-Phosphorous Ratio, Metabolic Risk Factors and Lipid Accumulation Product, Skeletal Muscle Mass, and Visceral Fat Area Among Healthy Young Individuals

BACKGROUND

Numerous studies have revealed the role of low dietary calcium-to-phosphorous ratio and low bone health. However, its possible role in visceral adiposity, skeletal muscle mass (SMM), and metabolic parameters has not been investigated before. Therefore, the aim of the current cross-sectional study was to evaluate the relation between dietary calcium-to-phosphorous ratio, metabolic risk factors, SMM, and visceral fat area (VFA) among physically active young individuals.

METHODS

In the current study, the sample was composed of 391 healthy young individuals (e.g., 205 men and 186 women), aged between 20 and 35 years old, who were engaged in moderate physical activity for at least 4 hr per week and were recruited thorough cluster sampling from seven sport clubs. Anthropometric measurements were performed, and VFA and SMM index (SMI) were calculated. Biochemical assays were also performed by standard kits. Data were analyzed by one-way analysis of variance, analysis of co-variance, and multinomial logistic regression analysis using SPSS software.

RESULTS

Those in the fourth quartile of dietary calcium-to-phosphorous ratio were more likely to have lower VFA (odds ratio [OR] = 0.98; 95% confidence interval [CI] [0.97, 0.99]; p = .023) and a nonsignificantly higher SMI (OR = 1.15; 95% CI [0.99, 1.34]; p = .058) after adjustment for the effects of confounders (e.g., age, gender, body mass index, physical activity level, dietary energy intake). Also, being in the third quartile of dietary calcium-to-phosphorous ratio made the subjects more susceptible to have lower insulin concentration (OR = 0.99; 95% CI [0.88, 0.93]; p = .026) in the adjusted model.

CONCLUSION

The findings of the current study revealed that a higher dietary calcium-to-phosphorous ratio in the habitual diet was negatively associated with visceral adiposity and insulin concentrations and higher SMM among physically active young individuals. Further interventional studies are required to confer causality that was not inferable in the current study because of cross-sectional design.

Unraveling the Mechanisms of Magnesium Supplementation in Alleviating Chronic Kidney Disease Complications and Progression: Balancing Risks and Benefits

Chronic kidney disease (CKD) is a major cause of death and disability worldwide. It is usually diagnosed at early levels because of its slow progression. Treatment should consider CKD complications (such as electrolyte level imbalance, vascular calcification, and bone mineral disorders), as well as the development of CKD itself. Large-scale studies have shown that current treatment guidelines are nearly ineffective and fail to achieve treatment goals. Guidelines have not paid as much attention to magnesium (Mg) as the other electrolytes, while Mg has a significant role in the treatment goals of CKD. Hypomagnesemia is the only electrolyte imbalance that is equally prevalent in all stages of CKD. A lower plasma Mg level in each stage of CKD is associated with a higher risk of CKD progression and cardiac events. Magnesium exerts its effects both directly and via other ions. Mg supplementation increases insulin sensitivity while reducing proteinuria and inflammation. It lowers blood pressure and inhibits vascular calcification primarily because of its effects on calcium and phosphate, respectively. Vitamin D supplementation for low-active vitamin D in CKD patients increases vascular calcification and cardiac events, but magnesium supplementation enhances vitamin D levels and activity without increasing the risk of cardiac events. However, careful attention is required due to the potential threats of hypermagnesemia, particularly in advanced CKD stages. Starting magnesium supplementation early in patients' treatment plans will result in fewer side effects and more advantages. More original research is needed to determine its optimal dose and serum levels.

