Researchers based in the UK have found that the vitamin — principally found in meat and fish — can affect levels of a hormone called leptin, which triggers the “full” feeling after eating, and which can be linked to metabolic conditions such as diabetes.
Previous research found that mothers with low vitamin B12 levels had a higher BMI (Body Mass Index) and were at greater risk of giving birth to babies with low birth weights and high cholesterol levels. These children also showed greater insulin resistance during childhood, a risk factor for type 2 diabetes.
According to researchers at the University of Warwick, the metabolic changes linked to vitamin B12 deficiency could be caused by abnormal levels of leptin, a hormone that tells us when we are full after eating.
The researchers’ study showed that babies born to mothers deficient in B12 had higher than normal leptin levels. This suggests that a lack of B12 can adversely program the leptin gene, changing the levels at which the hormone is produced as the fetus grows.
Leptin is produced by the body’s fat cells and levels of the hormone rise in the body after eating. In cases of obesity, leptin levels rise and remain constantly higher than normal, which makes certain individuals feel hungry and overeat. This can cause leptin resistance, continued overeating and increased risk of insulin resistance, which leads to type 2 diabetes.
“The nutritional environment provided by the mother can permanently program the baby’s health,” said Dr Ponusammy Saravanan, senior author of the study. “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.”
The researchers propose two explanations for the difference in leptin level, with the second considered most likely. Either vitamin B12 deficiency could lead to the accumulation of fat in the fetus and increase levels of leptin, or it could cause chemical changes to placental genes that produce leptin, increasing levels of the hormone.
A regular dietary intake of meat and fish can ensure sufficient vitamin B12 levels during pregnancy. For non-meat eaters, vitamin B12 supplementation is particularly important (capsules or vial) to prevent anemia and maintain healthy brain function. Vitamin B12 is rare from plant sources and is found in very small quantities in dairy products and eggs.
Requirements for pregnant women are around 4 micrograms.