title: Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial.
abstract: BACKGROUND
  There is concern that recommending protein-enriched meal replacements as part of a weight management program could lead to changes in biomarkers of liver or renal function and reductions in bone density. This study was designed as a placebo-controlled clinical trial utilizing two isocaloric meal plans utilizing either a high protein-enriched (HP) or a standard protein (SP) meal replacement in an outpatient weight loss program.
  
  
  METHODS
  100 obese men and women over 30 years of age with a body mass index (BMI) between 27 to 40 kg/m2 were randomized to one of two isocaloric weight loss meal plans 1). HP group: providing 2.2 g protein/kg of lean body mass (LBM)/day or 2). SP group: providing 1.1 g protein/kg LBM/day. Meal replacement (MR) was used twice daily (one meal, one snack) for 3 months and then once a day for 9 months. Body weight, lipid profiles, liver function, renal function and bone density were measured at baseline and 12 months.
  
  
  RESULTS
  Seventy subjects completed the study. Both groups lost weight (HP -4.29 ± 5.90 kg vs. SP -4.66 ± 6.91 kg, p < 0.01) and there was no difference in weight loss observed between the groups at one year. There was no significant change noted in liver function [AST (HP -2.07 ± 10.32 U/L, p = 0.28; SP 0.27 ± 6.67 U/L, p = 0.820), ALT (HP -1.03 ± 10.08 U/L, p = 0.34; SP -2.6 ± 12.51 U/L, p = 0.24), bilirubin (HP 0.007 ± 0.33, U/L, p = 0.91; SP 0.07 ± 0.24 U/L, p = 0.120), alkaline phosphatase (HP 2.00 ± 9.07 U/L, p = 0.240; SP -2.12 ± 11.01 U/L, p = 0.280)], renal function [serum creatinine (HP 0.31 ± 1.89 mg/dL, p = 0.380; SP -0.05 ± 0.15 mg/dL, p = 0.060), urea nitrogen (HP 1.33 ± 4.68 mg/dL, p = 0.130; SP -0.24 ± 3.03 mg/dL, p = 0.650), 24 hour urine creatinine clearance (HP -0.02 ± 0.16 mL/min, p = 0.480; SP 1.18 ± 7.53 mL/min, p = 0.400), and calcium excretion (HP -0.41 ± 9.48 mg/24 hours, p = 0.830; SP -0.007 ± 6.76 mg/24 hours, p = 0.990)] or in bone mineral density by DEXA (HP 0.04 ± 0.19 g/cm2, p = 0.210; SP -0.03 ± 0.17 g/cm2, p = 0.320) in either group over one year.
  
  
  CONCLUSIONS
  These studies demonstrate that protein-enriched meals replacements as compared to standard meal replacements recommended for weight management do not have adverse effects on routine measures of liver function, renal function or bone density at one year.
authors.affiliation: Center for Human Nutrition, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA. zli@mednet.ucla.edu
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Li
authors.forename: Leo
authors.initials: L
authors.lastname: Treyzon
authors.forename: Steve
authors.initials: S
authors.lastname: Chen
authors.forename: Eric
authors.initials: E
authors.lastname: Yan
authors.forename: Gail
authors.initials: G
authors.lastname: Thames
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Carpenter
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015519:Bone Density; D004038:Diet, Reducing / Q000009:adverse effects*; D004044:Dietary Proteins / Q000009:adverse effects*; D005260:Female; D005526:Food, Formulated / Q000009:adverse effects* / Q000032:analysis; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008055:Lipids / Q000097:blood; D008099:Liver / Q000503:physiopathology*; D008297:Male; D009765:Obesity / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology; D013997:Time Factors
chemical_list: D015415:Biomarkers; D004044:Dietary Proteins; D008055:Lipids