Comparative Analysis of Dietary and Supplemental Intake of Calcium and Vitamin D among Canadian Older Adults with Heart Disease and/or Osteoporosis in 2004 and 2015

Despite the role of calcium and vitamin D in osteoporosis and heart disease, little research has examined changes in the intake of calcium and vitamin D among individuals with these conditions over time. Using data from the 2004 and 2015 Canadian Community Health Surveys, we investigated changes in dietary and supplemental intake of calcium and vitamin D among Canadian older adults aged ≥ 50 years, both with and without heart disease and/or osteoporosis, between 2004 and 2015. Notable declines in dietary calcium intake occurred, particularly among non-supplement users. Surprisingly, individuals with osteoporosis and heart disease, who are at higher nutritional risk, were less likely to use calcium supplements in 2015 compared to 2004. Among calcium supplement users, those with osteoporosis or both conditions experienced significant reductions in their usual calcium intake in 2015, with an increased proportion failing to meet recommended intake levels. Conversely, vitamin D supplement users experienced a substantial rise in vitamin D intake in 2015. In 2015, only a small proportion of supplement users did not meet the recommended vitamin D intake levels. These findings underscore the importance of public health initiatives to facilitate safe increases in calcium and vitamin D intake for older adults, particularly those with heart disease and osteoporosis.

Dietary calcium, magnesium, and phosphorus intakes and risk of stroke in Chinese adults

Controversial results have been reported about the association of calcium, magnesium, and phosphorus and stroke risk, but none in China. To investigate the association between dietary calcium, magnesium, phosphorus, and stroke incidence in Chinese adults, we collected data from the China Health and Nutrition Survey (CHNS) from 2004 to 2011, including 6411 participants aged 45-79 years and free of stroke at baseline. Diet was assessed by interviews combining 3-d 24-h food recalls and household food inventory weighing at each survey round. The stroke incident was identified based on the validated self-report. Multivariate Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). For 32,024 person-years of follow-up, 179 stroke cases were documented. After adjustment for major lifestyle and dietary risk factors, calcium intake was positively associated with reduced stroke risk, and the HR of stroke comparing extreme quartiles was 0.53 (95% CI 0.29-0.96, P_trend = 0.03). In further stratified analyses, significant heterogeneity across sex strata was found (P_interaction = 0.03). Dietary calcium intake among men was more inversely related to stroke, with HRs being 0.33 (95% CI 0.15-0.76, P _trend = 0.02), compared to 1.24 (95% CI 0.46-3.35, P_trend = 0.89) among women. However, no significant association between stroke and magnesium or phosphorus was revealed. Our findings suggest that higher dietary calcium intake was associated with a lower risk of stroke in Chinese adults, particularly in men.

Ergocalciferol improves endothelial vasodilatory and vasoconstrictor function in an in vivo model of mild uraemia

Endothelial dysfunction and vitamin D deficiency are prevalent in patients with cardiovascular disease (CVD) and chronic kidney disease (CKD). Both are risk factors for cardiovascular events in patients with CKD. No studies have investigated the effect of nutritional forms of vitamin D on endothelial function in earlier stages of CKD, when vascular endothelium may be more amenable to this therapy. We studied the effect of ergocalciferol in a pre-clinical model of mild uraemia.

Male Wistar rats underwent either a 5/6th nephrectomy or sham surgery. Four weeks after the final stage of the surgery, these two groups were randomly allocated to placebo or an oral dose of 1000 iu of ergocalcfierol at day 7 and 2 pre sacrifice. Vascular responses to acetylcholine, Spermine NONOate and phenylephrine were determined in aortic rings. Blood pressure, calcium, phosphate and parathyroid hormone were measured in all groups.

Ergocalciferol significantly improved the endothelium-dependent responses to acetylcholine and overcame the blunting of the contractile response to phenylephrine seen in uraemic animals. Ergocalciferol improved the contractile response to potassium chloride in uraemic, but not sham animals. All effects occurred independently of changes to calcium, phosphate, parathyroid hormone and systolic blood pressure. There were no differences in endothelium-independent relaxation to Spermine NONOate.

