Gastric acidity, atrophic gastritis, and calcium absorption

Recommended calcium intake in adults and children with chronic kidney disease-a European consensus statement

Mineral and bone disorders (MBD) are common in patients with chronic kidney disease (CKD), contributing to significant morbidity and mortality. For several decades, the first-line approach to controlling hyperparathyroidism in CKD was by exogenous calcium loading. Since the turn of the millennium, however, a growing awareness of vascular calcification risk has led to a paradigm shift in management and a move away from calcium-based phosphate binders. As a consequence, contemporary CKD patients may be at risk of a negative calcium balance, which, in turn, may compromise bone health, contributing to renal bone disease and increased fracture risk. A calcium intake below a certain threshold may be as problematic as a high intake, worsening the MBD syndrome of CKD, but is not addressed in current clinical practice guidelines. The CKD-MBD and European Renal Nutrition working groups of the European Renal Association (ERA), together with the CKD-MBD and Dialysis working groups of the European Society for Pediatric Nephrology (ESPN), developed key evidence points and clinical practice points on calcium management in children and adults with CKD across stages of disease. These were reviewed by a Delphi panel consisting of ERA and ESPN working groups members. The main clinical practice points include a suggested total calcium intake from diet and medications of 800-1000 mg/day and not exceeding 1500 mg/day to maintain a neutral calcium balance in adults with CKD. In children with CKD, total calcium intake should be kept within the age-appropriate normal range. These statements provide information and may assist in decision-making, but in the absence of high-level evidence must be carefully considered and adapted to individual patient needs.

Use of acid-suppressive drugs and risk of fracture in children and young adults: a meta-analysis of observational studies

BACKGROUND

Acid-suppressive drugs (ASDs) are being used by increasing number of children and young adults. However, evidence for a relationship between ASD use and the risk of fracture in these groups of patients is conflicting. We conducted a meta-analysis to evaluate the risk of fracture in children and young adults exposed to ASDs.

METHODS

A literature search was performed using the PUBMED, EMBASE, and Cochrane Library databases from inception to November 2020. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated to determine the relationship of ASD use with fracture risk in children and young adults.

RESULTS

Six studies reporting the outcomes of more than 900,000 children and young adults with ASD use were included in the meta-analysis. The pooled RR for fracture with the use of proton pump inhibitors (PPIs) versus non-use of these medications was 1.17 (95% CI = 1.1-1.25; P < 0.001) in children and 1.2 (95% CI = 0.87-1.65; P = 0.272) in young adults. By contrast, the use of histamine H2-receptor antagonists (H2RAs) was not significantly associated with fracture risk in children (RR, 1.08, 95% CI = 0.99-1.17; P = 0. 083) or young adults (RR, 1.08, 95% CI = 0.82-1.42; P = 0.589). Significant statistical and clinical heterogeneity among studies were determined for the main analysis and most of the subgroup analyses.

CONCLUSIONS

Our study provides evidence linking PPI use to an increased risk of fracture in children. Thus, the use of PPIs in these patients should be carefully considered. However, randomized controlled studies are needed to determine causality and the role of unmeasured/residual confounding factors in this association.

Intestinal Calcium Absorption

In this article, we focus on mammalian calcium absorption across the intestinal epithelium in normal physiology. Intestinal calcium transport is essential for supplying calcium for metabolism and bone mineralization. Dietary calcium is transported across the mucosal epithelia via saturable transcellular and nonsaturable paracellular pathways, both of which are under the regulation of 1,25-dihydroxyvitamin D₃ and several other endocrine and paracrine factors, such as parathyroid hormone, prolactin, 17β-estradiol, calcitonin, and fibroblast growth factor-23. Calcium absorption occurs in several segments of the small and large intestine with varying rates and capacities. Segmental heterogeneity also includes differential expression of calcium transporters/carriers (e.g., transient receptor potential cation channel and calbindin-D_9k ) and the presence of favorable factors (e.g., pH, luminal contents, and gut motility). Other proteins and transporters (e.g., plasma membrane vitamin D receptor and voltage-dependent calcium channels), as well as vesicular calcium transport that probably contributes to intestinal calcium absorption, are also discussed. © 2021 American Physiological Society. Compr Physiol 11:1-27, 2021.

