Dietary phosphorus sources and their acute effects on mineral metabolism in healthy women

A high P intake is deleterious to chronic kidney disease (CKD) patients, but based on more recent data, it has also been associated with an increased risk of osteoporosis and cardiovascular diseases in the general population. In addition to several natural sources of P (especially dairy products, meats, whole grains, legumes, and eggs), the use of P additives in the food industry is common and further increases P intake. In this thesis, P contents of foods were analysed and the effects of different P sources on mineral metabolism were compared in healthy young female subjects. In Studies I and II, the objective was to measure both total phosphorus (TP) and in vitro digestible phosphorus (DP) contents of selected foods and to compare the amounts of TP and DP and the proportion of DP to TP among different foods. In DP analysis, samples were digested enzymatically in principle in the same way as in the alimentary canal before P analyses. The results suggest that the absorbability of P may differ substantially among different 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. Among foods of animal origin, the highest TP and DP contents were found in processed and hard cheeses; the lowest, in milk and cottage cheese. Studies III and IV were controlled intervention studies in healthy young women. Each subject served as her own control, and the order of the study sessions was randomized. Markers of mineral metabolism from blood and urine samples were measured. In Study III, acute effects of dietary P from three different food sources (meat, cheese and whole grains) and a phosphate supplement on calcium (Ca) and bone metabolism were investigated. Only the phosphate supplement increased serum parathyroid hormone (S-PTH) concentration compared with the control session. Relative to the control session, meat increased markers of both bone formation and bone resorption. Cheese decreased S-PTH and bone resorption. These data suggest that the metabolic response was different for different foods. The purpose of Study IV was to determine whether the effects of mono- and polyphosphate salts (MP and PP, respectively) used as additives differ on markers of Ca and P metabolism in young women. In both MP and PP sessions, serum phosphate, urinary phosphate, and S-PTH increased relative to the control session. PP decreased urinary Ca more than did MP. The results suggest that PP binds Ca in the intestine better than does MP. In the long run, increased S-PTH, caused by either an MP or PP salt, could have negative effects on bone metabolism. In summary, the studies support the previous understanding of differences in P absorbability and mineral metabolism. This is relevant regarding the diets of CKD patients, but may also have a wider relevance if the significance of high P intake in the aetiology of cardiovascular diseases and osteoporosis is confirmed.Runsas fosforin saanti on haitallista kroonisesta munuaisten vajaatoiminnasta kärsiville, mutta viimeaikaisten tutkimusten perusteella se saattaa lisätä myös sydän- ja verisuonitautien sekä osteoporoosin riskiä väestötasolla. Fosforia saadaan luontaisesti useista eri lähteistä kuten maidosta, lihasta, viljasta, palkoviljasta ja kananmunista. Fosforin saanti on kuitenkin lisääntynyt myös elintarviketeollisuuden kasvaneen lisäainefosfaattien käytön seurauksena. Tässä väitöskirjassa tutkittiin elintarvikkeiden fosforipitoisuuksia sekä verrattiin eri fosforilähteiden vaikutuksia mineraaliaineenvaihduntaan terveillä nuorilla naisilla. Ensimmäisessä ja toisessa osatyössä määritettiin yhteensä 42 fosforin saannin kannalta keskeisen tuotteen kokonais- ja liukoisen fosforin pitoisuus sekä vertailtiin liukoisen fosforin osuutta kokonaisfosforista eri elintarvikkeiden välillä. Liukoisen fosforin pitoisuus kuvaa sitä osuutta kokonaisfosforista, joka imeytyy suolistosta verenkiertoon. Tulosten perusteella fosforin imeytyvyys eri tuotteiden välillä voi vaihdella paljon. Huolimatta suuresta kokonaisfosforipitoisuudesta palkoviljatuotteet voivat olla melko huonoja fosforilähteitä. Lisäainefosforia sisältävissä tuotteissa liukoisen fosforin osuus oli huomattavan suuri, mikä tukee aiempaa käsitystä fosforin tehokkaasta imeytyvyydestä epäorgaanisista fosfaattiyhdisteistä. Kolmas ja neljäs osatyö olivat ajan ja ravinnon suhteen kontrolloituja interventiotutkimuksia nuorilla naisilla. Kolmannessa osatyössä tutkittiin neljän eri fosforilähteen (liha, vilja, juusto ja lisäainefosfaattiseos) akuutteja vaikutuksia mineraaliaineenvaihduntaan 15 terveellä nuorella naisella. Tutkimuksessa todettiin ainoastaan lisäainefosfaattiseoksen nostavan seerumin lisäkilpirauhashormonin (PTH) pitoisuutta. Pitkään jatkuessaan koholla oleva seerumin PTH-pitoisuus on haitallista luustolle. Vilja nosti seerumin fosfaattipitoisuutta vähemmän kuin muut fosforilähteet, mikä viittaa siihen, että viljan fosfori on huonommin imeytyvää kuin muista fosforilähteistä peräisin oleva fosfori. Fosforilähteiden vaikutukset mineraaliaineenvaihduntaan poikkesivat siis toisistaan johtuen fosforin erilaisesta imeytyvyydestä ja fosforilähteiden sisältämistä muista ravintoaineista. Neljännessä osatyössä vertailtiin kahden eri lisäainefosfaattiyhdisteen, mono- ja polyfosfaatin, vaikutuksia fosfori- ja kalsiumaineenvaihdunnan merkkiaineisiin 14 terveellä nuorella naisella. Molemmat fosfaattiyhdisteet nostivat seerumin PTH- ja fosfaattipitoisuutta sekä lisäsivät fosfaatin eritystä virtsaan. Polyfosfaatti vähensi kalsiumin eritystä virtsaan monofosfaattia voimakkaammin, joten se saattaa sitoa kalsiumia suolessa monofosfaattia enemmän. Molemmat fosfaattiyhdisteet vaikuttaisivat imeytyvän yhtä tehokkaasti ja nostavan seerumin PTH-pitoisuutta. Väitöskirjan tulokset tukevat aiempaa käsitystä siitä, että fosforilähteiden välillä on eroja imeytyvyydessä ja vaikutuksessa mineraaliaineenvaihduntaan. Tällä on merkitystä kroonisesta munuaisten vajaatoiminnasta kärsivien ruokavaliossa, ja ehkä myös laajemmalti, mikäli runsaan fosforin saannin merkitys myös sydän- ja verisuonitautien ja osteoporoosin syytekijänä vahvistuu