In summary, in a model of mild uraemia, ergocalciferol improved vasodilator and vasoconstrictor tone independently of blood pressure and bone mineral parameters suggesting a direct effect of ergocalciferol on the endothelium.

Association of Angiotensin-Converting Enzyme Insertion/Deletion Polymorphism with the Risk of Atherosclerosis

AIMS

The objective of this study was to perform a meta-analysis to evaluate the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and susceptibility to atherosclerosis (AS).

METHODS

MEDLINE, EMBASE, and the ISI Web of Science were searched for all eligible published studies concerning the relationship of ACE gene polymorphism with AS without language restrictions. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate this relationship under different genetic models using meta-analytic methods.

RESULTS

A total of 15 articles (16 studies) were involved in this meta-analysis. The D allele of the ACE gene had a nonsignificant increase in the risk of AS (D versus I: OR = 1.23, 95% CI, .98-1.53, P = .07; I² = 87.2%, P_{heterogeneity} < .01). Compared with the II genotype, the DI (relative risk [RR]: 1.35, 95% CI: 1.09, 1.67, P < .01; I² = 47.8%, P_{heterogeneity} = .017) and (DD + DI) (RR = 1.38, 95% CI: 1.04, 1.82, P = .02; I² = 73.3%, P_{heterogeneity} < .01) genotype of ACE was associated with higher risk of AS, respectively. Subjects with the DD genotype showed a statistically nonsignificant trend toward greater risk of AS (RR = 1.53, 95% CI: .97, 2.43, P = .07; I² = 88.6%, P_{heterogeneity} < .01). Further subgroup analyses showed that significant relationships were only found in Europeans under different gene polymorphism or different genotype models rather than Asians.

CONCLUSIONS

The present meta-analysis indicated that the D allele in the ACE gene was associated with the risk of AS, especially in Europeans. Furthermore, increased copy number of D allele was significantly associated with increased AS risk in a dose-dependent manner.

Effects of calcium-vitamin D co-supplementation on metabolic profiles in vitamin D insufficient people with type 2 diabetes: a randomised controlled clinical trial

AIMS/HYPOTHESIS

This study was performed to assess the effects of vitamin D and calcium supplementation on the metabolic profiles of vitamin D insufficient persons with type 2 diabetes.

METHODS

In a parallel designed randomised placebo-controlled clinical trial, a total of 118 non-smoker individuals with type 2 diabetes and insufficient 25-hydroxyvitamin D, aged >30 years, were recruited from the Isfahan Endocrine and Metabolism Research Centre. Participants were randomly assigned to four groups receiving: (1) 50,000 U/week vitamin D + calcium placebo; (2) 1,000 mg/day calcium + vitamin D placebo; (3) 50,000 U/week vitamin D + 1,000 mg/day calcium; or (4) vitamin D placebo + calcium placebo for 8 weeks. A study technician carried out the random allocations using a random numbers table. All investigators, participants and laboratory technicians were blinded to the random assignments. All participants provided 3 days of dietary records and 3 days of physical activity records throughout the intervention. Blood samples were taken to quantify glycaemic and lipid profiles at study baseline and after 8 weeks of intervention.

RESULTS

30 participants were randomised in each group. During the intervention, one participant from the calcium group and one from the vitamin D group were excluded because of personal problems. Calcium-vitamin D co-supplementation resulted in reduced serum insulin (changes from baseline: -14.8 ± 3.9 pmol/l, p = 0.01), HbA1c [-0.70 ± 0.19% (-8.0 ± 0.4 mmol/mol), p = 0.02], HOMA-IR (-0.46 ± 0.20, p = 0.001), LDL-cholesterol (-10.36 ± 0.10 mmol/l, p = 0.04) and total/HDL-cholesterol levels (-0.91 ± 0.16, p = 0.03) compared with other groups. We found a significant increase in QUICKI (0.025 ± 0.01, p = 0.004), HOMA of beta cell function (HOMA-B; 11.8 ± 12.17, p = 0.001) and HDL-cholesterol (0.46 ± 0.05 mmol/l, p = 0.03) in the calcium-vitamin D group compared with others.

