Habitual high phosphorus intakes and foods with phosphate additives negatively affect serum parathyroid hormone concentration: a cross-sectional study on healthy premenopausal women

Phosphorous intake in foods and phosphorus status markers in circulation in the Boston Puerto Rican Health Study

Phosphorus (P) additives may be deleterious for health. We measured the P content of key foods, and associations of P intake with biomarkers in the Boston Puerto Rican Health Study (BPRHS). Direct chemical analysis of 92 foods was done with the molybdenum blue spectrophotometric method and inductively coupled plasma mass spectrometry (ICP-MS). A novel algorithm was used to determine bioavailable, natural, and added P. We estimated P intakes from foods in 1323 participants, aged 45-75 y, and associations of these with serum P, fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and Klotho. Relationships between intakes and status markers were assessed with Pearson's correlations and t-tests. Our food analyses generally support P values in the USDA nutrient database, with the exceptions of American and cheddar cheese, which had more P than in the database. Women had higher added P intake than men, and younger participants had higher added P than those older. Total P intake tended to be positively associated with serum P and klotho, and inversely associated with PTH, but relationships were not strong. Puerto Rican adults have high intake of additive P. Culturally sensitive interventions that highlight dietary quality are needed.

Determination of phosphate in food based on molybdenum yellow derivatization coupled with resonance Rayleigh scattering method

This paper proposed a rapid, selective and sensitive molybdenum yellow derivatization coupled with Resonance Rayleigh scattering (MYD-RRS) method for detection of phosphate. Under the acidic condition, phosphate can be selectively transformed to Keggin type of phosphomolybdic acid (PMA, i.e., PMo12O403-) through molybdenum yellow derivatization reaction prior to RRS detection. The PMA can further react with cationic methyl violet (MV) to form larger PMA-MV ion association complexes, generating significant RRS signal. The concentration of phosphate was linearly related to the RRS signal in the range of 8-200 ng/mL, with the determining coefficient (R2) of 0.9973 and the detection limit of 4 ng/mL. The analytical procedure can be completed within 10 min and the RRS signal intensity can remain stable more than 4 h. The method showed good stability toward temperature and time, and good anti-interference capability. The method was applied to the determination of phosphate in real food samples with the recovery of 85-117% and RSD of 1-5.2%. With the advantages of rapidness, high sensitivity and good selectivity, the MYD-RRS method exhibits great potential to the determination of phosphate in food. It also provides an instructive strategy for detection of analytes with weak RRS signal.

Female Athlete Triad and Relative Energy Deficiency in Sport (REDs): Nutritional Management

The female athlete triad (TRIAD) is a spectrum of disorders involving low energy availability (LEA), low bone mineral density, and menstrual disorders. It is increasingly common to use the term 'relative energy deficiency in sport' (RED), emphasising the extensive impact of LEA on the body. The aim of this narrative review was to gather original research encompassing female athletes across various sports as well as to collect findings on the potential of a nutrition-focused approach to prevent or treat the aforementioned disorders. A comprehensive search was conducted in PubMed and Scopus. Several challenges were identified regarding the adequacy of the energy availability, protein, and carbohydrate requirements in the diets of female athletes. Moreover, insufficient intake of vitamin D has been observed across all athlete groups studied. This insufficiency also extends to the average requirement for Ca, Mg, the Ca/P ratio, Zn, and Fe. To address those concerns, a nutritional approach is proposed in the latter part of this review. The factors that can improve the absorption of micronutrients have also been discussed. The TRIAD/REDs affect an ever-growing number of women and require appropriate therapeutic management, particularly through nutritional care. Therefore, cooperation within an interdisciplinary team comprising a physician, nutritionist, physiotherapist, and psychologist is crucial.

Mineral Supplements in Ageing

With advancing age, achievement of dietary adequacy for all nutrients is increasingly difficult and this is particularly so for minerals. Various factors impede mineral acquisition and absorption including reduced appetite, depressed gastric acid production and dysregulation across a range of signalling pathways in the intestinal mucosa. Minerals are required in sufficient levels since they are critical for the proper functioning of metabolic processes in cells and tissues, including energy metabolism, DNA and protein synthesis, immune function, mobility, and skeletal integrity. When uptake is diminished or loss exceeds absorption, alternative approaches are required to enable individuals to maintain adequate mineral levels. Currently, supplementation has been used effectively in populations for the restoration of levels of some minerals like iron, zinc, and calcium, but these may not be without inherent challenges. Therefore, in this chapter we review the current understanding around the effectiveness of mineral supplementation for the minerals most clinically relevant for the elderly.

Industrial Use of Phosphate Food Additives: A Mechanism Linking Ultra-Processed Food Intake to Cardiorenal Disease Risk?

The consumption of ultra-processed food (UPF) keeps rising, and at the same time, an increasing number of epidemiological studies are linking high rates of consumption of UPF with serious health outcomes, such as cardiovascular disease, in the general population. Many potential mechanisms, either in isolation or in combination, can explain the negative effects of UPF. In this review, we have addressed the potential role of inorganic phosphate additives, commonly added to a wide variety of foods, as factors contributing to the negative effects of UPF on cardiorenal disease. Inorganic phosphates are rapidly and efficiently absorbed, and elevated serum phosphate can lead to negative cardiorenal effects, either directly through tissue/vessel calcification or indirectly through the release of mineral-regulating hormones, parathyroid hormone, and fibroblast growth factor-23. An association between serum phosphate and cardiovascular and bone disease among patients with chronic kidney disease is well-accepted by nephrologists. Epidemiological studies have demonstrated an association between serum phosphate and dietary phosphate intake and mortality, even in the general American population. The magnitude of the role of inorganic phosphate additives in these associations remains to be determined, and the initial step should be to determine precise estimates of population exposure to inorganic phosphate additives in the food supply.

Understudied Hyperphosphatemia (Chronic Kidney Disease) Treatment Targets and New Biological Approaches

Hyperphosphatemia is a secondary disorder of chronic kidney disease that causes vascular calcifications and bone-mineral disorders. As per the US Centers for Disease Control and Prevention, renal damage requires first-priority medical attention for patients with COVID-19; according to a Johns Hopkins Medicine report, SARS-CoV-2 can cause renal damage. Therefore, addressing the research inputs required to manage hyperphosphatemia is currently in great demand. This review highlights research inputs, such as defects in the diagnosis of hyperphosphatemia, flaws in understanding the mechanisms associated with understudied tertiary toxicities, less cited adverse effects of phosphate binders that question their use in the market, socioeconomic challenges of renal treatment and public awareness regarding the management of a phosphate-controlled diet, novel biological approaches (synbiotics) to prevent hyperphosphatemia as safer strategies with potential additional health benefits, and future functional food formulations to enhance the quality of life. We have not only introduced our contributions to emphasise the hidden aspects and research gaps in comprehending hyperphosphatemia but also suggested new research areas to strengthen approaches to prevent hyperphosphatemia in the near future.

