title: The relevance of the colon to zinc nutrition.
abstract: Globally, zinc deficiency is widespread, despite decades of research highlighting its negative effects on health, and in particular upon child health in low-income countries. Apart from inadequate dietary intake of bioavailable zinc, other significant contributors to zinc deficiency include the excessive intestinal loss of endogenously secreted zinc and impairment in small intestinal absorptive function. Such changes are likely to occur in children suffering from environmental (or tropical) enteropathy (EE)-an almost universal condition among inhabitants of developing countries characterized by morphologic and functional changes in the small intestine. Changes to the proximal gut in environmental enteropathy will likely influence the nature and amount of zinc delivered into the large intestine. Consequently, we reviewed the current literature to determine if colonic absorption of endogenous or exogenous (dietary) zinc could contribute to overall zinc nutriture. Whilst we found evidence that significant zinc absorption occurs in the rodent colon, and is favoured when microbially-fermentable carbohydrates (specifically resistant starch) are consumed, it is unclear whether this process occur in humans and/or to what degree. Constraints in study design in the few available studies may well have masked a possible colonic contribution to zinc nutrition. Furthermore these few available human studies have failed to include the actual target population that would benefit, namely infants affected by EE where zinc delivery to the colon may be increased and who are also at risk of zinc deficiency. In conducting this review we have not been able to confirm a colonic contribution to zinc absorption in humans. However, given the observations in rodents and that feeding resistant starch to children is feasible, definitive studies utilising the dual stable isotope method in children with EE should be undertaken.
authors.affiliation: School of Medicine, Flinders University of South Australia, Adelaide 5001, Australia. geetha.gopalsamy@flinders.edu.au.
authors.forename: Geetha Lavaniya
authors.initials: GL
authors.lastname: Gopalsamy
authors.affiliation: School of Medicine, Washington University, St Louis, MO 63110, USA. DAlpers@dom.wustl.edu.
authors.forename: David H
authors.initials: DH
authors.lastname: Alpers
authors.affiliation: School of Medicine, Yale University, New Haven, CT 06520, USA. henry.binder@yale.edu.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Binder
authors.affiliation: CSIRO Food and Nutrition Flagship, Gate 13, Kintore Ave, Adelaide, SA 5000, Australia. cuong.tran@csiro.au.
authors.forename: Cuong D
authors.initials: CD
authors.lastname: Tran
authors.affiliation: SRM Institutes for Medical Science, 1 Jawaharlal Nehru Road, Vadapalani, Chennai 600 026, India. drramakrishna.bs@simshospitals.com.
authors.forename: B S
authors.initials: BS
authors.lastname: Ramakrishna
authors.affiliation: School of Medicine, Flinders University of South Australia, Adelaide 5001, Australia. mrbmrsb1@gmail.com.
authors.forename: Ian
authors.initials: I
authors.lastname: Brown
authors.affiliation: School of Medicine, Washington University, St Louis, MO 63110, USA. manary@kids.wustl.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Manary
authors.affiliation: School of Medicine, Flinders University of South Australia, Adelaide 5001, Australia. elissa.mortimer@flinders.edu.au.
authors.forename: Elissa
authors.initials: E
authors.lastname: Mortimer
authors.affiliation: School of Medicine, Flinders University of South Australia, Adelaide 5001, Australia. graeme.young@flinders.edu.au.
authors.forename: Graeme P
authors.initials: GP
authors.lastname: Young
mesh_terms: D010832:6-Phytase / Q000378:metabolism; D000818:Animals; D001682:Biological Availability; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D006706:Homeostasis; D006801:Humans; D006868:Hydrolysis; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D023421:Models, Animal; D010833:Phytic Acid / Q000378:metabolism; D015032:Zinc / Q000008:administration & dosage* / Q000493:pharmacokinetics
chemical_list: D010833:Phytic Acid; D010832:6-Phytase; D015032:Zinc