CONCLUSIONS/INTERPRETATION

Joint calcium and vitamin D supplementation might improve the glycaemic status and lipid profiles of vitamin D insufficient people with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01662193 FUNDING: Clinical Research Council, Isfahan University of Medical Sciences, Isfahan, Iran.

Impact of diet on mortality from stroke: results from the U.S. multiethnic cohort study

OBJECTIVES

Stroke is the fourth leading cause of death in the United States and stroke mortality rates vary by ethnicity. The purpose of this study was to examine the associations between food group consumption and risk of death from stroke among 5 ethnic groups in the United States.

METHODS

The Multiethnic Cohort includes >215,000 participants, the majority of whom are African American, Native Hawaiian, Japanese American, Latino, and Caucasian men and women recruited by mail survey in Hawaii and Los Angeles in 1993-1996. Deaths from stroke were identified by linkage to the state death files and the U.S. National Death Index. Diet was assessed using a validated food frequency questionnaire. Associations were examined using multivariable Cox proportional hazards models, stratified by ethnicity and gender.

RESULTS

A total of 860 deaths from stroke were identified among the cohort participants. Vegetable intake was associated with a significant reduction in risk for fatal stroke among African American women (relative risk [RR]=0.60; 95% CI: 0.36-0.99). Among Japanese American women only, high fruit intake was significantly associated with a risk reduction for stroke mortality (RR=0.43; 95% confidence interval [CI]: 0.22-0.85), whereas meat intake increased risk (RR=2.36; 95% CI: 1.31-4.26). Among men, a significant reduction in stroke mortality was observed among Native Hawaiians (RR=0.26; 95% CI: 0.07-0.95). After pooling the data for the ethnic groups, the findings support an elevated risk for high meat intake among women overall (RR=1.56; 95% CI: 1.12-2.16); no significant effects of dietary intake on risk for fatal stroke were observed among men.

CONCLUSIONS

Although some variations were observed for the associations between diet and stroke mortality among ethnic groups, the findings suggest that these differences are not substantial and may be due to dietary intake of specific food subgroups. Additional investigations including dietary subgroups and nutrients sources are needed to clarify these findings.

Effect of calcium treatment on blood parameters, gonadal development and the structure of bone in immature female rats

Calcium is an essential nutrient required for critical biological functions. Calcium supplementation is to be evaluated using immature female rats. The present study focused on some blood parameters, gonadal development and bone structure. Forty immature female Sprague-Dawley rats were randomly divided into four equal-sized groups (80 g average body weight) to receive calcium chloride dihydrate (group I: control; groups II, III and IV: received 20 mg, 40 mg and 60 mg per kg body weight, respectively) for 5 weeks. Rats were decapitated, and their trunk blood was sampled for biochemical assays. Cholesterol, triglycerides, glucose and calcium were measured. Gonadal and bone structure were histologically evaluated. Results revealed that treatment of developing female rats with three calcium doses used have no marked effect on the serum calcium and cholesterol levels. However, serum triglyceride level and body weight gain are significantly decreased in rats treated with all of the three calcium doses. Serum glucose level showed a marked increase in animals treated with the higher calcium doses. Moreover, observable histological alterations are recognized in the ovaries. Bones of the experimental animals also showed morphological alterations. These results suggest that increasing calcium supplementation decreases triglycerides and percentage body weight gain and positively affects the bone and gonadal development.