Long-Term Cola Intake Does Not Cause Evident Pathological Alterations in the Femoral Bone Microstructure: An Animal Study in Adult Mice

Short-term animal experiments and association studies in humans have shown that cola intake may have a detrimental impact on bone mineral density (BMD); however, other bone parameters have not been investigated. This study examined the effects of long-term cola consumption on the femoral bone microstructure using adult mice (n = 32) as an animal model, which were divided into water and cola groups depending on whether they received water or cola along with a standard rodent diet for 6 months. Micro-computed tomography revealed that cola intake did not significantly affect all measured parameters characterizing trabecular bone mass and microarchitecture, as well as cortical microarchitecture and geometry in both sexes, although a slight deterioration of these parameters was noted. Cola consumption also resulted in a slightly, statistically insignificant worsening of bone mechanical properties. In contrast to female mice, males receiving cola had a lower area of primary osteons' vascular canals. Nevertheless, long-term cola intake did not cause evident pathological alterations in the femur of adult mice, possibly due to a balanced diet and no restriction of physical activity. Therefore, the adverse effects of cola consumption on BMD, the only bone parameter studied so far, may be caused by other risk and lifestyle factors.

The Role of Macronutrients, Micronutrients and Flavonoid Polyphenols in the Prevention and Treatment of Osteoporosis

Osteoporosis is considered an age-related disorder of the skeletal system, characterized primarily by decreased bone mineral density (BMD), microstructural quality and an elevated risk of fragility fractures. This silent disease is increasingly becoming a global epidemic due to an aging population and longer life expectancy. It is known that nutrition and physical activity play an important role in skeletal health, both in achieving the highest BMD and in maintaining bone health. In this review, the role of macronutrients (proteins, lipids, carbohydrates), micronutrients (minerals—calcium, phosphorus, magnesium, as well as vitamins—D, C, K) and flavonoid polyphenols (quercetin, rutin, luteolin, kaempferol, naringin) which appear to be essential for the prevention and treatment of osteoporosis, are characterized. Moreover, the importance of various naturally available nutrients, whether in the diet or in food supplements, is emphasized. In addition to pharmacotherapy, the basis of osteoporosis prevention is a healthy diet rich mainly in fruits, vegetables, seafood and fish oil supplements, specific dairy products, containing a sufficient amount of all aforementioned nutritional substances along with regular physical activity. The effect of diet alone in this context may depend on an individual’s genotype, gene-diet interactions or the composition and function of the gut microbiota.

The emerging role of phosphorus in human health

Phosphorus, an essential nutrient, performs vital functions in skeletal and non-skeletal tissues and is pivotal for energy production. The last two decades of research on the physiological importance of phosphorus have provided several novel insights about its dynamic nature as a nutrient performing functions as a phosphate ion. Phosphorous also acts as a signaling molecule and induces complex physiological responses. It is recognized that phosphorus homeostasis is critical for health. The intake of phosphorus by the general population world-wide is almost double the amount required to maintain health. This increase is attributed to the incorporation of phosphate containing food additives in processed foods purchased by consumers. Research findings assessed the impact of excessive phosphorus intake on cells' and organs' responses, and highlighted the potential pathogenic consequences. Research also identified a new class of bioactive phosphates composed of polymers of phosphate molecules varying in chain length. These polymers are involved in metabolic responses including hemostasis, brain and bone health, via complex mechanism(s) with positive or negative health effects, depending on their chain length. It is amazing, that phosphorus, a simple element, is capable of exerting multiple and powerful effects. The role of phosphorus and its polymers in the renal and cardiovascular system as well as on brain health appear to be important and promising future research directions.

Phosphate, Microbiota and CKD

Phosphate is a key uremic toxin associated with adverse outcomes. As chronic kidney disease (CKD) progresses, the kidney capacity to excrete excess dietary phosphate decreases, triggering compensatory endocrine responses that drive CKD-mineral and bone disorder (CKD-MBD). Eventually, hyperphosphatemia develops, and low phosphate diet and phosphate binders are prescribed. Recent data have identified a potential role of the gut microbiota in mineral bone disorders. Thus, parathyroid hormone (PTH) only caused bone loss in mice whose microbiota was enriched in the Th17 cell-inducing taxa segmented filamentous bacteria. Furthermore, the microbiota was required for PTH to stimulate bone formation and increase bone mass, and this was dependent on bacterial production of the short-chain fatty acid butyrate. We review current knowledge on the relationship between phosphate, microbiota and CKD-MBD. Topics include microbial bioactive compounds of special interest in CKD, the impact of dietary phosphate and phosphate binders on the gut microbiota, the modulation of CKD-MBD by the microbiota and the potential therapeutic use of microbiota to treat CKD-MBD through the clinical translation of concepts from other fields of science such as the optimization of phosphorus utilization and the use of phosphate-accumulating organisms.

The Effects of Calcium, Magnesium, Phosphorus, Fluoride, and Lead on Bone Tissue

Bones are metabolically active organs. Their reconstruction is crucial for the proper functioning of the skeletal system during bone growth and remodeling, fracture healing, and maintaining calcium-phosphorus homeostasis. The bone metabolism and tissue properties are influenced by trace elements that may act either indirectly through the regulation of macromineral metabolism, or directly by affecting osteoblast and osteoclast proliferation or activity, or through becoming part of the bone mineral matrix. This study analyzes the skeletal impact of macroelements (calcium, magnesium, phosphorus), microelements (fluorine), and heavy metals (lead), and discusses the concentration of each of these elements in the various bone tissues.

Mineral Intake and Clinical Symptoms in Adult Patients with Hypophosphatasia

BACKGROUND

Hypophosphatasia (HPP) is a rare inherited metabolic disorder characterized by deficient activity of the tissue-nonspecific alkaline phosphatase entailing impaired turnover of phosphorus metabolites. Dietary mineral intake is suspected to influence clinical symptoms of HPP, but scientific evidence is missing.

METHODS

Cross-sectional matched-pairs study collecting comprehensive data on nutrient intake in 20 HPP patients and 20 unaffected, age- and gender-matched controls. Dietary information and clinical symptoms were documented in detail over 7 consecutive days using structured diaries.

RESULTS

Baseline data and type of energy-supplying nutrients were balanced between both groups. Median nutritional intake of phosphorus and calcium were significantly lower in HPP patients versus controls, which is partially attributable to lower energy consumption in HPP patients. Differences regarding phosphorus and calcium (Ca/P) ratio and uptake of magnesium, zinc, and vitamin B6 were not statistically significant. Both high (≥ 1375 mg/d) and low intakes (< 1100 mg/d) of phosphorus were significantly associated with an increased frequency of neuropsychiatric symptoms (P = 0.02). Similarly, very high and very low intake of calcium was significantly associated with musculoskeletal (P < 0.01), gastrointestinal (P = 0.02), and neuropsychiatric (P < 0.001) symptoms. An increased Ca/P ratio was associated with increased tiredness/fatigue (P < 0.01), whereas a decreased Ca/P was associated with gastrointestinal issues (P = 0.01).

