The new study, published in Epigenetics, suggests that while a high maternal intake of folate throughout gestation may be implicated in a later increased risk of childhood obesity, such risks can be mitigated if infants also follow a diet rich in folic acid.
Led by Professor G. Harvey Anderson from the University of Toronto, Canada, the research team noted that while women are advised to take high levels multivitamin (including folate) to reduce the risks of developmental problems such as neural tube defects in newborns - recent studies in rats have suggested that such high intakes may also have 'undesired consequences' including an increased risk of obesity in later life for the offspring.
"We have previously shown that high multivitamin diets fed during pregnancy to Wistar rats produce offspring with increased food intake, obesity and characteristics of the metabolic syndrome," explain the researchers.
However, Anderson and his team have now found that feeding infants a high folate diet similar to that of the maternal diet mitigates these effects.
"The obesogenic phenotype of offspring from dams fed the high-folate gestational diet can be corrected by feeding them a high-folate diet," said the authors - who suggested that such changes were "perhaps due to epigenetic changes involving methylation."
"We demonstrate for the first time that folate in either the gestational or post-weaning diets modifies hypothalamic feeding pathways in mature offspring," they added. "These results are novel in showing epigenetic plasticity of the hypothalamus that responds to folate consumption not only in utero but also in later life.
The team fed pregnant rats (dams) a standard diet that contained either the equivalent of a recommended vitamin intake or a high-folate diet - which contained the recommended intake plus ten times the recommendation for folate.
There were 10 dams per diet group, both of which had the same energy density (3.8 kcal/g).
The team then fed the male offspring of dams fed 10-fold folate diet during pregnancy were then weaned to either the recommended vitamin levels or a similar high-folate diet. They outcomes were then compared to the offspring of rats who had been fed the recommended vitamin intake during gestation and also during infancy.
They found that food intake and body weight were highest in offspring of high-folate dams who were then fed recommended levels, while "in contrast, the high-folate pup diet in offspring of high folate dams reduced food intake, body weight and glucose response to a glucose load, and improved glucose response to an insulin load."
"In conclusion, the obesogenic phenotype of offspring from dams fed the high-folate gestational diet can be corrected by feeding them a high-folate diet."
"Our work is novel in showing postweaning epigenetic plasticity of the hypothalamus and that in utero programming by vitamin gestational diets can be modified by vitamin content of the pup diet," commented Anderson and his colleagues.