Increased risk of osteoporosis in patients with peptic ulcer: a follow-up study using a national sample cohort

We performed a nationwide, population-based cohort study to investigate the risk of osteoporosis in patients with peptic ulcer disease in South Korea and concluded that peptic ulcer disease is associated with an increased risk of osteoporosis.

PURPOSE

This study aimed to evaluate the association between peptic ulcer disease (PUD) and the occurrence of osteoporosis using a national sample cohort from South Korea.

METHODS

Using the national cohort study from the Korean National Health Insurance Service, we extracted data for patients with PUD (n = 50,002) and for 1:1 matched control participants (n = 50,002); we then analyzed the occurrence of osteoporosis from 2002 to 2013. The patients were matched according to age, sex, income, region of residence, and past medical history. A stratified Cox proportional hazards model was used to analyze the hazard ratios (HRs) and the 95% confidence intervals (CIs). Subgroup analyses were performed based on age and sex.

RESULTS

The adjusted HR for osteoporosis was 1.36 (95% CI = 1.33-1.40, P < 0.001) in the PUD group. In the subgroup analysis based on age and sex, the respective adjusted HRs of PUD for osteoporosis were 1.33 (95% CI = 1.21-1.47) in the < 65-year-old group of men and 1.42 (95% CI = 1.30-1.56) in the ≥ 65-year-old group of men (each P < 0.001). The respective adjusted HRs of PUD for osteoporosis were 1.34 (95% CI = 1.29-1.39) in the < 65-year-old group of women and 1.38 (95% CI = 1.33-1.47) in the ≥ 65-year-old group of women (each P < 0.001).

CONCLUSION

In the current nationwide cohort study, we found that PUD is associated with an increased risk of osteoporosis regardless of sex.

Position of the Academy of Nutrition and Dietetics: Micronutrient Supplementation

It is the position of the Academy of Nutrition and Dietetics that micronutrient supplements are warranted when requirements are not being met through the diet alone. Those with increased requirements secondary to growth, chronic disease, medication use, malabsorption, pregnancy and lactation, and aging may be at particular risk for inadequate dietary intakes. However, the routine and indiscriminate use of micronutrient supplements for the prevention of chronic disease is not recommended, given the lack of available scientific evidence. A few specific age and disease states that may benefit from micronutrient supplementation are discussed. The most common dietary supplements used by both children and adults in the United States contain micronutrients. Consumers may not be well informed about the safety and use of these products, and some may have difficulty interpreting product labels. Thus, the expertise of registered dietitian nutritionists and nutrition and dietetic technicians, registered, is needed to guide the safe and appropriate selection and use of micronutrient supplements. To accomplish this, registered dietitian nutritionists and nutrition and dietetic technicians, registered, must keep up to date on efficacy, safety, and the regulatory issues influencing the use of these products. This position paper aims to increase awareness of current issues relevant to micronutrient supplementation and of the resources available to assist registered dietitian nutritionists and nutrition and dietetic technicians, registered, in evaluating their potential benefits and adverse outcomes.

Advantages and Disadvantages of Long-term Proton Pump Inhibitor Use

Proton pump inhibitors (PPIs) potently inhibit gastric acid secretion and are widely used for treatment of acid-related diseases including gastroesophageal reflux disease and secondary prevention of aspirin/NSAID-induced ulcers. Although clinically important adverse effects of PPIs can occur, just as with other drugs, those are not frequently observed during or after administration. Thus, PPIs are regarded as relatively safe and considered to be clinically beneficial. Recently, PPIs have become frequently administered to patients with functional gastrointestinal diseases or primary prevention of drug-related gastroduodenal damage, even though their beneficial effects for those conditions have not been fully confirmed. PPIs tend to be given for conditions in which the necessity of the drug has not been clarified, thus otherwise rare adverse effects are presented as clinically relevant. Although several PPI-related adverse effects have been reported, their clinical relevance is not yet clear, since the evidence reported in those studies is not at a high enough level, as the majority are based on retrospective observational studies and the reported hazard ratios are low. It is important to administer PPIs only for patients who will gain a substantial clinical benefit and to continue to investigate their adverse effects with high quality prospective studies.

The influence of dietary fat and intestinal pH on calcium bioaccessibility: anin vitrostudy

In vivostudies measuring true fractional calcium (Ca) absorption have shown that dietary fat is a significant predictor of absorption and is influenced by luminal pH levels.