CONCLUSION

Phosphorus and calcium intake seem reduced in HPP patients along with reduced total energy consumption. Particularly high as well as very low absolute or unbalanced phosphorus and calcium intake are associated with an increased frequency of clinical symptoms.

Greater consumption of noodle is associated with higher serum phosphorus levels: a cross-sectional study on healthy participants

Higher serum phosphorus levels are associated with mortality and cardiovascular events, both in healthy individuals and those with chronic kidney disease. Owing to the increasing westernization of eating habits, a decrease in rice consumption and an increase in the intake of bread and noodle products were observed in Japan. This cross-sectional study investigated the influence of staple food (rice, bread, and noodle) consumption patterns on the serum levels of phosphorus and phosphate-regulating factors in 103 healthy young participants. Fasting blood and 24-h urine samples were collected; data about dietary habits were collected using a brief-type self-administered diet history questionnaire. Cluster analysis was conducted to assess subgroups classified according to staple food consumption patterns. Serum levels of phosphorus and phosphate-regulating factors did not significantly differ between subgroups classified based on the frequency of rice or bread consumption. However, the serum levels of phosphorus and fibroblast growth factor 23 were more significantly elevated in the higher than in the lower noodle consumption frequency subgroup. Cluster analysis defined three clusters, and the serum phosphorus levels in the high-noodle cluster were significantly higher than that in the high-bread and high-rice clusters. A high consumption of noodles was associated with elevated serum phosphorus levels. The trial was registered in the University Hospital Medical Information Network (UMIN) Center system (The name of the trial register: Hidekazu Arai, and UMIN accession number: UMIN000034352).

The Role of Fibroblast Growth Factor 23 in Inflammation and Anemia

In patients with chronic kidney disease (CKD), adverse outcomes such as systemic inflammation and anemia are contributing pathologies which increase the risks for cardiovascular mortality. Amongst these complications, abnormalities in mineral metabolism and the metabolic milieu are associated with chronic inflammation and iron dysregulation, and fibroblast growth factor 23 (FGF23) is a risk factor in this context. FGF23 is a bone-derived hormone that is essential for regulating vitamin D and phosphate homeostasis. In the early stages of CKD, serum FGF23 levels rise 1000-fold above normal values in an attempt to maintain normal phosphate levels. Despite this compensatory action, clinical CKD studies have demonstrated powerful and dose-dependent associations between FGF23 levels and higher risks for mortality. A prospective pathomechanism coupling elevated serum FGF23 levels with CKD-associated anemia and cardiovascular injury is its strong association with chronic inflammation. In this review, we will examine the current experimental and clinical evidence regarding the role of FGF23 in renal physiology as well as in the pathophysiology of CKD with an emphasis on chronic inflammation and anemia.

Renal involvement in the pathogenesis of mineral and bone disorder in dystrophin-deficient mdx mouse

Duchenne muscular dystrophy is a severe muscular disorder, often complicated with osteoporosis, and impaired renal function has recently been featured. We aimed to clarify the involvement of renal function in the pathogenesis of mineral and bone disorder in mdx mice, a murine model of the disease. We clearly revealed renal dysfunction in adult mdx mice, in which dehydration and hypercalcemia were contributed. We also examined the effects of dietary phosphorus (P) overload on phosphate metabolism. Serum phosphate and parathyroid hormone (PTH) levels were significantly increased in mdx mice by dietary P in a dose-dependent manner; however, bone alkaline phosphatase levels were significantly lower in mdx mice. Additionally, bone mineral density in mdx mice were even worsened by increased dietary P in a dose-dependent manner. These results suggested that the uncoupling of bone formation and resorption was enhanced by skeletal resistance to PTH due to renal failure in mdx mice.

Habitual confectionery intake is associated with serum phosphorus levels : A cross-sectional study on healthy subjects

Hyperphosphatemia is associated with an increased risk of developing cardiovascular disease. Recently, it has been shown that high serum phosphorus levels are associated with increased cardiovascular events in healthy subjects, but the dietary factors determining serum phosphorus level have not been fully investigated. The study investigated the influence of habitual dietary factors on serum phosphorus levels in healthy young participants. This cross-sectional study conducted fasting blood sampling in 109 healthy young people and used a brief-type self-administered diet history questionnaire to evaluate the subject's habitual meals. Since the bioavailability of dietary phosphorus depends on the food sources, habitual phosphorus intakes from different food groups and intake frequency (times/month) of processed foods were calculated. The mean serum phosphorus level was 3.9 0.5 mg/dl ; 10.1% of the subjects had serum phosphorus levels that exceeded the reference levels of 4.5 mg/dl. Total phosphorus intake and phosphorus intake from animal-based food did not differ between serum phosphorus quartiles. Higher intake of confectionery was associated with increased serum phosphorus levels. This study showed that frequent consumption of confectionery was associated with elevated serum phosphorus levels. Additional studies are needed to determine whether this is a causal relationship. J. Med. Invest. 66 : 134-140, February, 2019.

Effects of the long-term feeding of diets enriched with inorganic phosphorus on the adult feline kidney and phosphorus metabolism

Renal disease has a high incidence in cats, and some evidence implicates dietary P as well. To investigate this further, two studies in healthy adult cats were conducted. Study 1 (36 weeks) included forty-eight cats, stratified to control or test diets providing 1·2 or 4·8 g/1000 kcal (4184 kJ) P (0 or approximately 3·6 g/1000 kcal (4184 kJ) inorganic P, Ca:P 1·2, 0·6). Study 2 (29 weeks) included fifty cats, stratified to control or test diets, providing 1·3 or 3·6 g/1000 kcal (4184 kJ) P (0 or approximately 1·5 g/1000 kcal (4184 kJ) inorganic P, Ca:P 1·2, 0·9). Health markers, glomerular filtration rate (GFR) and mineral balance were measured regularly, with abdominal ultrasound. Study 1 was halted after 4 weeks as the test group GFR reduced by 0·4 (95 % CI 0·3, 0·5) ml/min per kg, and ultrasound revealed changes in renal echogenicity. In study 2, at week 28, no change in mean GFR was observed (P >0·05); however, altered renal echogenicity was detected in 36 % of test cats. In agreement with previous studies, feeding a diet with Ca:P <1·0, a high total and inorganic P inclusion resulted in loss of renal function and changes in echogenicity suggestive of renal pathology. Feeding a diet containing lower total and inorganic P with Ca:P close to 1·0 led to more subtle structural changes in a third of test cats; however, nephrolithiasis occurred in both diet groups, complicating data interpretation. We conclude that the no observed adverse effects level for total dietary P in adult cats is lower than 3·6 g/1000 kcal (4184 kJ), however the effect of inorganic P sources and Ca:P require further investigation.

