Effects of dietary phosphate restriction and phosphate binders on FGF23 levels in CKD.

BACKGROUND: Elevated levels of fibroblast growth factor 23 (FGF23) are associated with increased risk of adverse outcomes in patients with CKD. Reducing dietary phosphate intake or absorption may decrease FGF23 levels, but data on the combined effects of dietary phosphate restriction and phosphate binders in CKD are limited. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this 2×2 factorial, single-blinded, placebo-controlled, 3-month study, conducted between July 2009 and March 2012, 39 patients with CKD stages 3 or 4 and normal serum phosphate levels were randomly assigned to one of four groups: ad libitum diet plus lanthanum carbonate (LC) placebo (n=10), 900-mg phosphate diet plus LC placebo (n=10), ad libitum diet plus LC (n=11), or 900-mg phosphate diet plus LC (n=8). The dose of LC was 1000 mg three times daily with meals. Dietary restriction was accomplished with outpatient counseling. The primary end point was change in FGF23 levels from baseline. RESULTS: Compared with ad libitum diet, the 900-mg phosphate diet did not significantly reduce FGF23 levels (diet × time interaction, P=0.05). Compared with placebo, LC alone also did not significantly reduce FGF23 levels (LC × time interaction, P=0.21). However, the dual intervention significantly decreased FGF23 levels throughout the study period (diet × LC × time interaction, P=0.02), resulting in a 35% (95% confidence interval, 8%-62%) reduction by study end. CONCLUSION: The combination of LC plus counseling for a phosphate-restricted diet decreased FGF23 levels in patients with CKD stages 3-4 and normal serum phosphate levels.

Impact of poverty on serum phosphate concentrations in the Third National Health and Nutrition Examination Survey.

OBJECTIVE: Increased serum phosphate is associated with adverse health outcomes. High intake of inexpensive processed and fast foods is common in impoverished communities, and is linked with excessive dietary phosphorus intake and elevated serum phosphate concentrations in chronic kidney disease patients. We examined the impact of socioeconomic status on dietary phosphorus intake and serum phosphate concentrations in the general population. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 14,261 adult participants in the Third National Health and Nutrition Examination Survey. PREDICTORS AND OUTCOMES: Poverty to income ratio (PIR; family income indexed to the federal poverty level) was the primary index of socioeconomic status. Serum phosphate was the primary outcome variable. RESULTS: Although estimated phosphorus intake decreased with decreasing quartiles of PIR (P < .001), serum phosphate was inversely associated with PIR (P = .003). The relationship between lower PIR and higher serum phosphate remained significant after adjustment for demographic, laboratory, and dietary intake characteristics (P = .02). Compared with participants in the highest PIR quartile (income >300% of the federal poverty level), participants in the lowest quartile (income < the federal poverty level) had more than twice the odds of hyperphosphatemia (≥ 4.4 mg/dL) in unadjusted and multivariable-adjusted logistic regression analyses (OR, 2.2; 95% CI, 1.5 to 3.2). CONCLUSIONS: Although lower income was associated with decreased estimated phosphorus intake, increasing poverty was independently linked with increased serum phosphate and higher likelihood of hyperphosphatemia. These findings may indicate that conventional dietary instruments underestimate phosphorus intake, especially among impoverished individuals. Further studies are needed to explore these possibilities.

Nutrient intake and body habitus after spinal cord injury: an analysis by sex and level of injury.

BACKGROUND/OBJECTIVES: To examine nutrient intake and body mass index (BMI) in the spinal cord injury (SCI) population according to level of injury and sex. DESIGN: Cross-sectional study conducted at 2 SCI treatment centers. PARTICIPANTS/METHODS: Seventy-three community-dwelling individuals with C5-T12 ASIA Impairment Scale (AIS) A or B SCI. Subjects were divided into 4 groups: male tetraplegia (N = 24), male paraplegia (N = 37), female tetraplegia (N =1), and female paraplegia (N = 11). Mean age was 38 years; 84% were male; 34% were white, 41% were African American, and 25% were Hispanic. Participants completed a 4-day food log examining habitual diet. Dietary composition was analyzed using Food Processor II v 7.6 software. RESULTS: Excluding the 1 woman with tetraplegia, total calorie intake for the other 3 groups was below observed values for the general population. The female paraplegia group tended to have a lower total calorie intake than the other groups, although macronutrient intake was within the recommended range. The male tetraplegia group, male paraplegia group, and the 1 woman with tetraplegia all had higher than recommended fat intake. Intake of several vitamins, minerals, and macronutrients did not meet recommended levels or were excessively low, whereas sodium and alcohol intake were elevated. Using adjusted BMI tables, 74.0% of individuals with SCI were overweight or obese. CONCLUSIONS: Women with paraplegia tended to maintain healthier diets, reflected by lower caloric and fat intakes, fewer key nutrients falling outside recommended guidelines, and less overweight or obesity. Individuals with tetraplegia tended to take in more calories and had higher BMIs, and using adjusted BMI, the majority of the population was overweight or obese. The majority of people with SCI would benefit from nutritional counseling to prevent emerging secondary conditions as the population with SCI ages.

Nutritional status and behavior in subjects with type 1 diabetes, before and after islet transplantation.

BACKGROUND: To investigate whether changes of nutritional status and behavior are associated with islet transplantation (ITx) and to assess their possible mechanisms. METHODS: In this observational study, 52 subjects with type 1 diabetes, 30 of whom received ITx, underwent nutritional assessments. The study consisted of questionnaires complemented by a dietary intake recording, anthropometric measurements, and body composition analysis. Laboratory tests were also reviewed as part of the follow up. RESULTS: After ITx, significant reductions in body weight (3.7 kg; P<0.0001), body mass index (1.39 kg/m2; P<0.0001), waist circumference (3.96 cm; P=0.006), and fat weight (3.28 kg; P<0.01) were observed. The average consumption of carbohydrate and protein were also lower than pretransplant, together with some micronutrients (vitamins B12 and B6, zinc, and phosphorus). Insulin administration and changes in A1C were not associated with a significant change in anthropometric measurements. Subjects on exenatide after ITx showed significantly lower weight and body mass index than those not taking exenatide. CONCLUSIONS: ITx is associated with modifications in nutritional behavior and status. Drugs and health conditions are likely to be at least in part responsible for these changes, but a voluntary modification of eating habits by the patients also plays a role. Strict monitoring of nutritional parameters, counseling by experts in nutrition, and multivitamin/mineral supplement after ITx could be of benefit to the patients.