Long non-coding RNA polymorphisms in 6p21.1 are associated with atrophic gastritis risk and gastric cancer prognosis

It has been suggested that the genetic variation in human chromosome 6p21.1 has potential importance for the susceptibility to gastric cancer (GC). The study aims to explore the relationship between the long non-coding RNA (lncRNA) polymorphisms in 6p21.1 and the risk of GC as well as atrophic gastritis (AG). Genotyping for eight single nucleotide polymorphisms (SNPs) was conducted using Sequenom MassARRAY platform in a total of 2507 northern Chinese subjects, including 749 GC cases, 878 AG cases and 880 controls. The results showed rs61516247 was associated with an increased AG risk in overall population (AA vs. GG: P = 0.046, OR = 1.46; A vs. G: P = 0.037, OR = 1.18). Four SNPs, rs61516247, rs1886753, rs7747696 and rs7749023 were associated with AG risk in some specific subgroups. Among them, rs1886753 had an interaction effect with H.pylori infection on AG risk (P_interaction = 0.038, OR = 1.62). In prognosis analysis, two SNPs, rs80112640 (AG+GG vs. AA: P = 0.047, HR = 0.56; G vs. A: P = 0.039, HR = 0.57) and rs72855279 (P = 0.043, HR = 0.57) were found to improve the overall survival of GC patients. In conclusion, lncRNA SNPs in 6p21.1 are associated with AG risk and GC prognosis. Our study provides all-new research clues for screening lncRNA-based biomarkers in the cancer-related hotspot region 6p21.1 with the potential to predict risk and prognosis of GC along with its precursor.

Effects of dietary acidifiers on growth, hematology, immune response and disease resistance of Nile tilapia, Oreochromis niloticus

Organic acids or their salts can be used as feed additives in aquaculture. This study was conducted to evaluate the use of a mixture of formic acid, propionic acid and calcium propionate compared with oxytetracycline (OTC). A total of 720 apparently healthy Oreochromis niloticus fingerlings with an average body weight of 28.8 ± 0.14 g (mean ± SE) were randomly divided into four equal groups (G1, G2, G3and G4). G1 was fed a basal diet with no additive as the control group, while G2 and G3 were fed a formic and propionic acid/salt mixture in 1 and 2 g/kg, respectively. G4 was fed OTC (0.5 g/kg). Each group was subdivided into tow subgroups A and B (30 fish/subgroup) in triplicate. The first subgroup was used to evaluate growth performance, hematology and body composition for 60 d. The second subgroup was used to examine immunity, gut microbiota and resistance to infection for 30 d. At the end of the feeding period (60 d), G3 had significant improvements in final body weight (FBW), weight gain (WG), specific growth rate (SGR) and food conversion ratio (FCR) compared with other groups. The total erythrocyte count, hemoglobin content, platelet count, hematocrit, mean corpuscular hemoglobin and total leukocyte count were significantly increased in G3 and G2 compared with G1 and G4. Mean corpuscular volum, lymphocyte and neutrophil percentages had the highest significant improvement in G3. There were no significant differences among the groups in mean corpuscular hemoglobin concentration and monocyte percentage. The protein and fat contents of the whole body were the highest in G3. The widest inhibition zones against Aeromonas sobria were at the 30, 40 and 50% concentrations of acidifiers, which were equivalent to OTC (30 μg). G3 showed the lowest total gastrointestinal bacterial counts, followed by G2. After 15 and 30 d, G3 had the highest serum killing, lysozyme and nitric oxide activities. Serum lysozyme activity and nitric oxide assay had no significant difference between G1 and G2 after 30 d. The lowest immune parameters were recorded in G4. After 30 d, the highest expression of interleukin-1β and tumor necrosis factor-alpha in the liver and kidney were found in G3. The best protection against challenged Aeromonas sobria was in G3, followed by G2 and G4. Dietary supplementation with a combination of formic acid, propionic acid and calcium propionate improves the performance of Nile tilapia.