Prevention and treatment of hyperphosphatemia in chronic kidney disease

Hyperphosphatemia has consistently been shown to be associated with dismal outcome in a wide variety of populations, particularly in chronic kidney disease (CKD). Compelling evidence from basic and animal studies elucidated a range of mechanisms by which phosphate may exert its pathological effects and motivated interventions to treat hyperphosphatemia. These interventions consisted of dietary modifications and phosphate binders. However, the beneficial effects of these treatment methods on hard clinical outcomes have not been convincingly demonstrated in prospective clinical trials. In addition, exposure to high amounts of dietary phosphate may exert untoward actions even in the absence of overt hyperphosphatemia. Based on this concept, it has been proposed that the same interventions used in CKD patients with normal phosphate concentrations be used in the presence of hyperphosphatemia to prevent rise of phosphate concentration and as an early intervention for cardiovascular risk. This review describes conceptual models of phosphate toxicity, summarizes the evidence base for treatment and prevention of hyperphosphatemia, and identifies important knowledge gaps in the field.

Dietary Food-Additive Phosphate and Human Health Outcomes

Dietary intake of phosphorus is required for human health, and dietary reference intakes for phosphorus have been established. Food-grade phosphates are used as additives to provide a wide range of technical functions in food production. Phosphates are often the most efficient ingredients to provide the required functionality in many applications, and in some cases, there are not effective and approved alternatives. However, many investigators have expressed concern about the quantities of phosphorus and food-additive phosphate present in the diets of many populations. This paper presents the outcome of an extensive review of 110 primary research articles focused on identifying evidence that substantiates or refutes associations of total dietary phosphorus and food-additive phosphate intake with health and disease in humans. The lack of conclusive evidence prevented the drawing of firm conclusions about the safety and possible risks of food-additive phosphate in the general population, which is consonant with the overall assessments of authoritative institutions who have concluded that available data are insufficient to make the required determinations. Despite the inadequacy of the evidence currently available, many of the authors of the publications reviewed for this paper expressed concerns about the quantities of phosphorus and food-additive phosphate in the diets of the populations and subpopulations they studied. At the same time, most of these authors offered only qualified conclusions and expressed themselves tentatively. In addition, authors of primary research publications, authors of review articles, and authoritative institutions have called for the conduct of further research.

Acute tumoral calcinosis due to severe hyperphosphatemia in a maintenance hemodialysis patient

We report the case of a maintenance hemodialysis patient with severe hyperphosphatemia (26.6 mg/dL) who developed acute tumoral calcinosis. The patient started receiving maintenance hemodialysis after being diagnosed with type 2 diabetes mellitus. The patient's phosphate levels suddenly increased. He had not taken the prescribed phosphate binders for the past 5 years. He noticed swelling of the palmar aspects of his right thumb, which was diagnosed as tumoral calcinosis. His serum phosphate level reached 26.6 mg/dL. He started taking medication to lower his serum phosphate levels. The patient had a long history of eating convenience foods. As food additives in convenience foods could be a major source of phosphate, the patient corrected this habit by replacing convenience foods with special foods for dialysis patients. His symptoms improved along with the decrease in his serum phosphate levels. The main reason for the abrupt decrease in phosphate levels could be the correction of his dietary habits. Therefore, phosphate levels in processed foods should be carefully considered in dialysis patients.

Lack of Influence of Calcium/Phosphorus Ratio on Hip and Lumbar Bone Mineral Density in Older Americans: NHANES 2005-2006 Cross-Sectional Data

Objectives:

We sought to ascertain the effect of a low dietary calcium/phosphorus (Ca:P) ratio on the bone health of older adults in the United States. The present analysis assessed whether a high dietary consumption of P, which generally leads to a low dietary Ca:P ratio, has an unfavorable effect on the bone mineral density (BMD) of the hip and lumbar vertebrae in a representative sample of older US men and women.

Design:

For the 1228 men and women aged 50 to 70 and ≥71 years included in the National Health and Nutrition Examination Survey (NHANES) 2005 to 2006 cycle, quintiles of the dietary Ca:P ratio were tested for their association with hip and lumbar BMD after adjusting for body mass index (BMI). All data in this observational study were cross-sectional.

Results:

Women typically have higher dietary Ca:P ratios than men and lower BMDs. No trend emerged for any age or sex group when studying the relationship between the dietary Ca:P ratio and BMD with adjustment for BMI.

Conclusions:

A wide range of dietary Ca:P ratios in the diets of a cross-section of older adult men and women in the United States had little effect on the BMD of the hip (proximal femur) or the lumbar vertebrae (spine), even among those consuming large amounts of Ca supplements. Despite the lack of complete assessment of total P intake in the United States, these results suggest that high P consumption patterns and low dietary Ca:P ratios do not exert an adverse effect on BMD at major fracture sites in older adults.

Phosphorus Regulation in Chronic Kidney Disease

Serum phosphorus levels stay relatively constant through the influence of multiple factors-such as parathyroid hormone, fibroblast growth factor 23, and vitamin D-on the kidney, bone, and digestive system. Whereas normal serum phosphorus ranges between 3 mg/dL to 4.5 mg/dL, large cross-sectional studies have shown that even people with normal kidney function are sometimes found to have levels ranging between 1.6 mg/dL and 6.2 mg/dL. While this may partially be due to diet and the factors mentioned above, total understanding of these atypical ranges of serum phosphorus remains uncertain. Risks for bone disease are high in people aged 50 and older, and this group comprises a large proportion of people who also have chronic kidney disease. Consuming diets low in calcium and high in phosphorus, especially foods with phosphate additives, further exacerbates bone turnover. Existing bone disease increases the risk for high serum phosphorus, and higher serum phosphorus has been associated with increased adverse events and cardiovascular-related mortality both in people with chronic kidney disease and in those with no evidence of disease. Once kidney function has deteriorated to end-stage disease (Stage 5), maintaining normal serum phosphorus requires dietary restrictions, phosphate-binding medications, and dialysis. Even so, normal serum phosphorus remains elusive in many patients with Stage 5 kidney disease, and researchers are testing novel targets that may inhibit intestinal transport of phosphorus to achieve better phosphate control. Protecting and monitoring bone health should also aid in controlling serum phosphorus as kidney disease advances.

A High Phosphorus Diet Affects Lipid Metabolism in Rat Liver: A DNA Microarray Analysis

A high phosphorus (HP) diet causes disorders of renal function, bone metabolism, and vascular function. We previously demonstrated that DNA microarray analysis is an appropriate method to comprehensively evaluate the effects of a HP diet on kidney dysfunction such as calcification, fibrillization, and inflammation. We reported that type IIb sodium-dependent phosphate transporter is significantly up-regulated in this context. In the present study, we performed DNA microarray analysis to investigate the effects of a HP diet on the liver, which plays a pivotal role in energy metabolism. DNA microarray analysis was performed with total RNA isolated from the livers of rats fed a control diet (containing 0.3% phosphorus) or a HP diet (containing 1.2% phosphorus). Gene Ontology analysis of differentially expressed genes (DEGs) revealed that the HP diet induced down-regulation of genes involved in hepatic amino acid catabolism and lipogenesis, while genes related to fatty acid β-oxidation process were up-regulated. Although genes related to fatty acid biosynthesis were down-regulated in HP diet-fed rats, genes important for the elongation and desaturation reactions of omega-3 and -6 fatty acids were up-regulated. Concentrations of hepatic arachidonic acid and eicosapentaenoic acid were increased in HP diet-fed rats. These essential fatty acids activate peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor for fatty acid β-oxidation. Evaluation of the upstream regulators of DEGs using Ingenuity Pathway Analysis indicated that PPARα was activated in the livers of HP diet-fed rats. Furthermore, the serum concentration of fibroblast growth factor 21, a hormone secreted from the liver that promotes fatty acid utilization in adipose tissue as a PPARα target gene, was higher (p = 0.054) in HP diet-fed rats than in control diet-fed rats. These data suggest that a HP diet enhances energy expenditure through the utilization of free fatty acids released via lipolysis of white adipose tissue.

