Reduced phosphorus intake throughout gestation and lactation of sows is mitigated by transcriptional adaptations in kidney and intestine.

BACKGROUND: The environmental impact of pig farming need to be reduced, with phosphorus (P) being of particular interest. Specified dietary regimens and management systems contribute to meet environmental concerns and reduce economic constrains. However, pregnant and lactating sows represent vulnerable individuals, whose reproductive potential and metabolic health status relies on adequate supply of macro- and micronutrients. The aim of this study was to investigate, whether sows fed with a dietary P content that is below or above current recommendations are capable to maintain mineral homeostasis during the reproduction cycle and which endogenous mechanisms are retrieved therefore in kidney and jejunum. Nulliparous gilts were fed iso-energetic diets with recommended (M), reduced (L), or high (H) amounts of mineral P supplements throughout gestation and lactation periods. Blood metabolites and hormones referring to the P homeostasis were retrieved prior to term (110 days of gestation) and at weaning (28 days of lactation). Transcriptional responses in kidney cortex and jejunal mucosa were analyzed using RNA sequencing. RESULTS: The variable dietary P content neither led to an aberration on fertility traits such as total weaned piglets nor to an effect on the weight pattern throughout gestation and lactation. Serum parameters revealed a maintained P homeostasis as reflected by unaltered inorganic P and calcium levels in L and H fed groups. The serum calcitriol levels were increased in lactating L sows. The endocrine responses to the dietary challenge were reflected at the transcriptional level. L diets led to an increase in CYP27B1 expression in the kidney compared to the H group and to an altered gene expression associated with lipid metabolism in the kidney and immune response in the jejunum. CONCLUSIONS: Our results suggest that current P requirements for gestating and lactating sows are sufficient and over supplementation of mineral P is not required. Shifts in renal and jejunal expression patterns between L and H groups indicate an affected intermediate metabolism, which long-term relevance needs to be further clarified.

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.

[Dietary reference intakes of phosphorus].

Phosphorus (P) exists at the all organs and plays important physiological roles in the body. A wide range of food contains P, which is absorbed at a higher level (60-70%) and its insufficiency and deficiency are rarely found. P is used as food additives in many processed food, where risk of overconsumption could be an issue. P has less evidence in terms of nutrition. P has the adequate intake and the tolerable upper intake level, for risk reduction of health disorders associated with excess intake, at the Dietary Reference Intakes for Japanese (2010 edition).

Digestible phosphorus needs of terminal-cross growing-finishing pigs.

Growth and digestion experiments were conducted to estimate the digestible P needs of terminal-cross growing-finishing pigs fed sorghum-soybean meal-based diets from 25 to 118 kg. Dietary available P levels approximated the levels recommended by the NRC (1988) or were approximately 25% above or below those levels. Up to 80 kg, dietary treatment did not affect performance; from 80 to 118 kg, the lowest P level (no inorganic P) reduced (P = .03) feed efficiency. Carcass leanness, subjective quality scores for the loin, chemical content of lean, and sensory evaluation of cooked lean were not adversely affected by decreasing P. As dietary P decreased, connective tissue amount in the lean decreased (P = .06). Ash content (P < .01) and peak load (P < .05) of metacarpals and metatarsals decreased as dietary P decreased, but structural soundness scores in the live pig were unaffected by treatment. Apparent digestibility of P decreased (P = .08 to P < .01) as dietary P decreased in the diets. Estimated P excretions per pig decreased with decreasing dietary P up to 80 kg; during the 80-to-118-kg interval, P excretions were similar for pigs fed the two lowest P diets due to reduced feed efficiency of pigs fed the lowest P diet. Dietary digestible P contents maximizing performance and carcass merit were .21, .19, and .16% for pigs fed from 25 to 50, 50 to 80, and 80 to 118 kg, respectively. The results suggest that P excretions of terminal-cross pigs can be reduced by feeding less than current NRC recommendations for P without reducing performance, carcass merit, or structural soundness of live pigs.

Benefits of calcitriol therapy and serum phosphorus control in dogs and cats with chronic renal failure. Both are essential to prevent of suppress toxic hyperparathyroidism.

Daily oral calcitriol at low doses is safe and effective in the control of renal secondary hyperparathyroidism in dogs and cats. Low doses of calcitriol are most effective when started early in uremia before the advanced stages of renal secondary hyperparathyroidism. At early stages calcitriol both diminishes PTH synthesis in the parathyroid cells present and prevents the hyperplasia that, if unchecked, results in the most extensive an difficult-to-control hyperparathyroidism. The salutary effects on the dog's or cat's sense of well being, appetite, activity, strength, and lifespan as reported by the veterinarians of our survey are attributed primarily to keeping PTH levels below a toxic threshold. Additionally, some of the benefits achieved by calcitriol are likely a direct consequence of calcitriol interacting with the vitamin D receptor in a wide variety of tissues throughout the body. Phosphorus restriction through a combination of diet and intestinal phosphate binders is important to allow calcitriol therapy to successfully lower PTH levels, but it likely has no direct effects that are independent of interactions involving calcitriol. Phosphorus restriction is also important to minimize chances for adverse tissue mineralization. Calcitriol therapy can be considered for treatment of chronic renal failure after serum phosphorus has been decreased to less than 6.0 mg/dL in patients in whom it was initially elevated. Calcitriol supplementation to dogs and cats with chronic renal failure makes good endocrinologic sense. Calcitriol deficits cause increased PTH and, as these two hormones are designed to maintain calcium and phosphorus homeostasis, the PTH increase is initially adaptive. One of the important effects of PTH is to stimulate additional calcitriol formation as a powerful means to raise blood calcium through increased calcium absorption from the diet. With too great an increase in PTH, however, its effects become harmful to many tissues due to the widespread distribution of the PTH receptor in many cell types that are likely normally responsive only to the paracrine PTH-related peptide that shares the PTH receptor. Exogenous supplemental calcitriol administration allows concentrations of calcitriol in the bloodstream to remain normal without the toxic consequences of excessive PTH secretion that would otherwise be provoked. Studies involving young dogs with subtotal nephrectomy may not parallel those on older dogs and cats with spontaneous chronic renal failure. In particular, higher doses are needed to effect PTH change in these young dogs than we have found necessary for older dogs and cats. Because survey participants agreed most strongly with the idea that their calcitriol-treated dogs and cats were living longer than comparably uremic animals they had treated previously, further studies to evaluate the ability of calcitriol to retard the progression of renal lesions and loss of excretory renal function seem warranted. Additional studies to document the beneficial effects of calcitriol on the many organs adversely affected by excess PTH during uremia are also needed because findings thoroughly documented and proven in humans and rats may not always extrapolate to dogs and cats.

