Pre-pregnancy potato consumption and risk of gestational diabetes mellitus: prospective cohort studyBMJ 2016; 352 doi: https://doi.org/10.1136/bmj.h6898 (Published 12 January 2016) Cite this as: BMJ 2016;352:h6898
- Wei Bao, postdoctoral fellow1,
- Deirdre K Tobias, instructor2 3,
- Frank B Hu, professor3 4 5,
- Jorge E Chavarro, associate professor3 4 5,
- Cuilin Zhang, senior investigator1
- 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
- 2Division of Preventive Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02215, USA
- 3Department of Nutrition, Harvard T H Chan School of Public Health, Boston, MA 02115, USA
- 4Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, MA 02115, USA
- 5Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Correspondence to: C Zhang
- Accepted 3 December 2015
Study question What is the association between potato consumption before pregnancy and the risk of gestational diabetes mellitus (GDM)?
Methods This prospective cohort study included 15 632 women from the Nurses’ Health Study II (1991-2001). They had no previous GDM or chronic diseases before pregnancy. Consumption of potatoes and other foods was assessed every four years. Incident first time GDM was ascertained from self reports of a physician diagnosis of GDM, which was previously validated by medical records.
Study answer and limitations Over the 10 year follow-up there were 854 incident cases of GDM among 21 693 singleton pregnancies. After adjustment for age, parity, and dietary and non-dietary factors, women who consumed more potatoes before pregnancy had higher rates of developing GDM. Substitution of two servings a week of total potatoes with other vegetables, legumes, and whole grain foods was significantly associated with a 9-12% lower risk of GDM. Consumption and diabetes were self reported, and severity of diabetes was unknown. More than 90% of women were white. A causal association cannot be assumed.
What this paper adds Higher levels of potato consumption before pregnancy are associated with greater risk of GDM, and substitution of potatoes with other vegetables, legumes, or whole grain foods might lower the risk.
Funding, competing interests, data sharing Funding was received from the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institutes of Health, and the American Diabetes Association (No 7-12-MN-34). The authors have no competing interests or additional data to share.
Contributors: WB and CZ contributed to the study design. JEC and FBH were involved in data collection. WB analyzed the data and drafted the manuscript. DKT conducted technical review. All authors contributed to the interpretation of the results and revision of the manuscript for important intellectual content and approved the final version of the manuscript. WB and CZ are guarantors.
Funding: This study was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract No HHSN275201000020C). The Nurses’ Health Study II was funded by research grants DK58845, CA50385, P30 DK46200, and UM1 CA176726 from the National Institutes of Health. DKT and FBH were supported by a mentored fellowship from the American Diabetes Association (No 7-12-MN-34).
Competing interest: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: The study protocol was approved by the Partners Human Research Committee (Boston, MA, USA). The completion of the self administered questionnaire was considered to imply informed consent.
Transparency: The senior author, CZ, affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted.
Data sharing: No additional data available.
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