Intakes of Calcium and Phosphorus and Calculated Calcium-to-Phosphorus Ratios of Older Adults: NHANES 2005-2006 Data

Background: High intakes of dietary phosphorus (P), relative to calcium (Ca) intake, are associated with a lower calcium:phosphorus ratio (Ca:P) ratio which potentially has adverse health effects, including arterial calcification, bone loss, and death. A substantial percentage of older adults (50 to 70 and 71 plus years) who have a higher risk of fracture rate than younger adults typically have low intakes of dietary Ca that are dominated by higher intakes of dietary P from natural and fortified foods, and lower Ca:P ratios than desirable. Objective: This investigation was undertaken to examine Ca and P intakes and the resulting Ca:P ratios (by mass) across gender and older adult age groups, using data from the National Health and Nutrition Examination Survey (NHANES) 2005–2006. Design: NHANES data are based on a cross-sectional sample of the non-institutionalized United States (US) population within various regions. This sample is selected to be representative of the entire US population at all ages. National Cancer Institute (NCI) methods and SAS survey procedures were used for analyses. Ca:P ratios were calculated using total Ca from both foods and supplements, whereas P intakes were calculated from food composition values and supplements. The amounts of P additives in processed foods are not available. Results: Mean Ca and P intakes demonstrated lower intakes of Ca and higher intakes of P compared to current Recommended Dietary Allowances (RDAs). The Ca:P ratios in older male and female adults were influenced by both low-Ca and high-P dietary consumption patterns. Conclusions: Both low total Ca intakes and high P amounts contribute to lower Ca:P ratios, i.e., ~0.7:1.0, in the consumption patterns of older adults than is recommended by the RDAs, i.e., ~1.5:1.0. Whether Ca:P ratios lower than recommended contribute to increased risk of bone loss, arterial calcification, and all-cause mortality cannot be inferred from these data. Additional amounts of chemical P additives in the food supply may actually reduce even further the Ca:P ratios of older adults of both genders, but, without P additive data from the food industry, calculation of more precise ratios from NHANES 2005–2006 data is not possible.

Bone Mineral Density and Protein-Derived Food Clusters from the Framingham Offspring Study

BACKGROUND

Dietary protein is beneficial to bone health; however, dietary patterns of protein intake and their relationship with bone mineral density (BMD) have not been evaluated.

OBJECTIVE

To examine the relationship of dietary protein food clusters with BMD at the femoral neck, trochanter, total femur, and lumbar spine among middle-aged and older men and women.

DESIGN

Cross-sectional study.

PARTICIPANTS AND SETTING

Two thousand seven hundred fifty-eight community-dwelling individuals from the Framingham Offspring Study.

METHODS

BMD was measured by Lunar DPX-L (Lunar Radiation Corporation) in 1996-2001. Dietary intakes were estimated using the Willett food frequency questionnaire in either 1995-1998 or 1998-2001, and the exam closest to a participant's BMD measurement was used. Cluster analysis (FASTCLUS procedure, k-means method) was used to classify participants into groups, determined by major sources of protein. Generalized linear regression was used to compare adjusted least-squares mean BMD across protein food clusters for all pairwise comparisons.

RESULTS

From 2,758 participants (44% men; mean age 61±9 years, range=29 to 86 years), five protein food clusters were identified (chicken, fish, processed foods, red meat, and low-fat milk). Three of these food clusters showed associations with BMD. The red meat protein food cluster presented with significantly lower femoral neck BMD compared with the low-fat milk cluster (red meat 0.898±0.005 g/cm(2) vs low-fat milk 0.919±0.007 g/cm(2); P=0.04). Further, the processed foods protein cluster presented with significantly lower femoral neck BMD compared with the low-fat milk cluster (processed foods 0.897±0.004 g/cm(2) vs low-fat milk 0.919±0.007 g/cm(2); P=0.02). A similar, yet nonsignificant, trend was observed for other BMD sites examined.

CONCLUSIONS

Diets with the greatest proportion of protein intake from red meat and processed foods may not be as beneficial to the skeleton compared with dietary patterns where the highest proportion of protein is derived from low-fat milk.

Association between phosphorus intake and bone health in the NHANES population

The objective of this study was to estimate the independent associations between intake of phosphorus (P) and bone health parameters such as bone mineral content (BMC) and bone mineral density (BMD). It provides odds ratio (OR) of osteoporosis with quartiles of P intake adjusted for covariates (i.e., age, gender, BMI, and consumption of calcium (Ca), protein, total dairy foods, and vitamin D as well as intakes of supplemental Ca, vitamin D, and multivitamins/minerals). Data came from males and females aged 13–99 years who participated in the 2005–2010 National Health and Nutrition Examination Survey (NHANES). Analyses showed that higher P intake was associated with higher Ca intake, and that dietary Ca:P ratios (0.51-0.62, with a mean of 0.60 for adults) were adequate in all age/gender groups. High intake of P was positively associated with BMC in female teenagers (Q4 vs. Q1: BMC, 30.9 ± 1.1 vs. 29.0 ± 0.5 g, P = 0.001). It was also positively associated with BMC and BMD as well as reduced risk of osteoporosis in adults >20 years of age (Q4 vs. Q1: OR of osteoporosis, 0.55; 95% confidence interval [CI], 0.39- 0.79; P = 0.001; BMC, 37.5 ± 0.4 vs. 36.70 ± 0.3 g, P < 0.01; BMD, 0.986 ± 0.004 vs. 0.966 ± 0.005 g/cm², P < 0.05). The data suggest that high intake of P has no adverse effect on bone metabolism in populations with adequate Ca intake, and that it is also associated with positive bone parameters in some age/gender groups.

High dietary phosphate intake induces development of ectopic calcifications in a murine model of familial tumoral calcinosis

Familial tumoral calcinosis is characterized by ectopic calcifications due to persistent hyperphosphatemia. The most common genetic cause of the disease is mutations in GALNT3, encoding a glycosyltransferase involved in a posttranslational modification of fibroblast growth factor 23 (FGF23). The Galnt3 knockout mouse we developed was hyperphosphatemic due to low intact Fgf23 levels, but did not develop any apparent calcifications on a standard rodent diet. We therefore tested the hypothesis that a further challenge with a high phosphate diet could induce ectopic calcifications in Galnt3 knockout mice. Mice were fed either normal (0.6%) or high (1.65%) phosphate diet for 20 weeks beginning from weaning at 3 weeks. The high phosphate diet did not affect serum phosphorus concentration. However, regardless of the dietary phosphate contents, serum phosphorus levels were consistently elevated in Galnt3 knockout mice. The mice on the high phosphate diet had slightly low serum calcium, but significantly high alkaline phosphatase, parathyroid hormone (PTH), and calcium in the kidney. Although none of Galnt3 knockout mice on the normal phosphate diet developed calcifications, calcifications appeared in approximately one-half of the mice on the high phosphate diet by 12 weeks. Calcified masses were most often found around the neck and on the back and as large as 9.9 mm in length. These data indicate that dietary phosphate load has major impact on the development of ectopic calcifications in tumoral calcinosis.