Phosphorus-Containing Food Additives in the Food Supply-An Audit of Products on Supermarket Shelves

Objectives: Phosphorus (P)-containing food additives pose a risk for chronic kidney disease (CKD) patients. We aimed to investigate the prevalence of P-containing additives in the Finnish food supply across different food categories to evaluate their burden in CKD, reflecting the situation in Europe. Methods: The dataset of 6,176 products was obtained in June-August 2019 from the foodie.fi website, which contains all foodstuffs sold in the grocery stores of the S Group (46% of the Finnish market share in 2019). The food category, full product name, type of P additive (inorganic, organic, and natural P-containing), and reporting methods (name or E number) of P additives were recorded. Duplicates and products lacking ingredient information were excluded. Results: The prevalence of P additives was 36% in the final sample (n 5 5,149). Among food categories, the prevalence varied from 4% in dairy-based snacks to 67% in meat products. Altogether 17 different P additives were observed. Inorganic P additives were the most common P additive type, present in 20% of foodstuffs. Natural P-containing additives were observed in 19% and organic P additives in 2% of foodstuffs. The most commonly used P additives were lecithin (E 322), pyrophosphate (E 450), and triphosphate (E 451). E number was used as a reporting method in 49% of foodstuffs, and full name in 44% of foodstuffs. Reporting by E number was particularly common in the products containing inorganic P. Conclusions: The use of P additives is common in the Finnish food supply, indicating the situation in Europe. The high prevalence of inorganic, that is, the most absorbable and potentially most harmful P additives in particular food groups, and their usual reporting only by E numbers can create challenges in CKD dietary counseling. (c) 2021 The Authors. Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Serum parathyroid hormone is related to genetic variation in vitamin D binding protein with respect to total, free, and bioavailable 25-hydroxyvitamin D in middle-aged Caucasians – a cross-sectional study

Peer reviewe

Low free 25-hydroxyvitamin D and high vitamin D binding protein and parathyroid hormone in obese Caucasians. A complex association with bone?

