The role of energy, nutrients, foods and dietary patterns in the development of gestational diabetes mellitus: a systematic review of observational studies

OBJECTIVE Diet may influence the risk of gestational diabetes mellitus (GDM), but inconsistent findings have been reported. The purpose of this study was to synthesize evidence from observational studies on the associations between dietary factors and GDM. RESEARCH DESIGN AND METHODS Medline and Embase were searched for articles published until January 2015. We included observational studies of reproductive-aged women that reported on associations of maternal dietary intake before or during pregnancy, including energy, nutrients, foods, and dietary patterns, with GDM. All relevant results were extracted from each article. The number of comparable studies that adjusted for confounders was insufficient to perform a meta-analysis. RESULTS The systematic review included 34 articles comprising 21 individual studies (10 prospective cohort, 6 cross-sectional, and 5 case-control). A limited number of prospective cohort studies adjusting for confounders indicated associations with a higher risk of GDM for replacing 1–5% of energy from carbohydrates with fat and for high consumption of cholesterol (≥300 mg/day), heme iron (≥1.1 mg/day), red and processed meat (increment of 1 serving/day), and eggs (≥7 per week). A dietary pattern rich in fruit, vegetables, whole grains, and fish and low in red and processed meat, refined grains, and high-fat dairy was found to be beneficial. The current evidence is based on a limited number of studies that are heterogeneous in design, exposure, and outcome measures. CONCLUSIONS The findings support current dietary guidelines to limit consumption of foods containing saturated fat and cholesterol, such as processed meat and eggs, as part of an overall balanced diet. Further large prospective studies are warranted.