B12 deficiency during pregnancy can predispose children to metabolic problems such as type 2 diabetes, according to research presented at the annual meeting of the Society of Endocrinology in Brighton, England. These findings could lead to a review of current vitamin B12 requirements for pregnant women, either through improved diet or supplementation.
Vitamin B12 is found in animal products, including fish, meat, poultry, eggs and milk, meaning that deficiency is more likely in those following a vegan diet.
Previous studies have shown that mothers with low levels of B12 had a higher BMI and were more likely to give birth to babies with low birth weight and high cholesterol levels. These children also had higher insulin resistance in childhood, a risk factor for type 2 diabetes.
In this study, a team of researchers from the University of Warwick Medical School hypothesised that the changes associated with B12 deficiency may be the result of abnormal levels of leptin - the hormone that tells us we are full after eating.
Leptin is mainly produced by the body's fat cells and its levels increase in response to food consumption. Obesity causes an increase in leptin levels. This can lead to leptin resistance, resulting in continued overeating and an increased risk of insulin resistance. Therefore, scientists and doctors see leptin as a predictor of body fat.
Researchers found that babies born to mothers with B12 deficiency had higher than normal leptin levels. This suggests that maternal B12 deficiency may negatively program the leptin gene, altering the levels at which the hormone is produced as the fetus grows.
«The nutritional environment provided by the mother can permanently program the health of the baby,» said Dr. Ponusammy Saravanan, senior author of the study. «We know that children born to mothers who under- or overfeed are at increased risk of health problems such as type 2 diabetes, and we also see that maternal B12 deficiency can affect fat metabolism and contribute to this risk. That's why we decided to investigate leptin, the fat cell hormone.’.
The next steps in the study will be to determine the details of how and why the increase in leptin is seen in babies born to mothers with low B12.
«Leptin can increase for two reasons,» said Dr. Adaikala Antonysunil, who also worked on the study. «Either low B12 leads to fat accumulation in the fetus and this leads to increased leptin, or low B12 causes chemical changes in the placental genes that produce leptin, producing more of the hormone. As B12 is involved in methylation reactions in the body that can affect whether genes are turned on and off, we suspect it may be the latter.».
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