Deborah L. O'Connor, Ph.D., R.D.
Professor, Department of Nutritional Sciences
Director, Department of Clinical Dietetics
Senior Associate Scientist, Physiology & Experimental Medicine Program, The Hospital for Sick Children

Ph: 416.813.7844
Fax: 416.813.7849


  • Our research program is focused on two broad areas of maternal and infant nutrition. First, we are interested in understanding the factors that affect the folate status of women, infants and young children. In particular we are investigating the role that bacterial biosynthesis of folate in the colon plays on the folate status of humans. We are in the midst of assessing whether the bacterial milieu can be manipulated by dietary means to improve the nutrition and health of humans. Second, we are studying the impact of feeding nutrient-enriched human milk early after hospital discharge on the growth, body composition and development (mental and motor) of very low birthweight infants during the first 18 months of life.

Selected Publications:                                                   


  • Shakur Y, Garriguet D, Corey P and O’Connor DL.  Folic acid fortification over mandated levels results in a low prevalence of folate inadequacy among Canadians. American Journal of Clinical Nutrition 92(4):818-25, 2010 (Senior responsible author).

  • Tactacan G, Jing M, Thiessen S, Rodriguez-Lecompte JC, O’Connor DL, Guenter W, House J. Characterization of folate-dependent enzymes and indices of folate status in laying hens supplemented with folic acid or 5-methyltetrahydrofolate. Poultry Science 89(4):688-696, 2010. (Collaborator, 10% effort).

  • Obadia M, Rakhshani N, Jeffery AS, Chahal N, Sangha G, McCrindle BW, O’Connor DL, Maccarone T, Hamilton J.  MEALTRAIN:  What do inpatient hospitalized children choose to eat? Journal of Pediatrics 156(4):685-686, 2010. (Collaborator, 5% effort).

  • Khambalia AZ, O’Connor DL, Macarthur C, Depuis A, Zlotkin S: Periconceptional iron supplementation does not reduce anemia or improve iron status among pregnant women in rural Bangladesh. American Journal of Clinical Nutrition 90(5):1295-302, 2009. (Co-principal author).

  • O’Keefe SJ, Ou J, Aufreiter S, O’Connor DL , Sharma S, Sepulveda J, Fukuwatari T, Shibata K, Mawhinney T:  The nutritional role of the microbiota in populations with a high and low risk of colon cancer. Journal of Nutrition 139(11):2044-2048, 2009.  (Collaborator, 15% effort).

  • Aimone A, Connolly B, Chaudhary S, Lugtu J, Martinuzzi F, Pencharz P, O’Connor  DL:  A combination of pH-sensitive caplet coatings may be an effective non-invasive strategy to deliver bioactive substances, nutrients or their precursors to the colon. Applied Physiology, Nutrition, and Metabolism 34:893-900, 2009.  (Senior responsible author).

  • Shakur Y, Rogenstein C, Hartman-Carvan B, Tarasuk V, O’Connor DL:  How much folate is in Canadian fortified products 10 years after mandated fortification? Canadian Journal of Public Health 100(4):281-284, 2009.  (Senior responsible author).

  • Aufreiter S, Gregory JF, Pfeiffer CM, Fazili Z, Kim YI, Marcon N, Kamalaporn P, Pencharz P, O’Connor DL: Folate is absorbed across the colon of adults: evidence from cecal infusion of 13C-labeled [6S]-5-formyltetrahydrofolic acid. American Journal of Clinical Nutrition 90(1):116-123, 2009.  (Senior responsible author).

  • Aimone A, Rovet J, Ward W, Jefferies A, Campbell DM, Asztalos E, Feldman M, Vaughan J, Westall C, Whyte H, O’Connor DL: Growth and body composition of human milk-fed premature infants provided with extra energy and nutrients early after hospital discharge:  one year follow-up. Journal of Pediatric Gastroenterology and Nutrition 49(4):456-466, 2009.  (Senior responsible author).

  • Khambalia A, O’Connor DL, Zlotkin S:  Inadequate iron and folate status among rural Bangladeshi females before their first pregnancy. Journal of Nutrition 139(6):1179-1184, 2009.  (Co-principal author).

