Red Meat Raises Gestational Diabetes Risk, Nuts Lower It

Red meat consumption significantly raises the risk for developing gestational diabetes mellitus (GDM), while eating nuts reduces it, new data from the Nurses' Health Study II suggest.

The findings were published online February 1 in Diabetes Care by Wei Bao, MD, PhD, an epidemiologist with the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland, and colleagues.

They analyzed prepregnancy food questionnaires for 15,294 women with a total of 21,457 singleton pregnancies, including 870 in which a first-time diagnosis of GDM was made.

After adjustment for age, parity, body mass index (BMI), dietary factors — including fat and cholesterol intake — and other covariates, greater consumption of animal protein was associated with significantly increased GDM risk, while higher vegetable protein intake was associated with significantly reduced risk.

Dr. Bao and colleagues say red meat consumption has been associated with an increased risk for GDM in a prior study, but the relationship between nut and legume intake and gestational diabetes hadn't previously been evaluated, nor had the links between eating other major sources of protein (poultry, fish, and dairy products) and likelihood of GDM.

"Our findings suggest that among women of reproductive age, substitution of vegetable protein for animal protein, as well as substitution of some healthy protein sources (eg, nuts, legumes, poultry, and fish) for red meat may potentially lower GDM risk," they state.

Eating More vs Less Red Meat Doubles Risk for GDM

Comparing highest vs lowest quintiles, the researchers determined that the multivariate risk ratios for developing GDM were 1.28 for total protein intake, 1.49 for animal protein, and 0.69 for vegetable protein.

The authors calculated that substituting 5% of energy intake from carbohydrates with animal protein was associated with a 29% increase in GDM risk (P = .006). On the other hand, switching 5% of energy from animal protein to vegetable protein would result in a 51% lower GDM risk (P = .009).

Prepregnancy BMI explained about a third of the effect of total protein and animal protein on GDM risk but did not have an impact on the relationship between vegetable protein and GDM.

Eating red meat in particular appeared most detrimental. Relative risks for GDM for the highest compared with the lowest quintile of red meat consumption were 2.05 for total red meat, 1.60 for unprocessed red meat, and 1.36 for processed red meat after adjustments, including for BMI.

In contrast, prepregnancy consumption of nuts was associated with a significantly lower risk for GDM, with a risk ratio of 0.73 for highest vs lowest quintile after adjustments.

Substituting 1 serving per day of total red meat with a more healthful protein source was associated with a 29% lower risk for GDM for poultry, 33% for fish, 51% for nuts, and 33% for legumes.

Previous studies have suggested that high-protein diets can adversely affect glucose homeostasis, the researchers say.

Meat consumption in particular has been found to be associated with long-term weight gain, type 2 diabetes, coronary artery disease, stroke, and all-cause mortality.

Nuts, on the other hand, are a good source of vegetable protein, are rich in mono- and polyunsaturated fats, fiber, and magnesium, and have a low glycemic index, all of which have been associated with improved insulin sensitivity and a reduced risk for type 2 diabetes.

This study was funded by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health. The Nurses' Health Study II was funded by research grants from the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Diabetes Care. Published online February 1, 2013. Abstract