A vitamin B12 deficiency during pregnancy may predispose children to metabolic problems such as type 2 diabetes according to new research from scientists in the UK.
The findings should be considered in terms of a review of current B12 requirement for pregnant women either through diet advice or supplements say the team of researchers from the University of Warwick.
Vitamin B12 is naturally found in animal products, including fish, meat, poultry, eggs and milk, meaning deficiency is more likely in those following a vegan diet, but people can take vitamin supplements if they are not getting enough from their diet.
Previous studies show that mothers with low B12 levels had a higher BMI and were more likely to give birth to babies with low birth weight as well as high cholesterol levels. These children also had higher insulin resistance in childhood, a risk factor for type 2 diabetes.
In this study the researchers from the university’s 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 produced by the body’s fat cells and its levels rise in response to eating food.
Whilst lean diets are associated with normal levels of leptin, obesity causes levels to rise and remain consistently higher than normal. This can eventually lead to leptin resistance, continued overeating, and an increased risk of insulin resistance, which leads to type 2 diabetes.
Scientists and doctors therefore see leptin as providing an effective ‘marker’ for body fat. The researchers found that babies born to mothers with B12 deficiency had higher than normal leptin levels. This suggests that maternal B12 deficiency can adversely program the leptin gene, changing the levels at which the hormone is produced whilst the foetus grows.
‘The nutritional environment provided by the mother can permanently program the baby’s health. We know that children born to under or over nourished mothers are at an increased risk of health problems such as type 2 diabetes and we also see that maternal B12 deficiency may affect fat metabolism and contribute to this risk. This is why we decided to investigate leptin, the fat cell hormone,’ said senior study author Dr Ponusammy Saravanan.
He explained that more work needs to be done. The next steps in the study, which has not yet been peer reviewed, is to determine the details of how and why the leptin increase is seen in babies born to mothers with low vitamin B12 levels.
‘The leptin can increase for two reasons. Either low B12 drives fat accumulation in the foetus, and this leads to increased leptin, or the low B12 actually causes chemical changes in the placental genes that produce leptin, making more of the hormone,’ said Dr Adaikala Antonysunil, who also worked on the study.
‘As B12 is involved in methylation reactions in the body which can affect whether genes are turned on and off, we suspect it may be the latter,’ he added.
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