The role of calcium in the prevention of kidney stones

A Simple Laser-Induced Breakdown Spectroscopy Method for Quantification and Classification of Edible Sea Salts Assisted by Surface-Hydrophilicity-Enhanced Silicon Wafer Substrates

Salt, one of the most commonly consumed food additives worldwide, is produced in many countries. The chemical composition of edible salts is essential information for quality assessment and origin distinction. In this work, a simple laser-induced breakdown spectroscopy instrument was assembled with a diode-pumped solid-state laser and a miniature spectrometer. Its performances in analyzing Mg and Ca in six popular edible sea salts consumed in South Korea and classification of the products were investigated. Each salt was dissolved in water and a tiny amount of the solution was dropped and dried on the hydrophilicity-enhanced silicon wafer substrate, providing homogeneous distribution of salt crystals. Strong Mg II and Ca II emissions were chosen for both quantification and classification. Calibration curves could be constructed with limits-of-detection of 87 mg/kg for Mg and 45 mg/kg for Ca. Also, the Mg II and Ca II emission peak intensities were used in a k-nearest neighbors model providing 98.6% classification accuracy. In both quantification and classification, intensity normalization using a Na I emission line as a reference signal was effective. A concept of interclass distance was introduced, and the increase in the classification accuracy due to the intensity normalization was rationalized based on it. Our methodology will be useful for analyzing major mineral nutrients in various food materials in liquid phase or soluble in water, including salts.

The effect of nutritional factors on urolithiasis: A case-control study

Urolithiasis, a prevalent chronic kidney disease affecting all age groups, can be influenced by nutritional factors. The incidence of urolithiasis in Asian countries ranges from 1% to 19.1%, attributed to geographical and lifestyle differences. In Iran, several risk factors, including ethnicity, dietary habits, gender, and age, are associated with urolithiasis. This study aimed to assess the impact of nutritional factors on kidney and urinary tract stone formation. This case-control study enrolled 127 newly diagnosed urolithiasis patients, and 127 matched healthy participants between February to May 2017. Exclusion criteria included diabetes and acute or chronic renal failure. Data were collected using the Food Frequency Questionnaire (FFQ) and analyzed using chi-square and logistic regression tests. Water (95% CI: 0.09-0.89, OR=0.28), natural juices (95% CI: 0.10-0.65, OR=0.53), mineral water (95% CI: 0.05-0.64, OR=0.18), legumes (95% CI: 0.00-0.38, OR=0.032), butter, cream, or peppermint (95% CI: 0.09-0.95, OR=0.30), and ice cream (95% CI: 0.07-0.54, OR=0.203) had a significant protective effect against kidney and urinary tract stone formation. Conversely, tea consumption (95% CI: 1.15-7.99, OR=4.70), beverages (95% CI: 4.45-23.32, OR=23.32), coffee (95% CI: 1.63-11.78, OR=4.39), bread (95% CI: 1.1-10.59, OR=3.37), meat (95% CI: 1.01-8.01, OR=2.85), liver (95% CI: 3.37-488.90, OR=40.58), fish (95% CI: 2.89-216.39, OR=25.03), and various canned foods (95% CI: 1.34-10.25, OR=3.70) were significantly associated with kidney and urinary tract stone risk. These findings showed that the risk of urinary stones formation had a significant relationship with dietary habits. Therefore, the correct dietary pattern and sufficient fluid consumption may play an important role in preventing urinary stones.

Food-Borne Nanocarriers for Calcium Delivery: A New Choice for Nutrient Supplements

Calcium is considered as an important nutrient element for the maintenance of human health, and food-borne nanoparticles (FNs) produced during food processing may have potential as nanocarriers for calcium ion delivery. Beef is an important source of animal protein that has high protein and low fat content and is rich in a variety of amino acids; thus, beef may be a suitable material for the development of calcium nanocarriers. In this paper, FNs were synthesized from beef by one-step hydrothermal synthesis. The FNs had a spherical shape with a size of about 3.0 nm and emitted a bright blue fluorescence under 365 nm ultraviolet irradiation. The amino nitrogen atom and carboxyl oxygen atom of the functional groups on the surface of the FNs were the main binding sites for the chelation of Ca(II). The size of the FNs-Ca(II) complex was about 4.75 nm, and the specific signal peak of calcium at 3.7 keV was observed in its energy dispersive X-ray spectroscopy spectrum. The viability of cells treated with FNs-Ca(II) was more than 65%, while viability was only 60% after treatment with CaCl₂. The results showed that the FNs from beef have great potential in calcium delivery for the development of a calcium supplement.