Is phosphorus intake that exceeds dietary requirements a risk factor in bone health?

Phosphorus intake in excess of the nutrient needs of healthy adults is thought to disrupt hormonal regulation of phosphorus (P), calcium (Ca), and vitamin D, contributing to impaired peak bone mass, bone resorption, and greater risk of fracture. Elevation of extracellular phosphorus due to excessive intake is thought to be the main stimulus disrupting phosphorus homeostasis in healthy individuals, as it is in renal disease even when intake is modest. If high serum phosphorus is the critical link to the effect of high phosphorus intake on bone health, the issue could be addressed through epidemiologic or dietary studies. However, several confounding factors, including problems estimating accurate phosphorus intake, the influence of a low dietary Ca:P ratio, the acidic nature of phosphorus, the rapid rate of absorption and greater phosphorus bioavailability from processed food such as cola drinks, and circadian fluctuation in serum phosphorus, make this question difficult to address using conventional study designs. These confounding factors are considered in this review, exploring whether phosphorus intake exceeding nutrient needs in healthy individuals disrupts phosphorus regulation and negatively affects bone accretion or loss. Specific attention is given to phosphorus intake from processed foods rich in phosphorus additives, which significantly contribute to phosphorus intake.

Assessing the health impact of phosphorus in the food supply: issues and considerations

The Western dietary pattern of intake common to many Americans is high in fat, refined carbohydrates, sodium, and phosphorus, all of which are associated with processed food consumption and higher risk of life-threatening chronic diseases. In this review, we focus on the available information on current phosphorus intake with this Western dietary pattern, and new knowledge of how the disruption of phosphorus homeostasis can occur when intake of phosphorus far exceeds nutrient needs and calcium intake is limited. Elevation of extracellular phosphorus, even when phosphorus intake is seemingly modest, but excessive relative to need and calcium intake, may disrupt the endocrine regulation of phosphorus balance in healthy individuals, as it is known to do in renal disease. This elevation in serum phosphate, whether episodic or chronically sustained, may trigger the secretion of regulatory hormones, whose actions can damage tissue, leading to the development of cardiovascular disease, renal impairment, and bone loss. Therefore, we assessed the health impact of excess phosphorus intake in the context of specific issues that reflect changes over time in the U.S. food supply and patterns of intake. Important issues include food processing and food preferences, the need to evaluate phosphorus intake in relation to calcium intake and phosphorus bioavailability, the accuracy of various approaches used to assess phosphorus intake, and the difficulties encountered in evaluating the relations of phosphorus intake to chronic disease markers or incident disease.

Increasing dietary phosphorus intake from food additives: potential for negative impact on bone health

It is important to consider whether habitual high phosphorus intake adversely affects bone health, because phosphorus intake has been increasing, whereas calcium intake has been decreasing in dietary patterns. A higher total habitual dietary phosphorus intake has been associated with higher serum parathyroid hormone (PTH) and lower serum calcium concentrations in healthy individuals. Higher serum PTH concentrations have been shown in those who consume foods with phosphorus additives. These findings suggest that long-term dietary phosphorus loads and long-term hyperphosphatemia may have important negative effects on bone health. In contrast, PTH concentrations did not increase as a result of high dietary phosphorus intake when phosphorus was provided with adequate amounts of calcium. Intake of foods with a ratio of calcium to phosphorus close to that found in dairy products led to positive effects on bone health. Several randomized controlled trials have shown positive relations between dairy intake and bone mineral density. In our loading test with a low-calcium, high-phosphorus lunch provided to healthy young men, serum PTH concentrations showed peaks at 1 and 6 h, and serum fibroblast growth factor 23 (FGF23) concentrations increased significantly at 8 h after the meal. In contrast, the high-calcium, high-phosphorus meal suppressed the second PTH and FGF23 elevations until 8 h after the meal. This implies that adequate dietary calcium intake is needed to overcome the interfering effects of high phosphorus intake on PTH and FGF23 secretion. FGF23 acts on the parathyroid gland to decrease PTH mRNA and PTH secretion in rats with normal kidney function. However, increased serum FGF23 is an early alteration of mineral metabolism in chronic kidney disease, causing secondary hyperthyroidism, and implying resistance of the parathyroid gland to the action of FGF23 in chronic kidney disease. These findings suggest that long-term high-phosphorus diets may impair bone health mediated by FGF23 resistance both in chronic kidney disease patients and in the healthy population.

Associations among total and food additive phosphorus intake and carotid intima-media thickness--a cross-sectional study in a middle-aged population in Southern Finland

Background

Dietary phosphorus (P) intake in Western countries is 2- to 3-fold higher than recommended, and phosphate is widely used as a food additive in eg. cola beverages and processed meat products. Elevated serum phosphate concentrations have been associated with cardiovascular disease (CVD) risk factors and CVD itself in several studies in patients with renal dysfunction and in a few studies in the general population. Carotid intima-media thickness (IMT) is a CVD risk factor, thus the aim of the study was to determine if an association between dietary P, especially food additive phosphate (FAP), intake, and IMT exists.

Methods

Associations among total phosphorus (TP) and FAP intake and carotid IMT were investigated in a cross-sectional study of 37- to 47-year-old females (n = 370) and males (n = 176) in Finland. Associations among TP intake, FAP intake, and IMT were tested by analysis of covariance (ANCOVA) in quintiles (TP) and sextiles (FAP) using sex, age, low-density/high-density lipoprotein cholesterol ratio, smoking status, and IMT sonographer as covariates.

Results

No significant associations were present between TP or FAP intake and IMT (p > 0.05, ANCOVA), but in between-group comparisons some differences were found indicating higher IMT among subjects with higher P intake. When testing for a significant linear trend with contrast analysis, a positive trend was observed between energy-adjusted TP intake and IMT among all subjects (p = 0.039), and among females a tendency for a trend existed (p = 0.067). Among all subjects, a significant positive linear trend was also present between FAP intake and IMT (p = 0.022); this trend was also seen in females (p = 0.045). In males, no significant associations or trends were noted between TP or FAP intake and IMT (p > 0.05).

Conclusions

Our results indicate that a significant linear trend exists between energy-adjusted TP intake and FAP intake, and IMT among all subjects. Based on these results, high dietary P intake should be further investigated due to its potential association with adverse cardiovascular health effects in the general population.