Digestion and Postprandial Metabolism in the Elderly

The elderly are an increasing segment of the population. Despite the rapid gains in medical knowledge and treatments, older adults are more likely to experience chronic illnesses that decrease quality of life and accelerate mortality. Nutrition is a key modifiable lifestyle factor which greatly impacts chronic disease risk. Yet despite the importance of nutrition, relatively little is known of the impact of advancing age on the gastrointestinal function, the digestive responses, and the post-meal metabolic adaptations that occur in response to ingested food. Knowledge of the age-related differences in digestion and metabolism in the elderly is essential to the development of appropriate nutritional recommendations for the maintenance of optimal health and prevention of disease.

Osteoporosis in the at-risk asthmatic

The effect of inhaled glucocorticosteroids (ICS) on bone metabolism and subsequent osteoporosis is controversial. Explanations for this controversy include various study designs, duration of use, outcome measures, and population demographics of research studies with intranasal or inhalational ICS. Patients with poorly controlled asthma are at greatest risk of osteoporosis because they are commonly treated with intermittent or continuous systemic corticosteroids (SCS) or high-dose ICS. A 45-year-old Caucasian woman presents with moderate-to-severe asthma with frequent albuterol use and nighttime awakenings at least once weekly. She is on fluticasone/salmeterol 500/50 μg one inhalation twice daily and montelukast 10 mg/day. She requires prednisone 15 mg three times per day for 5 days up to three times a year. Is this patient at greater risk of osteopenia, characterized by a T-score between -1.0 and -2.5, and subsequent osteoporosis and an increased risk of fractures? If she has osteopenia, should she be treated with a bisphosphonate? The risk of osteoporosis and fracture increases significantly with frequent administration of SCS, and patients on such medications should undergo preventative measures and treatment. This study discuses factors that contribute to an increased risk of osteoporosis/osteopenia in patients with asthma and suggests recommendations based on the current literature.

Risk of fracture and pneumonia from acid suppressive drugs

A recently published systematic review and meta-analysis, incorporating all relevant studies on the association of acid suppressive medications and pneumonia identified up to August 2009, revealed that for every 200 patients, treated with acid suppressive medication, one will develop pneumonia. They showed the overall risk of pneumonia was higher among people using proton pump inhibitors (PPIs) [adjusted odds ratio (OR) = 1.27, 95% CI: 1.11-1.46, I² = 90.5%] and Histamine_-2 receptor antagonists (H₂RAs) (adjusted OR = 1.22, 95% CI: 1.09-1.36, I² = 0.0%). In the randomized controlled trials, use of H₂RAs was associated with an elevated risk of hospital-acquired pneumonia (relative risk 1.22, 95% CI: 1.01-1.48, I² = 30.6%). Another meta-analysis of 11 studies published between 1997 and 2011 found that PPIs, which reduce stomach acid production, were associated with increased risk of fracture. The pooled OR for fracture was 1.29 (95% CI: 1.18-1.41) with use of PPIs and 1.10 (95% CI: 0.99-1.23) with use of H₂RAs, when compared with non-use of the respective medications. Long-term use of PPIs increased the risk of any fracture (adjusted OR = 1.30, 95% CI: 1.15-1.48) and of hip fracture risk (adjusted OR = 1.34, 95% CI: 1.09-1.66), whereas long-term H₂RA use was not significantly associated with fracture risk. Clinicians should carefully consider when deciding to prescribe acid-suppressive drugs, especially for patients who are already at risk for pneumonia and fracture. Since it is unnecessary to achieve an achlorhydric state in order to resolve symptoms, we recommend using the only minimum effective dose of drug required to achieve the desired therapeutic goals.

Use of acid-suppressive drugs and risk of fracture: a meta-analysis of observational studies

PURPOSE

Previous studies have reported inconsistent findings regarding the association between the use of acid-suppressive drugs such as proton pump inhibitors (PPIs) and histamine 2 receptor antagonists (H(2)RAs) and fracture risk. We investigated this association using meta-analysis.

METHODS

We searched MEDLINE (PubMed), EMBASE, and the Cochrane Library from inception through December 2010 using common key words. We included case-control, nested case-control, and cohort studies. Two evaluators independently reviewed and selected articles. We determined pooled effect estimates by using random-effects meta-analysis, because of heterogeneity.

