Letters Pre-pregnancy potato consumption and gestational diabetes

Authors’ reply to Gachi, Mullie and colleagues, and Weatherburn

BMJ 2016; 352 doi: https://doi.org/10.1136/bmj.i1191 (Published 02 March 2016) Cite this as: BMJ 2016;352:i1191
  1. Cuilin Zhang, senior investigator1,
  2. Wei Bao, assistant professor1,
  3. Deirdre K Tobias, instructor2 3,
  4. Jorge E Chavarro, associate professor3 4 5,
  5. Frank B Hu, professor3 4 5
  1. 1Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20852, USA
  2. 2Division of Preventive Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02215, USA
  3. 3Department of Nutrition, Harvard T H Chan School of Public Health, Boston, MA 02115, USA
  4. 4Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, MA 02115, USA
  5. 5Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
  1. zhangcu{at}mail.nih.gov

We appreciate the interest in our recent article on pre-pregnancy potato consumption and risk of gestational diabetes mellitus (GDM).1 Below we provide responses to a few major points raised by readers

Sweet potato and GDM risk

Pre-pregnancy consumption of potato in our study did not include sweet potato.2 Sweet potato consumption in our study population was too low (~95% consumed <1 serving a week) for us to reliably evaluate its association with the risk of GDM. The role of pre-pregnancy sweet potato consumption in the development of GDM warrants further investigation. We are aware that sweet potato—which is rich in complex carbohydrates, dietary fibre, β carotene, vitamin C, vitamin B6, anthocyanin, and minerals—is considered to be a nutritious vegetable.3 Studies in animal models indicated that sweet potatoes have hypoglycaemic effects through ameliorating oxidative stress and inflammation and improving pancreatic β cells mass.4 In humans, sweet potato has been used in traditional medicine for the treatment of type 2 diabetes. However, data from randomised controlled trials and large observational studied on the efficacy of sweet potato in glycaemic control in humans are insufficient and inconclusive.3

Potato, glycaemic index, and GDM

Our study was not designed to look at the underlying mechanisms of the observed positive association between pre-pregnancy potato intake and GDM risk; future studies will elucidate these.5 Evidence suggests that the potato’s high glycaemic index …

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