The prevalence of phosphorus-containing food additives in top-selling foods in grocery stores

OBJECTIVE

The objective of this study was to determine the prevalence of phosphorus-containing food additives in best-selling processed grocery products and to compare the phosphorus content of a subset of top-selling foods with and without phosphorus additives.

DESIGN

The labels of 2394 best-selling branded grocery products in northeast Ohio were reviewed for phosphorus additives. The top 5 best-selling products containing phosphorus additives from each food category were matched with similar products without phosphorus additives and analyzed for phosphorus content. Four days of sample meals consisting of foods with and without phosphorus additives were created, and daily phosphorus and pricing differentials were computed.

MAIN OUTCOME MEASURES

Presence of phosphorus-containing food additives, phosphorus content.

RESULTS

Forty-four percent of the best-selling grocery items contained phosphorus additives. The additives were particularly common in prepared frozen foods (72%), dry food mixes (70%), packaged meat (65%), bread and baked goods (57%), soup (54%), and yogurt (51%) categories. Phosphorus additive-containing foods averaged 67 mg phosphorus/100 g more than matched nonadditive-containing foods (P = .03). Sample meals comprised mostly of phosphorus additive-containing foods had 736 mg more phosphorus per day compared with meals consisting of only additive-free foods. Phosphorus additive-free meals cost an average of $2.00 more per day.

CONCLUSION

Phosphorus additives are common in best-selling processed groceries and contribute significantly to their phosphorus content. Moreover, phosphorus additive foods are less costly than phosphorus additive-free foods. As a result, persons with chronic kidney disease may purchase these popular low-cost groceries and unknowingly increase their intake of highly bioavailable phosphorus.

Public health impact of dietary phosphorus excess on bone and cardiovascular health in the general population

This review explores the potential adverse impact of the increasing phosphorus content in the American diet on renal, cardiovascular, and bone health of the general population. Increasingly, studies show that phosphorus intakes in excess of the nutrient needs of a healthy population may significantly disrupt the hormonal regulation of phosphate, calcium, and vitamin D, which contributes to disordered mineral metabolism, vascular calcification, impaired kidney function, and bone loss. Moreover, large epidemiologic studies suggest that mild elevations of serum phosphate within the normal range are associated with cardiovascular disease (CVD) risk in healthy populations without evidence of kidney disease. However, few studies linked high dietary phosphorus intake to mild changes in serum phosphate because of the nature of the study design and inaccuracies in the nutrient composition databases. Although phosphorus is an essential nutrient, in excess it could be linked to tissue damage by a variety of mechanisms involved in the endocrine regulation of extracellular phosphate, specifically the secretion and action of fibroblast growth factor 23 and parathyroid hormone. Disordered regulation of these hormones by high dietary phosphorus may be key factors contributing to renal failure, CVD, and osteoporosis. Although systematically underestimated in national surveys, phosphorus intake seemingly continues to increase as a result of the growing consumption of highly processed foods, especially restaurant meals, fast foods, and convenience foods. The increased cumulative use of ingredients containing phosphorus in food processing merits further study given what is now being shown about the potential toxicity of phosphorus intake when it exceeds nutrient needs.

Dietary vitamin D intake is not associated with 25-hydroxyvitamin D3 or parathyroid hormone in elderly subjects, whereas the calcium-to-phosphate ratio affects parathyroid hormone

This cross-sectional study investigates whether serum 25-hydroxyvitamin D3 [25(OH)D3] and intact parathyroid hormone (iPTH) are affected by vitamin D, calcium, or phosphate intake in 140 independently living elderly subjects from Germany (99 women and 41 men; age, 66-96 years). We hypothesized that habitual dietary intakes of vitamin D, calcium, and phosphate are not associated with 25(OH)D3 or iPTH and that body mass index confounds these associations. Serum 25(OH)D3 and iPTH were measured by an electrochemiluminescence immunoassay. Dietary intake was determined using a 3-day estimated dietary record. The median dietary intake levels of vitamin D, calcium, and phosphate were 3 μg/d, 999 mg/d, and 1250 mg/d, respectively. Multiple regression analyses confirmed that dietary vitamin D and calcium did not affect 25(OH)D3 or iPTH; however, supplemental intakes of vitamin D and calcium were associated with 25(OH)D3 after adjustment for age, sex, body composition, sun exposure, physical activity, and smoking. In addition, phosphate intake and the calcium-to-phosphate ratio were associated with iPTH after multiple adjustments. In a subgroup analysis, calcium and vitamin D supplements, as well as phosphate intake, were associated with 25(OH)D3 and/or iPTH in normal-weight subjects only. Our results indicate that habitual dietary vitamin D and calcium intakes have no independent effects on 25(OH)D3 or iPTH in elderly subjects without vitamin D deficiency, whereas phosphate intake and the calcium-to-phosphate ratio affect iPTH. However, vitamin D and calcium supplements may increase 25(OH)D3 and decrease iPTH, even during the summer, but the impact of supplements may depend on body mass index.

Sodium- and phosphorus-based food additives: persistent but surmountable hurdles in the management of nutrition in chronic kidney disease

Sodium- and phosphorus-based food additives are among the most commonly consumed nutrients in the world. This is because both have diverse applications in processed food manufacturing, leading to their widespread use by the food industry. Since most foods are naturally low in salt, sodium additives almost completely account for the excessive consumption of sodium throughout the world. Similarly, phosphorus additives represent a major and "hidden" phosphorus load in modern diets. These factors pose a major barrier to successfully lowering sodium or phosphorus intake in patients with CKD. As such, any serious effort to reduce sodium or phosphorus consumption will require reductions in the use of these additives by the food industry. The current regulatory environment governing the use of food additives does not favor this goal, however, in large part because these additives have historically been classified as generally safe for public consumption. To overcome these barriers, coordinated efforts will be needed to demonstrate that high intake of these additives is not safe for public consumption and as such should be subject to greater regulatory scrutiny.

Inorganic Phosphate as a Novel Signaling Molecule with Antiproliferative Action in MDA-MB-231 Breast Cancer Cells

Inorganic phosphate (Pi) is an essential nutrient for living organisms. It plays a key role in diverse physiological functions, including osteoblast differentiation and skeletal mineralization. Relevantly, Pi is emerging as an important signaling molecule capable of modulating multiple cellular functions by altering signal transduction pathways, gene expression, and protein abundance in many cell types. To our knowledge, the consequences of elevated Pi on behavior of breast cancer cells have been poorly addressed. In this study we investigate the effects of Pi on proliferation of MDA-MB-231 breast cancer cells. We report that Pi inhibits proliferation of MDA-MB-231 cells by slowing cell cycle progression, without apoptosis occurrence. We found that Pi causes cells to accumulate in G1 phase in a time-dependent manner. Accordingly, G1 accumulation was associated with a decrease of cyclin A and cyclin E and an increase of cell cycle inhibitors p21 and p27 protein levels, respectively. Moreover, the Pi-induced antiproliferative effect was dynamically accompanied by profound changes in ERK1/2 and STAT3 protein and phosphorylation levels in response to Pi. Altogether, our data represent the first evidence of Pi acting as a novel signaling molecule in MDA-MB-231 breast cancer cells, capable of eliciting a strong antiproliferative action and suggest that targeting Pi levels at local sites might represent the rationale for developing novel strategies for therapeutic intervention in triple-negative breast cancer.