Feasibility of Quantitative Analysis of Magnesium and Calcium in Edible Salts Using a Simple Laser-Induced Breakdown Spectroscopy Device

Feasibility of a simple laser-induced breakdown spectroscopy (LIBS) device has been investigated for the analysis of Mg and Ca in edible salts. The LIBS spectrometer was assembled with a compact low-power diode-pumped solid-state laser (DPSSL) and a non-gated low-resolution handheld spectrometer. A simple sampling process was employed for on-site application. A piece of filter paper was dipped in the aqueous solution of a sample salt and dried for analysis using LIBS. Maintaining the sample surface height at the optimum position was critical to generate plasmas persistently due to the low pulse energy of the DPSSL. The varying height of the filter paper surface was monitored and compensated, while the sample stage was translated to collect spectra from different positions. The variation of line intensities of Mg and Ca could be attributed to the inhomogeneous distribution of dry residues. To correct this, the peak that consists of the Na(I) and C(II) lines at 568 nm was employed as a reference signal for intensity normalization of the analyte Mg(II) and Ca(II) lines. For edible salt products, the normalized Mg(II) and Ca(II) line intensities could be well correlated with the concentrations of Mg and Ca determined using inductively coupled plasma optical emission spectroscopy. Our results indicate that a simple LIBS device in combination with the simple sampling method is promising as an on-site salt quality assessment methodology.

Dietary risk factors for urolithiasis in Korea: A case-control pilot study

Purpose

Dietary factors are one of the main causes of urolithiasis. However, little research has evaluated dietary factors related to urolithiasis in Korea. We investigated the various dietary risk factors for urinary stone formation in Korean people.

Materials and Methods

We conducted a prospective case-control pilot study. A total of 27 patients newly diagnosed with urolithiasis and 20 applicants without urolithiasis were designated as the patients and the control group, respectively. A face-to-face survey was carried out using a food-frequency questionnaire. After adjustment for physical activity level and total energy intake, multivariate logistic regression models were applied to search for risk factors for urolithiasis.

Results

There were no significant differences between the two groups in gender, age, body mass index, family history, or total energy intake. The physical activity level of the control group was significantly higher than that of the patients (p=0.012). The results of the multivariate logistic regression model demonstrated that intake of carbohydrate (odds ratio [OR], 1.055; 95% confidence interval [CI], 1.012–1.099), protein (OR, 1.101; 95% CI, 1.001–1.211), and cereals (OR, 1.012; 95% CI, 1.002–1.023) could increase the risk for urolithiasis.

Conclusions

A higher intake of carbohydrate, protein, and cereal may increase the risk of urinary stone formation among Korean people.

Correlation of Osteoporosis and Calcium Urolithiasis in Adult Population

Introduction:

Scientific studies indicate that there is a correlation between decreased bone mineral density and the age of the patient, especially in post menopausal women.

Goal:

The aim of our study was to assess the connection between osteoporosis and the age of respondents, based on the DEXA findings in patients with calcium urolithiasis.

Material and methods:

The study was prospectively and conducted in University Clinical Center Banja Luka, at the Urology Clinic and Clinic of Internal Medicine. In this study the respondents were divided into two groups: experimental group–subjects with calcium urolithiasis and control group without calcium urolithiasis. The study included 240 patients, in both groups of 120 patients who were divided into three age groups: 20-40 years, 40-60 years and more than 60 years. In both groups of respondents was conducted determination of bone mineral density in L2-L4 vertebra lumbar spine and hip by DEXA method.