  • Tam C, McKenna K, Goh YI, Klieger C, O’Connor DL, Koren G, Einarson A: Periconceptional folic acid supplementation–a new indication for therapeutic drug monitoring. Therapeutic Drug Monitoring 31(3):319-326, 2009.(Collaborator, 20% effort).

  • Nguyen P, Tam C, O’Connor DL, Kapur B, Koren G:  Steady-state folate concentrations achieved with 5 mg versus 1.1 mg folic acid supplementation among women of childbearing age. American Journal of Clinical Nutrition 89(3):844-852, 2009.  (Co-principal author).

  • Houghton LA, Yang J, O’Connor DL:  Unmetabolized folic acid and total folate concentrations in breast milk are unaffected by low-dose folate supplements. American Journal of Clinical Nutrition 89(1):216-20, 2009.  (Senior responsible author).

  • Hartman-Craven B, Christofides A, O'Connor DL, Zlotkin S:  Relative bioavailability of iron and folic acid from a new powdered supplement compared to a traditional tablet in pregnant women. BMC Pregnancy and Childbirth  April 2009 [E-pub ahead of print] July 27 2009; 9(1):33. (Collaborator, 20% effort).

  • Nguyen P, Nava-Ocampo A, Levy A, O'Connor DL, Einarson TR, Koren G: Effect of iron content on the tolerability of prenatal multivitamins in pregnancy? BMC Pregnancy and Childbirth 8(1):17 doi:10.1186/1471-2393-8-17, 2008.  (Collaborator, 15% effort).

  • Nash A, Secker D, Corey M, Dunn M, O’Connor DL: Field testing of the 2006 WHO growth charts from birth to 2 years:  Assessment of hospital under-and over-nutrition rates and the usefulness of BMI.  Journal of Parenteral and Enteral Nutrition 32:145-153, 2008.  (Senior responsible author).

  • O’Connor DL, Khan S, Weishuhn K, Vaughan J, Jefferies A, Campbell DM, Asztalos E, Feldman M, Rovet J, Westall C,  Whyte H: Growth and nutrient intakes of human milk-fed premature infants provided with extra energy and nutrients after hospital discharge:  a pilot randomized controlled trial.  Pediatrics 121(4): 766-776, 2008.  (Principal and senior responsible author).

  • Lenati RF, O’Connor DL, Hebert KC, Farber JM, Pagotto FJ:  Growth and survival of Enterobacter sakazakii in human breast milk with and without fortifiers as compared to powdered infant formula. International Journal of Food Microbiology doi:10.1016/j.ijfoodmicro.2007.11.084, 2008.  (Co-principal author).

  • Houghton LA, Sherwood KL, O’Connor DL:  How well do blood folate concentrations predict dietary folate intakes of lactating women post-folic acid fortification of the food supply? BMC Pregnancy and Childbirth 7:25doi:10.1186/1471-2393-7-25, 2007.  (Senior responsible author).

  • Lindzon G, O’Connor DL:  Folate during reproduction:  The Canadian experience with folic acid fortification.  Nutrition Research and Practice 1(3):163-174, 2007.  (Senior responsible author).

Book Chapters:                                                   


  • O’Connor DL, Houghton LA, Sherwood KL: Nutrition issues during lactation. Handbook of Nutrition and Pregnancy, edited by Lammi-Keefe CJ. The Human Press Inc, Totowa, NJ, pg 257-282, 2008. (Co-prinicipal and senior responsible author).

  • Houghton LA, O’Connor DL: Nutrition during pregnancy and lactation. In:  Optimizing Women’s Health through Nutrition, edited by Thompson LU, Ward W. CRC Press:  Taylor and Francis Group, Boca Raton, pg 65-92, 2008 (Senior responsible author).

  • O’Connor DL, Brennan J, Dello S, Streitenberger L:  Use of nonsterile nutritionals for neonates in-hospital and after hospital discharge:  control measures currently instituted at one tertiary care institution.  In: Enterobacter Sakazakii, edited by  Farber J and Forsythe S., ASM Press, Washington, DC, pg. 187-220, 2008 (Principal and senior responsible author).

  • PubMed