title: Vitamin-D status is not a confounder of the relationship between zinc and diarrhoea: a study in 6-24-month-old underweight and normal-weight children of urban Bangladesh.
abstract: The role of micronutrients particularly zinc in childhood diarrhoea is well established. Immunomodulatory functions of vitamin-D in diarrhoea and its role in the effect of other micronutrients are not well understood. This study aimed to investigate whether vitamin-D directly associated or confounded the association between other micronutrient status and diarrhoeal incidence and severity in 6-24-month underweight and normal-weight children in urban Bangladesh.
  
  
  
  Multivariable generalised estimating equations were used to estimate incidence rate ratios for incidence (Poisson) and severity (binomial) of diarrhoea on cohorts of 446 normal-weight and 466 underweight children. Outcomes of interest included incidence and severity of diarrhoea, measured daily during a follow-up period of 5 months. The exposure of interest was vitamin-D status at enrolment.
  
  
  
  Normal-weight and underweight children contributed 62 117 and 62 967 day observation, with 14.2 and 12.8 days/child/year of diarrhoea, respectively. None of the models showed significant associations of vitamin-D status with diarrhoeal morbidity. In the final model, zinc-insufficient normal-weight children had 1.3 times more days of diarrhoea than sufficient children (P<0.05). Again zinc insufficiency and mother's education (1-5 and >5 years) had 1.8 and 2.3 times more risk of severe diarrhoea. In underweight children, older age and female had 24-63 and 17% fewer days of diarrhoea and 52-54 and 31% fewer chances of severe diarrhoea.
  
  
  
  Vitamin-D status was not associated with incidence and severity of diarrhoea in study children. Role of zinc in diarrhoea was only evident in normal-weight children. Our findings demonstrate that vitamin-D is not a confounder of the relationship between zinc and diarrhoea.
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, QLD, Australia.|Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: A M S
authors.initials: AM
authors.lastname: Ahmed
authors.affiliation: School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia.|Child Health Research Centre, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: R J S
authors.initials: RJ
authors.lastname: Magalhaes
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: T
authors.initials: T
authors.lastname: Ahmed
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, QLD, Australia.|Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.
authors.forename: K Z
authors.initials: KZ
authors.lastname: Long
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: MdI
authors.initials: M
authors.lastname: Hossain
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: M M
authors.initials: MM
authors.lastname: Islam
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: M
authors.initials: M
authors.lastname: Mahfuz
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: S M A
authors.initials: SM
authors.lastname: Gaffar
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: A
authors.initials: A
authors.lastname: Sharmeen
authors.affiliation: Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: R
authors.initials: R
authors.lastname: Haque
authors.affiliation: Division of Infectious Diseases and International Health, Department of Internal Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Guerrant
authors.affiliation: Division of Infectious Diseases and International Health, Department of Internal Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Petri
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, QLD, Australia.|Centre for Nutrition and Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: A A
authors.initials: AA
authors.lastname: Mamun
mesh_terms: D001459:Bangladesh / Q000453:epidemiology; D002675:Child, Preschool; D003967:Diarrhea / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D056865:Ideal Body Weight / Q000502:physiology*; D015994:Incidence; D007223:Infant; D008297:Male; D015999:Multivariate Analysis; D016012:Poisson Distribution; D012720:Severity of Illness Index; D013851:Thinness / Q000097:blood* / Q000150:complications; D014505:Urban Population; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000209:etiology; D015032:Zinc / Q000097:blood* / Q000172:deficiency
chemical_list: D014807:Vitamin D; D015032:Zinc