title: Zinc Intake, Zinc Bioavailability and Plasma Zinc in Obese Adolescents with Clinical Insulin Resistance Following Low Energy Diets.
abstract: Zinc has a critical role in metabolism and growth. This study aims to determine the effects of low-energy diets differing in macronutrient composition on zinc intake, estimated zinc bioavailability (phytate:zinc molar ratio) and plasma zinc concentration and associations between zinc status and cardiometabolic markers in obese adolescents with clinical insulin resistance (IR).
  
  
  
  Eighty-seven obese adolescents (10-17 years, body mass index z-score 2.3 ± 0.37) with clinical IR were randomized to a low-energy diet (6.0-8.0 MJ), which was either high carbohydrate or moderate carbohydrate with increased protein. Twenty-four-hour dietary recalls were collected at 6, 9 and 12 weeks. Plasma zinc concentration and cardiometabolic markers were assessed at baseline and 12 weeks.
  
  
  
  Zinc intake did not differ between the 2 diet groups (p = 0.612). The high-carbohydrate group had a higher phytate intake (894 vs. 671 mg, p = 0.018) and phytate:zinc molar ratio (9.4 vs. 7.4, p = 0.009) than the increased-protein group. Plasma zinc concentration did not change from baseline in either of the diet groups, but correlated positively with zinc intake (r = 0.235, p = 0.042) and % energy from protein (r = 0.383, p = 0.001), and inversely with % energy from carbohydrate (r = -0.296, p = 0.010).
  
  
  
  Low energy diets for obese adolescents at risk of diabetes may need increased protein content to optimize zinc bioavailability.
authors.affiliation: The Children's Hospital at Westmead Clinical School, Westmead, Sydney, Australia.
authors.forename: Mandy
authors.initials: M
authors.lastname: Ho
authors.forename: Anne-Louise M
authors.initials: AM
authors.lastname: Heath
authors.forename: Megan
authors.initials: M
authors.lastname: Gow
authors.forename: Louise A
authors.initials: LA
authors.lastname: Baur
authors.forename: Chris T
authors.initials: CT
authors.lastname: Cowell
authors.forename: Samir
authors.initials: S
authors.lastname: Samman
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Garnett
mesh_terms: D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D002648:Child; D002664:Child Nutritional Physiological Phenomena; D003677:Deficiency Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D000070601:Diet, Carbohydrate Loading / Q000009:adverse effects; D000076107:Diet, High-Protein Low-Carbohydrate / Q000009:adverse effects; D018753:Diet, Protein-Restricted / Q000009:adverse effects; D004038:Diet, Reducing / Q000009:adverse effects*; D004043:Dietary Fiber / Q000009:adverse effects; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D007408:Intestinal Absorption; D008297:Male; D009517:New South Wales / Q000453:epidemiology; D050177:Overweight / Q000097:blood / Q000178:diet therapy* / Q000378:metabolism / Q000503:physiopathology; D063766:Pediatric Obesity / Q000097:blood / Q000178:diet therapy* / Q000378:metabolism / Q000503:physiopathology; D012306:Risk; D015032:Zinc / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism / Q000627:therapeutic use*
chemical_list: D015415:Biomarkers; D004043:Dietary Fiber; D015032:Zinc