RESULTS

Of 1,809 articles meeting our initial inclusion criteria, 5 case-control studies, 3 nested case-control studies, and 3 cohort studies were included in the final analyses. The pooled odds ratio (OR) for fracture was 1.29 (95% confidence interval [CI], 1.18-1.41) with use of PPIs and 1.10 (95% CI, 0.99-1.23) with use of H(2)RAs when compared with nonuse of the respective medications. Long-term use of PPIs increased the risk of any fracture (adjusted OR = 1.30; 95% CI, 1.15-1.48) and hip fracture risk (adjusted OR = 1.34; 95% CI, 1.09-1.66), whereas long-term H(2)RA use was not significantly associated with fracture risk.

CONCLUSIONS

We found possible evidence linking PPI use to an increased risk of fracture, but no association between H(2)RA use and fracture risk. Widespread use of PPIs with the potential risk of fracture is of great importance to public health. Clinicians should carefully consider their decision to prescribe PPIs for patients already having an elevated risk of fracture because of age or other factors.

Proton pump inhibitors and fracture risk: true effect or residual confounding?

Fracture is a major contributor to human morbidity and mortality, especially in the elderly. It has been discussed in the literature that conditions associated with decreased stomach acidity may lead to a decrease in intestinal calcium absorption and, consequently, to an increased fracture risk. In recent years, several observational studies reported a slightly increased fracture risk in association with the use of proton pump inhibitors (PPIs) and/or histamine H(2) receptor antagonists. It was the objective of this review to critically assess the available evidence linking PPI use to an increased fracture risk. A MEDLINE and EMBASE search from 1960 to June 2010 was performed to identify the relevant articles using predefined search terms. Because (i) there is no proven mechanism, (ii) the reported magnitude of the risk elevation associated with the use of PPIs was only weak, and (iii) the likelihood of residual confounding despite adjustment for known co-morbidities and drug use cannot be ruled out, we conclude that the currently available literature does not support the notion that the use of PPIs is causally related to a materially increased fracture risk in humans.

High-Calcium Milk Prevents Overweight and Obesity among Postmenopausal Women

Background

The Sixth National Nutrition Survey 2003 revealed that the highest prevalence of overweight and obesity among Filipino female adults (30.8%) was found in the age group from 40 to 59 years. Obesity is associated with a number of chronic diseases, including cardiovascular disease, hypertension, and diabetes. Low calcium intake has been identified as a potential contributing factor to overweight and obesity.

Objective

To assess the effect of a high-calcium, fortified, low-fat milk drink with added vitamin D versus a low-calcium placebo drink on anthropometric measurements of postmenopausal women.

Methods

Women who were at least 5 years postmenopausal were invited to participate in the study. Potential participants underwent three stages of screening: initial interview, dual-energy x-ray absorptiometry, and blood testing for biochemical screening. Anthropometric indices were measured at baseline and the end of the study. Sixty women were qualified to participate in the study. The women were randomly assigned to two groups, one of which received 400 ml of the high-calcium milk daily for 16 weeks while the other received the placebo drink.

Results

No significant increases were observed in the anthropometric indices of the subjects receiving the high-calcium fortified milk at the end of the study. However, there were significant increases in the weight ( p = .008), body mass index ( p = .007), and waist ( p = .018) and hip ( p = .003) circumferences of the subjects receiving the placebo drink.

Conclusions

A change in dietary calcium intake may be a useful measure as part of an overall approach to prevent the occurrence of overweight and obesity among postmenopausal women.

Activation of the calcium sensing receptor stimulates gastrin and gastric acid secretion in healthy participants

In 17 adults on a fixed metabolic diet, an 11-day course of cinacalcet increased serum gastrin and basal gastric acid output, but not maximal gastric acid output, compared with a placebo. These findings indicate that the calcium sensor receptor plays a role in the regulation of gastric acid.

INTRODUCTION

Gastric acid secretion is a complex process regulated by neuronal and hormonal pathways. Ex vivo studies in human gastric tissues indicate that the calcium sensing receptor (CaR), expressed on the surface of G and parietal cells, may be involved in this regulation. We sought to determine whether cinacalcet, a CaR allosteric agonist, increases serum gastrin and gastric acid secretion.

METHODS

Seventeen healthy adults with normal gastric acid output were placed on an 18-day metabolic diet. On day 8 (baseline), participants were given cinacalcet (15 then 30 mg/day) or placebo for 11 days. Changes in gastric acid output, serum gastrin, and other measures were compared in the two groups.