Dietary phosphorus is associated with greater left ventricular mass

Dietary phosphorus consumption has risen steadily in the United States. Oral phosphorus loading alters key regulatory hormones and impairs vascular endothelial function which may lead to an increase in left ventricular mass (LVM). We investigated the association of dietary phosphorus with LVM in 4,494 participants from the Multi-Ethnic Study of Atherosclerosis, a community-based study of individuals free of known cardiovascular disease. The intake of dietary phosphorus was estimated using a 120-item food frequency questionnaire and the LVM was measured using magnetic resonance imaging. Regression models were used to determine associations of estimated dietary phosphorus with LVM and left ventricular hypertrophy (LVH). Mean estimated dietary phosphorus intake was 1,167 mg/day in men and 1,017 mg/day in women. After adjustment for demographics, dietary sodium, total calories, lifestyle factors, comorbidities, and established LVH risk factors, each quintile increase in the estimated dietary phosphate intake was associated with an estimated 1.1 gram greater LVM. The highest gender-specific dietary phosphorus quintile was associated with an estimated 6.1 gram greater LVM compared to the lowest quintile. Higher dietary phosphorus intake was associated with greater odds of LVH among women, but not men. These associations require confirmation in other studies.

Mono- and polyphosphates have similar effects on calcium and phosphorus metabolism in healthy young women

PURPOSE

Phosphate (Pi) salts, often mono- (MP) or polyphosphates (PP), are commonly used as additives in the food industry. Previous studies have shown that the effects of MP and PP on calcium (Ca) and phosphorus (P) metabolism may differ. The aim of this study was to determine whether the effects of MP and PP salts differ on markers of Ca and P metabolism in young women.

METHODS

Fourteen healthy women 19-31 years of age were randomized into three controlled 24-h study sessions, each subject serving as her own control. During each session, the subjects received three doses of MP, PP or a placebo with meals in randomized order. Both Pi salts provided 1,500 mg P/d, and the diet during each session was identical. Markers of Ca and P metabolism were followed six times over 24 h.

RESULTS

During both MP and PP sessions, we found an increase in serum phosphate (S-Pi, p = 0.0001), urinary phosphate (U-Pi, p = 0.0001) and serum parathyroid hormone (S-PTH, p = 0.048 MP, p = 0.012 PP) relative to the control session. PP decreased U-Ca more than did MP (p = 0.014).

CONCLUSIONS

The results suggest that PP binds Ca in the intestine more than does MP. Based on the S-Pi, U-Pi and S-PTH results, both Pi salts are absorbed with equal efficiency. In the long run, increased S-PTH, caused by either an MP or PP salt, could have negative effects on bone metabolism.

Effect of the use of a commercial phosphate mixture on selected quality characteristics of 2 Spanish-style dry-ripened sausages

The aim of this study was to evaluate the usefulness of the addition of a commercial phosphate mixture in 2 dry-ripened Spanish-style sausages: "salchichón" and "chorizo." Three batches of each of those sausages were prepared with low and high levels of phosphates, and selected quality variables (moisture, pH, a(w) , lactic and acetic acid, α-amino nitrogen, total free fatty acids, thiobarbituric acid reactive substances, microbial counts, color, and texture analysis) were compared against controls. Furthermore, phosphate-added and control sausages were ranked by consumers in order of preference. In "salchichón," phosphate addition resulted in a significant (P < 0.05) increase in drying rate, and tendencies (not significant) toward a decrease in lipid oxidation and an increase in hardness and chewiness. In "chorizo," the addition of phosphates resulted in higher hardness, elasticity and chewiness, and lower yellowness (P < 0.05). In the manufacture process of dry-ripened sausages, phosphates can be considered as additives with potential enhancement effect in drying and eating quality.

PRACTICAL APPLICATION

The main outcome from the present study is to find evidence on which points of reference could be drawn for the technological application of phosphates in dry-ripened sausages. It has been observed that the drying rate and several eating quality characteristics can be enhanced with the use of phosphates.

Differences among total and in vitro digestible phosphorus content of meat and milk products

OBJECTIVE

Meat and milk products are important sources of dietary phosphorus (P) and protein. The use of P additives is common both in processed cheese and meat products. Measurement of in vitro digestible phosphorus (DP) content of foods may reflect absorbability of P. The objective of this study was to measure both total phosphorus (TP) and DP contents of selected meat and milk products and to compare amounts of TP and DP and the proportion of DP to TP among different foods.

METHODS

TP and DP contents of 21 meat and milk products were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). In DP analysis, samples were digested enzymatically, in principle, in the same way as in the alimentary canal before the analyses. The most popular national brands of meat and milk products were chosen for analysis.

RESULTS

The highest TP and DP contents were found in processed and hard cheeses; the lowest, in milk and cottage cheese. TP and DP contents in sausages and cold cuts were lower than those in cheeses. Chicken, pork, beef, and rainbow trout contained similar amounts of TP, but slightly more variation was found in their DP contents.

CONCLUSIONS

Foods containing P additives have a high content of DP. Our study confirms that cottage cheese and unenhanced meats are better choices than processed or hard cheeses, sausages, and cold cuts for chronic kidney disease patients, based on their lower P-to-protein ratios and sodium contents. The results support previous findings of better P absorbability in foods of animal origin than in, for example, legumes.

Differences among total and in vitro digestible phosphorus content of plant foods and beverages

OBJECTIVE

Among plant foods, grain products, legumes, and seeds are important sources of phosphorus (P). Current data on P content and absorbability of P from these foods are lacking. Measurement of in vitro digestible P (DP) content of foods may reflect absorbability of P. The objective of this study was to measure both total phosphorus (TP) and DP contents of selected foods and to compare the amounts of TP and DP and the proportion of DP to TP among different foods.

METHODS

TP and DP content of 21 foods and drinks of plant origin were measured by inductively coupled plasma optical emission spectrometry. In DP analysis, samples were digested enzymatically in principle in the same way as in the alimentary canal before P analyses. The most popular national brands were chosen for analysis.

RESULTS

The highest amount of TP (667 mg/100 g) was found in sesame seeds with hull, which also had the lowest percentage of DP (6%) to TP. Instead, in cola drinks and beer, the percentage of DP to TP was 87 to 100% (13 to 22 mg/100 g). In cereal products, the highest TP content (216 mg/100 g) and DP proportion (100%) were present in industrial muffins, which contain sodium phosphate as a leavening agent. Legumes contained an average DP content of 83 mg/100 g (38% of TP).

CONCLUSION

Absorbability of P may differ substantially among different plant foods. Despite high TP content, legumes may be a relatively poor P source. In foods containing phosphate additives, the proportion of DP is high, which supports previous conclusions of the effective absorbability of P from P additives.