Babies whose mothers do not get enough essential B vitamins around the time of conception could be more at risk of Type 2 diabetes.
A study of female sheep showed that reducing their intake of B12 and folate (a form of vitamin B9) before pregnancy produced major physical effects in their offspring.
At only two years of age, the sheep showed signs of insulin resistance and were 25 per cent fatter than normal with higher blood pressure.
Scientists say there is a greater chance of these sheep developing Type 2 diabetes and becoming obese, and they are more at risk of heart disease.
The findings were published in the Proceedings of the National Academy of Sciences.
"This is an interesting new study but it is very early days yet, as it has only been undertaken with animals," said Caroline Butler, Care Advisor at Diabetes UK.
"Much more research is required before we can see if the results would be replicated in humans."
Vitamin B12 is essential for the synthesis of red blood cells and the maintenance of a healthy nervous system. It can be found in red meat, eggs and dairy products.