Results:

Observing the whole sample of the experimental group, according to age groups it can be noticed that DEXA results are at 72.5% normal, 27.5% below expected value, more in women within older subgroups, 20% show signs of osteopenia and osteoporosis in 7.5 %. Share of patients with osteoporosis is statistically different (p<0.05) only between sub-groups 20-40 years and over 60 years. Although appears absolute difference in the participation of patients with osteopenia by age groups, the differences are not statistically significant (p>0.05). The share of patients with normal DEXA values was significantly lower in the group over 60 years compared to the other two age groups (p<0.05). At age subgroups of the control group, the youngest group of respondents share with normal DEXA finding is 95% and among the oldest group (over 60 years) this share is much lower and is 60%, which represents a statistically significant difference, and confirms the relationship (p<0.01). Normal DEXA findings decreases with increasing years, the share of those who do not have normal findings is higher in the elderly population.

Conclusion:

Our study has just shown that in adult patients with calcium urolithiasis osteoporosis is more prevalent in older patients and more pronounced in patients with calcium urolithiasis in relation to the population without the same.

Evaluation of calcium and magnesium in scalp hair samples of population consuming different drinking water: risk of kidney stone

The objective of this study was to examine the relationship between calcium (Ca) and magnesium (Mg) in underground water (UGW), bottled mineral water (BMW), and domestic treated water (DTW) with related to risk of kidney stones. The water samples were collected from different areas of Sindh, Pakistan. The scalp hair samples of both genders, age ranged 30-60 years, consuming different types of water, have or have not kidney disorders, were selected. The Ca and Mg concentrations were determined in scalp hair of study subjects and water by flame atomic absorption spectroscopy. The Ca and Mg contents in different types of drinking water, UGW, DTW, and BMW, were found in the range of 79.1-466, 23.7-140, and 45-270 mg/L and 4.43-125, 5.23-39.6, and 7.16-51.3 mg/L, respectively. It was observed that Ca concentration in the scalp hair samples of kidney stone patients consuming different types of drinking water was found to be higher (2,895-4721 μg/g) while Mg level (84.3-101 μg/g) was lower as compare to referents subjects (2,490-2,730 μg/g for Ca, 107-128 μg/g for Mg) in both genders. The positive correlation was found between Ca and Mg levels in water with related to kidney stone formations in population, especially who consumed underground water. A relative risk and odd ratio were calculated; the relative risk had a strong positive association with incidence of kidney stone which depends on types of drinking water.

Impact of calcium intake and intestinal calcium absorption on kidney stones in older women: the study of osteoporotic fractures

PURPOSE

Intestinal calcium absorption is thought to have a critical role in nephrolithiasis. However, to our knowledge no study has directly assessed this association. Therefore, we explored the relationship among intestinal fractional calcium absorption, calcium intake and nephrolithiasis.

MATERIALS AND METHODS

The Study of Osteoporotic Fractures is a prospective cohort of 9,704 postmenopausal women recruited from population based listings in 1986 and followed for more than 20 years. Secondary analyses were performed of 7,982 women who reported their history of nephrolithiasis, of which 5,452 (68%) underwent an oral radioactive calcium assay (45Ca). The impact of dietary and supplemental calcium on intestinal fractional calcium absorption was evaluated, and factors independently associated with nephrolithiasis were determined.

RESULTS

Fractional calcium absorption decreased with increased calcium intake, with no difference between dietary and supplemental calcium. Fractional calcium absorption was higher in women with a nephrolithiasis history among all calcium intake groups. Increased dietary calcium intake reduced the likelihood of nephrolithiasis by 45% to 54% (p=0.03). Women with a history of nephrolithiasis were less likely to supplement calcium (p<0.001). In adjusted analyses women who supplemented calcium were 21% to 38% less likely to have a nephrolithiasis history (p=0.007) and there was a 24% increased risk of kidney stones for each 10% increase in fractional calcium absorption (p=0.008).

CONCLUSIONS

Fractional calcium absorption is higher in women with a history of nephrolithiasis. Higher intestinal fractional calcium absorption is associated with a greater risk of historical nephrolithiasis. Dietary and supplemental calcium decrease fractional calcium absorption, and may protect against nephrolithiasis.

