title: Day-to-day variations in iron, zinc and copper in breast milk of Guatemalan mothers.
abstract: OBJECTIVE
  To assess the within-subject and between-subject coefficients of variation (CV) of iron, zinc and copper concentrations in the milk of Guatemalan mothers.
  
  
  METHODS
  We performed a cross-sectional study in lactating women who had delivered a healthy infant 1 to 6 months previously in two low-income peri-urban areas (San Bartolome Milpas Altas and Ciudad Peronia) and a low-income rural area (San Juan Chamelco) in Guatemala. Women infested with Ascaris lumbricoides or Trichuris trichiura received a single dose of albendazole (400 mg) or placebo. Two weeks after treatment, milk samples were collected on 3 or 4 consecutive days. Trace element concentrations in milk were measured by inductively coupled plasma/atomic emission spectrometry.
  
  
  RESULTS
  The instrumental error of the inductively coupled plasma/atomic emission spectrometry method, expressed as SD, was 0.04, 0.27 and 0.02 mg/L for iron, zinc and copper, respectively. Concentrations in milk samples collected from 47 mothers on 3 or 4 consecutive days, expressed as mean +/- SD, were 0.28 +/- 0.13, 2.03 +/- 0.37 and 0.29 +/- 0.07 mg/L for iron, zinc and copper, respectively. The within-subject CV was 46.1%, 18.2%, and 22.8% and the between-subject CV was 61.2%, 48.3% and 31.7% for iron, zinc and copper, respectively. Stage of lactation, infestation with intestinal parasites and residential area had a significant influence on milk zinc, copper and iron concentrations.
  
  
  CONCLUSIONS
  One sample of milk is sufficient to give a reliable estimate of the zinc concentration in milk. Two samples taken on consecutive days are required for a reliable estimate of iron and copper concentrations.
authors.affiliation: Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands. rosalierutten@yahoo.com
authors.forename: Rosalie A M
authors.initials: RA
authors.lastname: Dhonukshe-Rutten
authors.forename: Marieke
authors.initials: M
authors.lastname: Vossenaar
authors.forename: Clive E
authors.initials: CE
authors.lastname: West
authors.forename: Klaus
authors.initials: K
authors.lastname: Schümann
authors.forename: Jesus
authors.initials: J
authors.lastname: Bulux
authors.forename: Noel W
authors.initials: NW
authors.lastname: Solomons
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002940:Circadian Rhythm; D003300:Copper / Q000032:analysis*; D003430:Cross-Sectional Studies; D005260:Female; D006166:Guatemala; D006801:Humans; D007223:Infant; D007227:Infant Nutritional Physiological Phenomena; D007231:Infant, Newborn; D007411:Intestinal Diseases, Parasitic / Q000150:complications / Q000378:metabolism; D007501:Iron / Q000032:analysis*; D007774:Lactation / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry*; D012424:Rural Population / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic / Q000379:methods*; D014505:Urban Population / Q000706:statistics & numerical data; D015032:Zinc / Q000032:analysis*
chemical_list: D003300:Copper; D007501:Iron; D015032:Zinc