RESULTS

Changes in serum gastrin and basal acid output (adjusted for baseline body weight) were significantly more positive in the cinacalcet group compared with placebo (P = 0.004 and P = 0.039 respectively). Change in maximal acid output was similar in the two groups (P = 0.995). As expected, cinacalcet produced significant decreases in serum PTH (P < 0.001) and ionized calcium levels (P = 0.032), and increases in serum phosphorus levels (P = 0.001) and urinary calcium (P = 0.023).

CONCLUSIONS

This study provides in vivo evidence that activation of the CaR increases serum gastrin levels and basal gastric acid secretion in healthy adults.

The clinical significance of gastrointestinal changes with aging

PURPOSE OF REVIEW

With the graying of the world's population, there is an increased interest in the physiological effects of aging. This review examines the physiological changes of the gut with aging and their clinical significance.

RECENT FINDINGS

Changes with aging in the gastrointestinal tract are variable, but in some cases they are responsible for a variety of symptoms. Thus, alterations in taste and smell, gastric motility, intestinal overgrowth and changes in gastrointestinal hormone release are the basis of the physiological anorexia of aging. Alterations in swallowing lead to silent aspiration. Changes in gastric emptying play a role in postprandial hypotension. Changes in gastrointestinal function can lead to constipation and fecal incontinence. Weakening of the colonic muscular wall produces diverticula. Achlorhydria is associated with malabsorption of some forms of iron and calcium. Vitamin D malabsorption aggravates the hypovitaminosis D that is so common in older persons. Changes in probiotics can lead to diarrhea and altered immune system. In the liver, aging is associated with delayed drug metabolism.

SUMMARY

Changes in the physiology of the gut play a role in the anorexia of aging, aspiration pneumonia, postprandial hypotension, constipation and fecal incontinence.

Biodisponibilidade do cálcio dietético

O cálcio (Ca) dietético é fundamental para a saúde óssea. Tanto o teor como a biodisponibilidade do elemento nos alimentos devem ser considerados. Este artigo objetiva sumarizar os fatores envolvidos na absorção e destacar os alimentos com melhor disponibilidade do Ca. Este é absorvido principalmente no jejuno e o pH baixo parece favorecer sua absorção, que é maior no crescimento, na gestação/lactação e na carência de Ca ou fósforo (P), e menor no envelhecimento. As maiores fontes, e com melhor absorção, são os laticínios bovinos. Outros alimentos apresentam concentrações elevadas de Ca, mas com biodisponibilidade variável: os ricos em ácidos oxálico e fítico apresentariam uma menor absorção, enquanto que os ricos em carboidratos teriam uma absorção maior. Por apresentarem uma biodisponibilidade do Ca mais próxima da do leite bovino, o leite de outros animais, o de soja enriquecido e alguns vegetais, em quantidades adequadas, poderiam ser usados como alternativas a este.

Strategies for the Prevention and Treatment of Osteoporosis in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic disease that affects millions of patients worldwide. As better therapies emerge for treatment of this condition, patients with RA are living longer and are more likely to experience diseases associated with aging such as osteoporosis. The aetiology of osteoporosis in patients with RA is multifactorial, with some bone loss attributable to the underlying inflammatory disease. Patients may also experience bone loss that is a consequence of therapy with corticosteroids. Progress in the diagnosis and evaluation of osteoporosis has led to a greater awareness of this major health problem. There have also been many advances in our understanding of the pathophysiology of RA. However, recent studies have suggested that, despite our growing understanding of these diseases, therapies for preventing bone loss in this patient population are underutilised. Patients with RA, especially those taking corticosteroids or with persistent disease activity, must have their bone mass assessed with bone mineral density testing. RA patients with documented osteoporosis or those at high risk for the development of this potentially devastating complication should receive calcium and vitamin D supplementation as well as an anti-resorptive agent.

Relative bioavailability of calcium-rich dietary sources in the elderly

BACKGROUND

The recent increase in the dietary calcium recommendation from 800 to 1200 mg/d for persons aged > 51 y has made it important to identify alternative high-calcium dietary sources that the elderly can use in meeting their calcium requirement.

OBJECTIVE

We determined the bioavailability of calcium from 3 different sources: orange juice fortified with calcium-citrate malate, skim milk, and a calcium carbonate supplement.