Analysis of bone mineral density in urolithiasis patients

BACKGROUND

The association between hypercalciuria and bone mineral density (BMD) has been already recognized. The aim of the present study is to relate BMD to age and sex and to evaluate the calcium metabolism and hypercalciuria-defined dietary or non-dietary category in patients with urolithiasis.

METHODS

The BMI of the L2-L4 lumbar vertebrae was measured in 310 renal stone patients (191 men and 119 women). Percent age matched score (%AMS), which is the percent ratio of measured BMD to the mean BMD of age-matched control subjects, was utilized for the appraisal of BMD. Low BMD groups were defined by lower than 90% of %AMS.

RESULTS

Low BMD was observed in 27.7% of urinary stone patients, which was not a significant difference to that of control subjects (23.5%) who were measured in the health examination. In male patients with urolithiasis, the frequency of patients in whom BMD had been apt to decrease since youth was high, but there was not a proven significant difference among the three age groups (20-39 years old, 40-59 years old and 60 years old or older). In contrast, for female stone patients, the frequency of low BMD markedly increased in patients aged 40 years or older, when menopause occurs. Furthermore, in female stone patients with hypercalciuria, the frequency of reduced BMD reached more than 40%. When the cause was non-dietary hypercalciuria (classified mainly on the daily amount of urinary calcium excretion after ingestion of calculus test diet), the frequency of reduced BMD reached 65% (P < 0.01).

CONCLUSIONS

In case female stone patients with non-dietary hypercalciuria become menopausal, not only the risk of recurrent lithiasis increases, but the possibility of developing osteopenia in the future also increases. Appropriate treatments for prophylactic effects on urolithiasis or osteopenia should be considered, as judged from BMD, diet, sex, urinary calcium excretion and other factors synthetically.

ACP Best Practice No 181: Chemical pathology clinical investigation and management of nephrolithiasis

Renal stones have afflicted humans for millennia but there is still no solution to this problem. This review discusses the laboratory and metabolic aspects of the clinical management of patients with renal stones, both primary and secondary in origin. First, non-pharmacological interventions such as increased fluid intake, decreased protein consumption, dietary changes in sodium, calcium, oxalate, potassium, purine, vitamins, and essential fatty acids are considered. Then specific pharmacological treatment to modify urine calcium, oxalate, urate, citrate, and acidity are considered. Finally, more unusual types of stone are examined.

Determination of the Optimal Number of Dairy Servings to Ensure a Low Prevalence of Inadequate Calcium Intake in Americans

BACKGROUND

Many Americans are not getting the recommended amounts of calcium in their diet. Since dairy foods provide most of the calcium in the diet, the number of recommended servings of dairy products may need to be revised.

OBJECTIVE

1. To determine the calcium intake of various age groups that met or exceeded the intake of dairy products recommended by the Food Guide Pyramid (FGP). 2. To determine the optimal level of dairy consumption that ensures a low prevalence of inadequate calcium (Ca) intake by Americans.

METHODS

Using data from the Continuing Survey of Food Intake by Individuals, 1994-96, 1998, (CSFII) and the National Health and Nutrition Examination Survey, 1999-2000 (NHANES) we determined the calcium intake in individuals who met the recommended daily dairy servings as well as the minimum number of dairy servings required for the mean Ca intake of various age groups to exceed their respective Adequate Intakes (AI).

RESULTS

Objective 1: Meeting or exceeding the FGP dairy recommendation led to calcium intakes that met recommended levels. However, very few individuals in all age groups met or exceeded the number of dairy servings recommended by FGP. Objective 2: Results indicated that in children 2-8 yrs, 2 dairy servings/d were required for the mean Ca intake (835 +/- 72 and 822 +/- 68 mg/d, in CSFII and NHANES IV, respectively) to exceed the AI. In children 9-18 yrs, 4 dairy servings/d) were required for the mean Ca intake of the group (1540 +/- 93 and 1518 +/- 86 mg/d) to exceed the AI. Similar data were observed in adults 19+ yrs, e.g., in adults 51+ yrs, 3 dairy servings/d were required for the mean Ca intake of the group (1241 +/- 53 and 1217 +/- 53 mg/d) to exceed the AI.

