A new study recently published in the BMJ provides evidence that high gluten consumption during pregnancy is associated with a higher risk of offspring developing type 1 diabetes. In a study spanning over twenty years, a team of researchers based in Denmark examined the rate of gluten consumption by mothers during pregnancy and tracked the development of type-1 diabetes in the offspring.
The researchers found that the risk of developing type-1 diabetes in offspring increased proportionally with daily amounts of gluten consumed, with children born from mothers who consumed the highest amounts gluten having almost double the risk of developing type-1 diabetes.
The study is one of the largest of its kind and highlights a potential link between gluten intake and diabetes. However, the researchers are clear to comment that at this point, it is too early to translate their results into specific dietary recommendations, as cutting gluten out of one’s diet could lead to complications due to a lack of other essential vitamins such as B12, calcium or zinc.
Diabetes And Modern Diets
Gluten is a kind of protein found most predominantly in wheat, barley, and rye. It is favored for its viscous-elastic properties and is used to give bread its doughy and fluffy texture. It is well known that in a small subset of the population, gluten intake can trigger serious autoimmune responses, as is the case with coeliac disease and dermatitis herpetiformis. Less well understood are the effects of long-term habitual gluten intake on patients who do not have gluten-related disorders.
The incidence rate of type one diabetes in western countries is the highest in the world, with previous data showing the number of cases growing by 3-4% annually. Given these trends, medical practitioners infer that the increase in rates of diabetes is due to the typical diet of a person living in industrialized western countries, a diet that is high in wheat products that contain gluten.
Previous studies have shown the effect that high gluten diets have on the incidence rate of diabetes in mice populations. Studies have shown that gluten-free diets in mice can lower the incidence rate of diabetes from 64% to 15% and that pregnant mice fed a gluten-free diet showed a decrease in the incidence rate of diabetes in offspring from 64% to 8%. Additionally, the same genes that are implicated in coeliac disease are also implicated in the development of type-1 diabetes. The current study is an attempt to link these laboratory findings to human populations and human diets.
The study examines 67,565 pregnancies, tracking the mother’s gluten intake during pregnancy and examines the rate of diabetes in those pregnancies over a period of twenty years. Once the subjects were selected, at 25 weeks of pregnancy each participant was asked to fill out a 360 item questionnaire on daily food intake; questions related to the composition of their diets or how often they eat products containing wheat, barley, or rye. The researchers then tracked the development of type 1 diabetes in the offspring of the participants over a 20 year time period, making note of how early or late the condition developed.
Preliminary results showed that the average gluten intake for the participants sits at 13g per day and the overall number of diabetes diagnoses was 247, corresponding to a 0.37 incidence rate. The average age of the onset of the condition was found to be 15.6 years. The data showed a significant positive association between maternal gluten intake and increase risk of diabetes in offspring. Compared to offspring from mothers with the lowest percentile gluten intake (<7g per day), offspring from mothers with the highest gluten intake (>20g per day) had almost double the risk of developing diabetes, with a 95% interval of confidence. The association between maternal gluten intake and the onset of diabetes in offspring was most pronounced in older subjects (>30 years) and those who were previously overweight or obese during pregnancy. Additionally, this association was most pronounced in male offspring.
The study was one of the largest of its kind, meaning the data is robust enough to see clear statistical associations. Despite this, the study does have some limitations. Perhaps most obviously, it does not provide an account of the physiological mechanism that explains the relation between gluten intake and diabetes. It is suggested that overexposure to gluten in the intrauterine environment can negatively affect the development of the immune system, causing it to attack other healthy cells. As with any study that relies on self-response surveys, it is possible that some subjects inaccurately reported their dietary habits or some other ambiguity in the questionnaire led them to give an incorrect response. It also is unable to account for any additional gluten that is intentionally added to foodstuffs post-processing.
Additionally, the study did not gather data on post-delivery infant diets, which is thought to have an effect on the development of diabetes. However, animal experiments show that a gluten-free diet during pregnancy is more effective at preventing diabetes than simply a gluten-free diet indicating that intrauterine development could be the decisive factor for the development of type 1 diabetes.
The researchers are clear that the results of this particular study do not carry any obvious implications or directives for policy. firstly, the associations could vary geographically. The current study was performed on a cohort of Danish women, and the composition of gluten in foodstuff most common in Denmark could be different than gluten produced elsewhere. Also, gluten intake is most likely just one factor that contributes to the development of diabetes. The development of a child’s immune system is dependent on a number of intrauterine factors that are difficult to completely control for. The researchers say that it is too early to translate their findings into dietary recommendations, and that independent confirmation of their findings in a similar study is needed. However, as it stands, these results seem to suggest that a high gluten diet during pregnancy can increase the risk of offspring developing type 1 diabetes.