Reduced dietary phosphorus levels for layers.

Two experiments were undertaken to study the response of White Leghorn hens to low dietary phosphorus levels from 18 to 64 wk of age. A corn-soybean meal diet containing .2% available phosphorus gave similar performance, up to 32 wk of age, as a similar control diet containing .4% available phosphorus. Beyond 32 wk, although shell quality and average egg weight were similar, egg production was significantly reduced with the lower phosphorus diet. Phosphorus excretion (grams per bird per day) averaged .47 g for .4% vs .28 g for .2% available phosphorus when measured at 28 wk of age. In a second experiment identical procedures and bird number as used in Experiment 1 were employed with the exception that the test diet contained .3% rather than .2% available phosphorus. No differences were noted for any of the production variables measured between the .4 and .3% available phosphorus diets. Phosphorus excretion data collected at 25, 32, 44, and 60 wk of age showed a decrease of approximately 20% for hens receiving the lower phosphorus diet. Indeed the overall average for phosphorus excretion for the lower phosphorus diet was calculated to be identical to the 20% lower total phosphorus content of this diet (.59 vs .47%).

Nutrition intervention program of the Modification of Diet in Renal Disease Study: a self-management approach.

OBJECTIVE: To characterize the Modification of Diet in Renal Disease (MDRD) Study nutrition intervention program by determining the frequency of intervention strategies used by the dietitians and the usefulness of program components as rated by participants. DESIGN: Dietitians recorded which of 32 intervention strategies they used at each monthly visit. Participants rated the usefulness of 19 program components. SUBJECTS: 840 adults with renal insufficiency. INTERVENTION: Participants were assigned randomly to usual-, low-, or very-low-protein diet groups. Each eating pattern also specified a phosphorus intake goal. Each participant met monthly with a dietitian for an average of 26 months. STATISTICAL ANALYSES: Analyses of variance and chi 2 analyses. RESULTS: Dietitians used the following intervention strategies most often in all groups: providing feedback based on self-monitoring and/or food records, reviewing adherence or biochemistry data, providing low-protein foods, and reviewing graphs of adherence progress. In general, the dietitians used feedback, modeling, and support strategies more often, and knowledge and skills strategies less often, with participants who had to make the greatest reductions in protein intake and those with more advanced disease. In all groups, the dietitians' use of knowledge and skills, feedback, and modeling strategies decreased over time (P < .001), whereas use of support strategies was maintained. The type and frequency of intervention strategies used by dietitians and the usefulness ratings of participants did not vary by educational level of the participant. Both self-monitoring and dietitian support were rated as "very useful" by 88% of the participants. CONCLUSIONS: Three features were central to the MDRD Study nutrition intervention program: feedback, particularly from self-monitoring and from measures of adherence; modeling, particularly by providing low-protein food products; and dietitian support. We recommend the self-management approach.

Factors associated with adherence to the dietary protein intervention in the Modification of Diet in Renal Disease Study.

OBJECTIVE: To determine the characteristics and behaviors associated with adherence to dietary protein interventions among participants with chronic renal disease in the Modification of Diet in Renal Disease (MDRD) Study. DESIGN: Participants were categorized as consistent adherers or nonadherers on the basis of urinary urea nitrogen excretion and dietary protein intake data from self-reports. Psychosocial and behavioral factors were compared between groups. SUBJECTS: Subgroups of consistently adherent and non-adherent participants in the MDRD Study. SETTING: 15 clinical centers in the United States. INTERVENTION: In the nutrition intervention program, participants were assigned randomly to a usual-, low-, or very-low-protein diet group. Each eating pattern also specified a phosphorus goal. STATISTICAL ANALYSIS: Analysis of variance. RESULT: Psychosocial factors significantly related to adherence included participant knowledge, attitude, support, satisfaction, and self-perception of success. Behavioral strategies including participant self-monitoring of protein intake and the provision of feedback by the dietitian were also significantly related to adherence. APPLICATION: Nutrition interventions for patients with renal disease should focus on psychosocial factors and behavioral approaches. Such approaches can be successfully incorporated into treatment programs and will assist the dietitian in promoting adherence to usual-, low-, and very-low-protein eating patterns.