Researchers in Japan believed they were the first to examine the association between chocolate consumption and GDM.
The findings from the prospective cohort study were published in the British Journal of Nutrition.
Chocolate was previously documented in intervention and observational studies on its beneficial effects on blood pressure, insulin resistance, and type 2 diabetes, but never on GDM.
A total of 84,948 healthy women were recruited over three years, with a median gestational age of 12 weeks.
GDM was diagnosed using oral glucose tolerance test. During the period of pregnancy, 1904 cases of GDM (2.2%) were identified.
The participants dietary intake were assessed using a food frequency questionnaire, and included food and beverage intake during the past 12 months before they were recruited.
The portion size of chocolate was set at 25g. Participants were grouped into four quartiles, with median chocolate consumptions of 0, 11.7, 37.5, and 87.5 g/week.
More chocolate, lower risk
The study found that women in the highest quartile of chocolate consumption, compared with those in the lowest quartile, had a significantly lower risk of developing GDM (p=0.002).
However, researchers said higher chocolate consumption was also related to higher intakes of total meat, red meat, coffee, green tea, soy isoflavone, dietary magnesium, dietary fat, snacks, and total energy.
They added: “Even after controlling for important risk factors, findings from our analyses suggested that higher chocolate consumption was associated with a significant lower risk of GDM.”
According to them, one possible mechanism underlying the inverse association of chocolate consumption with GDM risk may be related to the improvement in insulin resistance.
Several studies in the past have reported an improvement in insulin resistance by cocoa product intervention (e.g., chocolate, cocoa drink) in subjects 24 to 42 years old.
In addition, results from a subsequent trial conducted in 90 elderly individuals showed a significant improvement in homeostasis model assessment for insulin resistance (HOMA-IR), a common insulin resistance index, after 8 weeks of cocoa drink intervention.
Although there was no previous study looking at the chocolate-GDM association, the association between chocolate consumption and risk of type 2 diabetes had been examined in some studies.
A pooled analysis showed that higher chocolate consumption, compared with lower chocolate consumption, was associated with an 18% reduction in risk of type 2 diabetes.
The researchers were aware of several limitations of the study.
“Fat, sugar, and polyphenol contents vary by chocolate types, but data on types of chocolate, as with previous cohort studies on chocolate research, were not available [in this study],
Any comparison on risk of GDM between dark, milk, and white chocolate could not be performed, and whether the observed association was attributed to cocoa polyphenol could not be tested either.”
Although they observed milk chocolate appeared to be the most consumed chocolate in Japan. Sweet pastry and snack bars were not included as chocolate in the study.
The researchers also found that the large sample size could make minuscule differences between groups become statistically significant.
They said, “Our study provided the first evidence that higher chocolate consumption was associated with a lower risk of GDM,” but suggested that further well-designed cohort studies among other populations as well as randomised controlled trials taking GDM as the endpoint could be conducted.
Source: British Journal of Nutrition
“Chocolate consumption and risk of gestational diabetes mellitus: the Japan Environment and Children’s Study”
Authors: Dong J-Y, et al.