DESIGN

Twelve subjects [9 women and 3 men with a mean (+/- SEM) age of 70 +/- 3 and 76 +/- 6 y, respectively] consumed low-calcium (300 mg/d) and high-calcium (1300 mg/d) diets for three 1-wk periods each during a 6-wk crossover study. The acute biochemical response to calcium from each of the 3 sources was assessed during a 4-h period after the initial breakfast meal of the high-calcium diet.

RESULTS

Postprandial suppression of serum parathyroid hormone did not differ significantly between the test meals containing calcium-fortified orange juice, the calcium carbonate supplement, and milk. This finding suggests that the calcium bioavailability from the 3 sources was equivalent. During the 1-wk high-calcium diet periods, fasting serum calcium increased by 3% (P < 0.0001), serum 1,25-dihydroxyvitamin D decreased by 20% (P < 0.0001), and a biomarker of bone resorption (serum N-telopeptide collagen cross-links) decreased by 14% (P < 0.02) compared with the low-calcium diet period. However, no differences among the supplemental calcium sources were found in these calcium-responsive measures or fasting serum parathyroid hormone concentration.

CONCLUSIONS

In elderly subjects, the calcium bioavailability of the 3 high-calcium dietary sources tested was equivalent, during both the acute postprandial and longer-term periods.

Role of Ca(2+) and vitamin D in the prevention and treatment of osteoporosis

Osteoporosis is defined as a progressive systemic skeletal disease characterised by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. The clinical relevance of osteoporosis derives from the fractures that it produces. More than one-third of the adult women will suffer one or more osteoporotic fractures in their lifetime. The lifetime risk in men is approximately one-half that in women. The decrease of the bone mineral density is the most important cause of risk fracture. Among other factors, Ca(2+) and vitamin D deficiencies are important risk factors for a decrease in bone mineral density, consequently inducing osteoporosis. The high prevalence of vitamin D deficiency in healthy elderly people living mainly in southern European countries increase the risk of osteoporotic fractures in these populations above those anticipated for the general elderly population of the European community. In addition, the ageing of the European population will double the number of osteoporotic fractures over the next 50 years, unless adequate preventative measures are undertaken. The efficacy and safety of Ca(2+) and vitamin D supplements at preventing bone loss and reducing the risk of hip and other fractures have been assessed in different clinical trials, which are extensively discussed in this review.

Human adult-onset lactase decline: an update

Human adult-onset lactase decline is a biologic feature characteristic of the maturing intestine in the majority of the world's population. The digestion and absorption of lactose, the major carbohydrate in milk and also the main substrate for lactase, is often variable, a consequence of lactase levels, gastric emptying rate, and colonic salvage. Although commercially available "lactase" products alleviate symptoms in many lactose-intolerant people, a greater understanding of this variability in lactose tolerance could lead to interventions that reduce the rate of gastric emptying and/or increase the proliferation of lactose-metabolizing bacteria in the colon, leading to more efficient lactose utilization. Adult-onset lactase decline appears to be a risk factor for developing osteoporosis, owing to avoidance of dairy products or interference of undigested lactose with calcium absorption. Elderly with both adult-onset lactase decline and atrophic gastritis or those undergoing anti-ulcer treatment may have an increased risk of low calcium absorption owing to the lack of gastric acid that facilitates calcium uptake. Thus, lactose-intolerant elders should monitor their calcium nutrition status carefully.

Serum concentration and dietary intake of Mg and Ca in institutionalized elderly people

We determined the serum levels and the dietary intake of Mg and Ca in 93 institutionalized elderly people (24 men and 69 women) in Granada (Spain). The serum samples had mean concentrations of 21.39 +/- 2.08 mg/l magnesium and 93.39 +/- 9.24 mg/l calcium. No significant differences were found in the serum levels of the two minerals as regards the sex of the subjects. Application of linear regression analysis to the serum Mg and Ca levels showed a statistically significant positive correlation (P < 0.05). A low vitamin D intake of these subjects (51.8% of the recommended dietary allowance) was observed. The intakes of Ca and Mg correlated positively together, as well as with the intakes of energy, protein, fibre (in the case of Mg only), iron and phosphorus (P < 0.05). The Ca and energy intake were adequate to their current recommendations, as too was the Ca:P ratio, whereas the diet had a poor supply of fibre, vitamin D and Mg.

