Mum’s pre-pregnancy diet affects child’s genes, research reveals

A mother’s diet can permanently alter the functioning of her son or daughter’s genes — even before the child is conceived, a study shows.

The evidence suggests that lifelong health may be affected by what our mothers ate before getting pregnant, but precisely how remains unanswered.

Although experiments had already shown that this occurs in animals, it had never before been demonstrated conclusively in humans.

The research involved women in rural Gambia, where seasonal climate leads to big differences in diet between rainy and dry periods.

Scientists recruited 84 pregnant women who conceived at the peak of the rainy season, and about the same number who conceived at the peak of the dry season.

Nutrient levels were measured in blood samples taken from the women, and after they gave birth, the DNA of their babies at two to eight months old was analysed.

While a child’s genes are inherited directly from its parents, the way that they function is controlled through modifications to DNA.

One such “epigenetic” modification involves “silencing” genes by tagging specific regions of DNA with chemical compounds called methyl groups.

The addition of these compounds requires certain nutrients, including folate, vitamins B2, B6, and B12, choline and methionine.

Infants from rainy season conceptions had consistently higher rates of methyl groups present in all six genes studied. These were linked to various nutrient levels in the mother’s blood.

Strong associations were found with two compounds in particular, homocysteine and cysteine, as well as the body mass index of mothers.

But although the effects were seen at a biochemical level, their functional influence on genes remains unknown.

The study’s lead scientist, Dr Branwen Hennig, from the Medical Research Council’s Gambia unit and the London School of Hygiene and Tropical Medicine, said: “Our results represent the first demonstration in humans that a mother’s nutritional well-being at the time of conception can change how her child’s genes will be interpreted, with a lifelong impact.”

The findings appear in the latest edition of journal Nature Communications.

Co-author Andrew Prentice, professor of international nutrition at the London School of Hygiene and Tropical Medicine, said: “Our on- going research is yielding strong indications that the methylation machinery can be disrupted by nutrient deficiencies and that this can lead to disease.

“Our ultimate goal is to define an optimal diet for mothers-to-be that would prevent defects in the methylation process.”