Background Studies have shown altered vitamin D metabolism in obesity. We assessed differences between obese and normal-weight subjects in total, free, and bioavailable 25-hydroxyvitamin D (25(OH) D, 25(OH) D-Free, and 25(OH) D-Bio, respectively), vitamin D binding protein (DBP), parathyroid hormone (PTH) and bone traits. Methods 595 37-47-year-old healthy Finnish men and women stratified by BMI were examined in this cross-sectional study. Background characteristic and intakes of vitamin D and calcium were collected. The concentrations of 25(OH) D, PTH, DBP, albumin and bone turnover markers were determined from blood. 25(OH) D-Free and 25(OH) D-Bio were calculated. pQCT was performed at radius and tibia. Results Mean +/- SE (ANCOVA) 25(OH) D-Free (10.8 +/- 0.6 vs 12.9 +/- 0.4 nmol/L; P = 0.008) and 25(OH) DBio (4.1 +/- 0.3 vs 5.1 +/- 0.1 nmol/L; P = 0.003) were lower in obese than in normal-weight women. In men, 25(OH) D (48.0 +/- 2.4 vs 56.4 +/- 2.0 nmol/L, P = 0.003), 25(OH) D-Free (10.3 +/- 0.7 vs 12.5 +/- 0.6 pmol/L; P = 0.044) and 25(OH) D-Bio (4.2 +/- 0.3 vs 5.1 +/- 0.2 nmol/L; P = 0.032) were lower in obese. Similarly in all subjects, 25(OH) D, 25(OH) D-Free and 25(OH) D-Bio were lower in obese (P Conclusions The associations between BMI and 25(OH) D, 25(OH) D-Free, and 25(OH) D-Bio, DBP, and PTH suggest that obese subjects may differ from normal-weight subjects in vitamin D metabolism. BMI associated positively with trabecular bone traits and CSI in our study, and slightly negatively with cortical bone traits. Surprisingly, there was a negative association of free and bioavailable 25(OH) D and some of the bone traits in obese women.Peer reviewe

Dietary phosphorus intake is negatively associated with bone formation among women and positively associated with some bone traits among men-a cross-sectional study in middle-aged Caucasians

High dietary phosphorus (P) intake has acute negative effects on calcium (Ca) and bone metabolism, but long-term clinical data are contradictory. We hypothesized that high P intake is associated with impaired bone health as suggested by earlier short-term studies on bone metabolism. In this cross-sectional study, we investigated associations between dietary P intake, bone traits in the radius and tibia, and bone turnover in a population-based sample of 37- to 47-year-old Caucasian premenopausal women (n = 333) and men (n = 179) living in Southern Finland (60 degrees N). We used various regression models in an "elaboration approach" to elucidate the role of P intake in bone traits and turnover. The addition of relevant covariates to the models mainly removed the significance of P intake as a determinant of bone traits. In the final regression model (P intake, weight, height, age, Ca intake, serum 25-hydroxyvitamin D, physical activity, smoking, contraceptive use in women), P intake was slightly positively associated only with bone mineral content and cross-sectional cortical bone area in the tibia of men. Among women, inclusion of Ca removed all existing significance in the crude models for any bone trait. In women P intake was negatively associated with the bone formation marker serum intact pro-collagen type I amino-terminal propeptide, whereas no association was present between P intake and bone turnover in men. In conclusion, these findings disagree with the hypothesis; P intake was not deleteriously associated with bone traits; however, P intake may negatively contribute to bone formation among women. (C) 2016 Elsevier Inc. All rights reserved.Peer reviewe

Low free 25-hydroxyvitamin D and high vitamin D binding protein and parathyroid hormone in obese Caucasians. A complex association with bone?

<div><p>Background</p><p>Studies have shown altered vitamin D metabolism in obesity. We assessed differences between obese and normal-weight subjects in total, free, and bioavailable 25-hydroxyvitamin D (25(OH)D, 25(OH)D_Free, and 25(OH)D_Bio, respectively), vitamin D binding protein (DBP), parathyroid hormone (PTH) and bone traits.</p><p>Methods</p><p>595 37-47-year-old healthy Finnish men and women stratified by BMI were examined in this cross-sectional study. Background characteristic and intakes of vitamin D and calcium were collected. The concentrations of 25(OH)D, PTH, DBP, albumin and bone turnover markers were determined from blood. 25(OH)D_Free and 25(OH)D_Bio were calculated. pQCT was performed at radius and tibia.</p><p>Results</p><p>Mean±SE (ANCOVA) 25(OH)D_Free (10.8±0.6 vs 12.9±0.4 nmol/L; P = 0.008) and 25(OH)D_Bio (4.1±0.3 vs 5.1±0.1 nmol/L; P = 0.003) were lower in obese than in normal-weight women. In men, 25(OH)D (48.0±2.4 vs 56.4±2.0 nmol/L, P = 0.003), 25(OH)D_Free (10.3±0.7 vs 12.5±0.6 pmol/L; P = 0.044) and 25(OH)D_Bio (4.2±0.3 vs 5.1±0.2 nmol/L; P = 0.032) were lower in obese. Similarly in all subjects, 25(OH)D, 25(OH)D_Free and 25(OH)D_Bio were lower in obese (P<0.001). DBP (399±12 vs 356±7mg/L, P = 0.008) and PTH (62.2±3.0 vs 53.3±1.9 ng/L; P = 0.045) were higher in obese than in normal-weight women. In all subjects, PTH and DBP were higher in obese (P = 0.047and P = 0.004, respectively). In obese women, 25(OH)D was negatively associated with distal radius trabecular density (R² = 0.089, P = 0.009) and tibial shaft cortical strength index (CSI) (R² = 0.146, P = 0.004). 25(OH)D_Free was negatively associated with distal radius CSI (R² = 0.070, P = 0.049), radial shaft cortical density (CorD) (R² = 0.050, P = 0.045), and tibial shaft CSI (R² = 0.113, P = 0.012). 25(OH)D_Bio was negatively associated with distal radius CSI (R² = 0.072, P = 0.045), radial shaft CorD (R² = 0.059, P = 0.032), and tibial shaft CSI (R² = 0.093, P = 0.024).</p><p>Conclusions</p><p>The associations between BMI and 25(OH)D, 25(OH)D_Free, and 25(OH)D_Bio, DBP, and PTH suggest that obese subjects may differ from normal-weight subjects in vitamin D metabolism. BMI associated positively with trabecular bone traits and CSI in our study, and slightly negatively with cortical bone traits. Surprisingly, there was a negative association of free and bioavailable 25(OH)D and some of the bone traits in obese women.</p></div