Adverse effects of high-calcium diets in humans

While the National Institutes of Health Consensus Conference on Calcium has recommended that all elderly persons need calcium intakes of 1500 mg/day, it also recognizes that adverse effects of high-calcium diets may occur at intakes greater than 2000 mg/day. The purpose of this paper is to highlight adverse effects of high-calcium diets that could have a negative impact on health.

Mineral bioavailability and bone mineral contents in pigs given calcium carbonate postprandially

We have further investigated the "meal effect" on mineral bioavailability in pigs by mineral balance studies and measurements of bone ash contents and bending moment. A group of seven pigs (CAA) was given all its dietary Ca as CaCO3 5 h after the first daily meal for 8 weeks. The control group of seven pigs received CaCO3 in the meal. Both groups were given normal P within the meals. Ca and P absorption and retention were evaluated by a 10-day balance trial. Several bones were collected at slaughter to determine bone ash, Ca, and P contents and bending moment (three-point bending test). Ingesting Ca after the meal did not affect Ca bioavailability or phosphorus absorption, but did reduce P retention, which in turn decreased the bone scores. Osteopenia, indicated by decreased total mineral contents of bones (and decreased ash:bone volume ratio), was associated with elevated plasma osteocalcin in the CAA group. Thus, CaCO3 need not be incorporated into a meal for high Ca absorption, provided that Ca is given after a meal, but simultaneous intakes of Ca and P are required for the best mineral retention.

Hypochlorhydria from short-term omeprazole treatment does not inhibit intestinal absorption of calcium, phosphorus, magnesium or zinc from food in humans

OBJECTIVE

Low gastric pH is generally believed to be an important factor in intestinal mineral absorption. Thus, hypochlorhydria could be an important risk factor for mineral malabsorption and the development of marginal mineral status. We studied whether the hypochlorhydria associated with treatment with the anti-ulcer medication omeprazole, a potent gastric proton pump inhibition, would affect intestinal calcium, phosphorus, magnesium, or zinc absorption from food.

METHODS

Thirteen normal, healthy adults were assigned to either a control group (n = 5) receiving no drug treatment or an omeprazole treatment group (n = 8) to produce increased gastric pH. Omeprazole treatment of normal volunteers resulted in a significant change in postprandial gastric pH (pH 6.4 +/- 0.3 vs. 3.6 +/- 0.5 in control subjects, p < 0.01) and baseline fasting pH (pH 5.8 +/- 0.5 vs. pH 1.8 +/- 0.3 in controls, p < 0.01) after an overnight fast. Net mineral absorption from a standard test meal was measured using a whole gut lavage technique. Mineral absorption was measured twice in each subject, once with 120 mL of 0.1 mol/liter hydrochloric acid and a second time with 120 mL of distilled water alone.

RESULTS

We found that despite marked changes in gastric pH due to drug treatment or administration of exogenous HCl, no change in the intestinal absorption of calcium, phosphorus, magnesium or zinc from a standard test meal was evident.

CONCLUSIONS

These findings suggest that changing the gastric pH alone does not modify the net intestinal absorption of several minerals from food. Therefore, it is unlikely that moderate hypochlorhydria resulting from short-term omeprazole treatment substantially increases the risk for developing calcium, phosphorus, magnesium, or zinc deficiencies due to mineral malabsorption.

Meal-feeding and phosphorus ingestion influence calcium bioavailability evaluated by calcium balance and bone breaking strength in pigs

The 'meal effect' on mineral bioavailability is evaluated in short-term studies on humans whereas feeding experiments on pigs lasting several weeks allow both mineral balance studies and measurements of bone ash contents or breaking strength. Three groups of 7 pigs were given 3 dietary treatments, differing essentially in the mode of Ca and P distribution, for 7 weeks. Group 1 received Ca and P within the meals, Group 2 was fed Ca separate from meals, and Group 3 was given both Ca and P separate from meals. Ca and P absorption were evaluated by a 10-day balance trial, then several bones were collected to determine mineral contents and breaking strength. Ca was much better absorbed and retained by giving CaCO3 within meals. Simultaneous administration of Ca and P did not influence Ca absorption, but tended to improve Ca and P retention. The best bone scores were obtained when CaCO3 and NaH2PO4 were given simultaneously in meals. The Ca and P balance values and bone parameters were strongly correlated. Thus meal incorporation and simultaneous intake of Ca and P are both required for the best mineral retention, evaluated by balance or bone scores.