CONCLUSION

Groups that met or exceeded the FGP dairy recommendations were more likely to have a mean calcium intake above the AI but had an average intake of about one serving higher than current recommendations. In individuals 9 yrs and older, 3-4 servings of dairy products are needed to meet or exceed the Ca AI and to ensure a low prevalence of inadequate Ca intake.

Calcium intake trends and health consequences from childhood through adulthood

Issues involving low calcium intake and dairy product consumption are currently the focus of much debate and discussion at both the scientific and lay community levels. In this review, we examine the following major areas of interest: (1). the role of calcium intake and dairy product consumption in chronic diseases, (2). nutritional qualities of milk and other dairy products, (3). trends in calcium intake and dairy product consumption, (4). current status of calcium intakes and dairy product consumption in children, (5). tracking of calcium intake and diary product consumption, (6). the impact of school meal participation on calcium intake and dairy product consumption, (7). concerns related to calcium-fortified foods and beverages and (8). factors influencing children's milk consumption. To date, the findings indicate that calcium intake and dairy product consumption have beneficial roles in a variety of chronic diseases; dairy products provide an abundant source of vitamins and minerals; calcium intakes of children have increased over time, yet intakes are not meeting the current adequate intake (AI) calcium recommendations; dairy consumption has decreased, and soft drink consumption and, possibly, consumption of calcium-fortified products have increased; consumption of dairy products have a positive nutritional impact on diets of children, particularly from school meals, and there are many factors which influence children's milk consumption, all of which need to be considered in our efforts to promote adequate calcium intakes by children. Based on this review, areas that need immediate attention and future research imperatives are summarized in an effort to further our understanding on what we already know and what we need to know to promote healthier eating habits early in life.

Dietary minerals and modification of cardiovascular risk factors

High serum cholesterol, hypertension and obesity are major risk factors for cardiovascular diseases, and together with insulin resistance form a deadly disorder referred to as the metabolic syndrome. All the aspects of this syndrome are strongly related to dietary and lifestyle factors; therefore, it would be reasonable to look for dietary approaches to their modification. Mineral nutrients, such as calcium, potassium and magnesium, lower blood pressure, and especially calcium has beneficial effects also on serum lipids. Recent evidence suggests that increased intake of calcium may help in weight control as well. This review summarizes previous literature on the effects and use of dietary minerals on serum lipids, blood pressure and obesity, with specific focus on the effects of calcium. Calcium and magnesium as divalent cations can form insoluble soaps with fatty acids in the intestine and thus prevent the absorption of part of the dietary fat. Decreased absorption of saturated fat leads to reduction in serum cholesterol level via decreased production of VLDL and increased intake of LDL in the liver. Dietary calcium may also bind bile acids, which increases the conversion of cholesterol to bile acids in the liver. Furthermore, calcium appears to enhance the cholesterol-lowering effect of plant sterols. Thus, dietary combination of the mineral nutrients and plant sterols provides a promising novel approach to the modification of cardiovascular risk factors.

Biomarkers of bone health appropriate for evaluating functional foods designed to reduce risk of osteoporosis

Osteoporosis is a growing global problem. The health care costs and decreased productivity and quality of life are staggering. Much research is invested in life-style approaches to build peak bone mass during growth to prevent osteoporosis as well as to treat the disease in later life. Functional foods have enjoyed a niche in bone health. Foods fortified with Ca are most popular. Other bone nutrients such as vitamin D, Mg and vitamin K are sometimes added. Future products are likely to include enhancers of Ca absorption such as inulin or whey proteins. Dietary factors that reduce urinary Ca loss (plant proteins) or suppress bone resorption (possibly phyto-oestrogens) are also gaining attention. Methodologies for evaluating the effectiveness of functional foods on bone health include measures of bone quality such as bone densitometry or measures of Ca metabolism, particularly absorption. Biochemical markers for bone turnover are less satisfactory for diet-related effects. Use of a rare isotope, 41Ca, and accelerator mass spectrometry offers a new approach for assessing the ability of functional foods to suppress bone resorption.