Low free 25-hydroxyvitamin D and high vitamin D binding protein and parathyroid hormone in obese Caucasians:a complex association with bone?

Abstract Background: Studies have shown altered vitamin D metabolism in obesity. We assessed differences between obese and normal-weight subjects in total, free, and bioavailable 25-hydroxyvitamin D (25(OH)D, 25(OH)DFree, and 25(OH)DBio, respectively), vitamin D binding protein (DBP), parathyroid hormone (PTH) and bone traits. Methods: 595 37–47-year-old healthy Finnish men and women stratified by BMI were examined in this cross-sectional study. Background characteristic and intakes of vitamin D and calcium were collected. The concentrations of 25(OH)D, PTH, DBP, albumin and bone turnover markers were determined from blood. 25(OH)DFree and 25(OH)DBio were calculated. pQCT was performed at radius and tibia. Results: Mean±SE (ANCOVA) 25(OH)DFree (10.8±0.6 vs 12.9±0.4 nmol/L; P = 0.008) and 25(OH)DBio (4.1±0.3 vs 5.1±0.1 nmol/L; P = 0.003) were lower in obese than in normal-weight women. In men, 25(OH)D (48.0±2.4 vs 56.4±2.0 nmol/L, P = 0.003), 25(OH)DFree (10.3±0.7 vs 12.5±0.6 pmol/L; P = 0.044) and 25(OH)DBio (4.2±0.3 vs 5.1±0.2 nmol/L; P = 0.032) were lower in obese. Similarly in all subjects, 25(OH)D, 25(OH)DFree and 25(OH)DBio were lower in obese (P&lt;0.001). DBP (399±12 vs 356±7mg/L, P = 0.008) and PTH (62.2±3.0 vs 53.3±1.9 ng/L; P = 0.045) were higher in obese than in normal-weight women. In all subjects, PTH and DBP were higher in obese (P = 0.047and P = 0.004, respectively). In obese women, 25(OH)D was negatively associated with distal radius trabecular density (R²2 = 0.089, P = 0.009) and tibial shaft cortical strength index (CSI) (R² = 0.146, P = 0.004). 25(OH)DFree was negatively associated with distal radius CSI (R² = 0.070, P = 0.049), radial shaft cortical density (CorD) (R² = 0.050, P = 0.045), and tibial shaft CSI (R² = 0.113, P = 0.012). 25(OH)DBio was negatively associated with distal radius CSI (R² = 0.072, P = 0.045), radial shaft CorD (R² = 0.059, P = 0.032), and tibial shaft CSI (R² = 0.093, P = 0.024). Conclusions: The associations between BMI and 25(OH)D, 25(OH)DFree, and 25(OH)DBio, DBP, and PTH suggest that obese subjects may differ from normal-weight subjects in vitamin D metabolism. BMI associated positively with trabecular bone traits and CSI in our study, and slightly negatively with cortical bone traits. Surprisingly, there was a negative association of free and bioavailable 25(OH)D and some of the bone traits in obese women

Differences in total (A), free (B) and bioavailable 25(OH)D (C), PTH (D) and DBP (E) concentrations between normal weight, overweight and obese women, men and both sexes combined.

<p>Results are shown for mean (±SE). The values were adjusted for vitamin D intake, age, and holidays in sunny locations (A,B,C), calcium intake (D) or hormonal contraceptives (E). ANCOVA, Bonferroni pairwise comparisons between normal-weight and obese: *P<0.05,**P<0.01,***<0.001, respectively.</p

Characteristics of the subjects stratified by sex and BMI.

<p>Characteristics of the subjects stratified by sex and BMI.</p