Multiple antioxidants and L-arginine modulate inflammation and dyslipidemia in chronic renal failure rats

The kidney is an important source of L-arginine, the endogenous precursor of nitric oxide (NO). Surgical problems requiring extensive renal mass reduction (RMR) decrease renal NO production, leading to multiple hemodynamic and homeostatic disorders manifested by hypertension, oxidative stress, and increased inflammatory cytokines. Using the RMR model of chronic renal failure (CRF), we assessed the effects of twelve weeks' administration of L-arginine and/or a mixture of antioxidants (L-carnitine, catechin, vitamins E and C) on plasma cytokines, soluble intercellular adhesion molecule-1 (sICAM-1), nitrate and nitrites (NO(2)/NO(3)), lipid profile, blood pressure, and renal function. CRF rats showed increased plasma IL-1 alpha, IL1-beta, IL-6, TNF-alpha, and sICAM-1 levels and decreased anti-inflammatory cytokines IL-4 and 10 levels, hypertension, and dyslipidemia. L-arginine treatment improved kidney functions, decreased systolic blood pressure, and decreased inflammatory cytokines levels. Antioxidants administration decreased inflammatory cytokines and sICAM-1 levels and increased IL-4 levels. Combined use of both L-arginine and the antioxidant mixture were very effective in their tendency to recover normal values of kidney functions, plasma cytokines, sICAM-1, blood pressure, NO(2)/NO(3), cholesterol, and triglycerides concentrations. Indeed, the effects of L-arginine and the antioxidants on the reduction of proinflammatory cytokines may open new perspectives in the treatment of uremia.

Effect of 5 y of calcium plus vitamin D supplementation on change in circulating lipids: results from the Women's Health Initiative

BACKGROUND

Dietary calcium and vitamin D intakes may be inversely associated with cardiovascular disease (CVD) risk, possibly because of their potential beneficial effects on circulating lipids. Clinical trials that have evaluated the effect of calcium supplementation on lipids are limited by a short follow-up, and data on vitamin D are scarce.

OBJECTIVE

The objective was to evaluate the effect of a longer-term effect (over 5 y) of calcium and vitamin D (CaD) supplementation on changes in the concentrations of several lipids: LDL, HDL, non-HDL, total cholesterol, triglycerides, and lipoprotein(a) [Lp(a)].

DESIGN

The study was conducted in 1259 postmenopausal women in the Calcium plus Vitamin D Trial (1 g elemental Ca as carbonate plus 400 IU vitamin D(3)/d compared with placebo) of the Women's Health Initiative. Analyses were conducted by intention-to-treat. Repeated measurements on lipids during follow-up were analyzed by linear mixed-effects models.

RESULTS

Overall, the change in lipids was relatively small [< or =5% except for Lp(a), which was 20-25%], and there was no significant difference in the mean change of any lipid variable between the active and placebo groups.

CONCLUSIONS

Our results indicate that CaD supplementation is not associated with lipid changes over 5 y. Existing and future CaD trials should consider evaluating this association for different doses of supplements. This study was registered at clinicaltrials.gov as NCT00000611.

Fat redistribution and adipocyte transformation in uninephrectomized rats

Dyslipidemia complicates renal function leading to disturbances of major homeostatic organs in the body. Here we examined the effect of chronic renal dysfunction induced by uninephrectomy on fat redistribution and lipid peroxidation in rats treated with an angiotensin-converting enzyme (ACE) inhibitor (lisinopril) for up to 10 months. Uninephrectomized rats developed fat redistribution and hypercholesterolemia typical of chronic renal failure when compared with sham-operated rats or lisinopril-treated uninephrectomized rats. The weight of the peri-renal fat was significantly less in the untreated compared to the lisinopril-treated uninephrectomized rats or those rats with a sham operation. We also found that there was a shift of heat-protecting unilocular adipocytes to heat-producing multilocular fat cells in the untreated uninephrectomized rats. Similarly in these rats we found a shift of subcutaneous and visceral fat to ectopic fat with excessive lipid accumulation and lipofuscin pigmentation. Lisinopril treatment prevented fat redistribution or transformation and lipid peroxidation. This study shows that ACE inhibition may prevent the fat anomalies associated with chronic renal dysfunction.