Effects of 5 different diets on urinary risk factors for calcium oxalate kidney stone formation: evidence of different renal handling mechanisms in different race groups

PURPOSE

Since the incidence of renal calculi in the South African black population is extremely rare while in white subjects it occurs at the same rate as elsewhere in the western world, we investigated the possibility that different renal handling mechanisms in response to different dietary challenges might occur in the 2 race groups.

MATERIALS AND METHODS

We administered 5 different dietary protocols, including low calcium, high oxalate, vitamin C, high salt and lacto-vegetarian, to 10 healthy male subjects from each race group. We collected 24-hour urine at baseline and after 4 days on the prescribed diet which were analyzed for biochemical and physicochemical risk factors. Dietary intake was controlled throughout the experimental period. A 24-hour dietary recall questionnaire was recorded at baseline and analyzed using food composition tables. Statistical analysis of variance was performed on all the data.

RESULTS

The low calcium diet caused statistically significant changes only in black subjects, which consisted of urinary oxalate increase (0.17 to 0.23 mmol./24 hours, p = 0.01), relative supersaturation of calcium oxalate decrease (1.88 to 0.97, p = 0.03) and relative supersaturation of brushite increase (0.85 to 1.69, p = 0.03). The high oxalate diet caused statistically significant changes in both race groups but these changes were different in the 2 groups. In white subjects urinary pH increased (6.24 to 6.62, p = 0.01), potassium excretion increased (40.01 to 73.49, p = 0.01) and relative supersaturation of brushite increased (1.34 to 2.12, p = 0.05). In black subjects urinary citrate increased (1.94 to 2.99 mmol./24 hours, p = 0.01). Clinically unimportant changes occurred in both race groups after the other 3 diets.

CONCLUSIONS

Renal handling of dietary calcium and oxalate in South African black and white subjects is different and may explain the different stone incidence in the 2 race groups.

The Importance of Meeting Calcium Needs with Foods

Calcium can be obtained from foods naturally rich in calcium such as dairy foods, from calcium-fortified foods and beverages, from supplements or from a combination of these. Recognition of calcium's many health benefits, along with Americans' low calcium intake, has led to interest in how best to meet calcium needs. Foods are the preferred source of calcium. Milk and other dairy foods are the major source of calcium in the U.S. In addition, these foods provide substantial amounts of other essential nutrients. Consequently, intake of dairy foods improves the overall nutritional quality of the diet. Other foods such as some green leafy vegetables, legumes and cereals provide calcium, but generally in lower amounts per serving than do dairy foods. Also, some components such as phytates in cereals and oxalates in spinach reduce the bioavailability of calcium. Calcium-fortified foods and calcium supplements are an option for individuals who cannot meet their calcium needs from foods naturally containing this mineral. However, their intake cannot correct poor dietary patterns of food selection which underlie Americans' low calcium intake. Considering the adverse health and economic effects of low calcium intakes, strategies are needed to optimize calcium intake. A first step is to recognize factors influencing dietary calcium consumption. Substituting soft drinks for milk and eating away from home are among the barriers to adequate calcium intake. The American public needs to understand why consuming foods containing calcium is the best way to meet calcium needs and learn how to accomplish this objective.

Prevention of nephrolithiasis

The high incidence of recurrence after an initial stone event underscores the need for an effective medical prophylactic program. Dietary modification and drug therapies have long been advocated to reduce the likelihood of stone recurrence. While the efficacy of a high fluid intake has been validated in a randomized trial, the benefit of other dietary measures is based on modulation of urinary stone risk factors and outcomes derived from observational studies. Several drug therapies have been evaluated in a limited number of prospective, randomized trials and efficacy has been demonstrated for thiazides, allopurinol and alkali citrate in some populations of recurrent stone formers. The role of selective versus nonselective therapy for stone prevention awaits further study.