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Diet before pregnancy 'can affect baby's genes'

MOTHER'S diet can permanently alter the functioning of her son or daughter's genes even before the child is conceived, scientists have shown.

The evidence suggests that life-long health may be affected by what our mothers ate before getting pregnant, but precisely how remains an unanswered question. although experiments had already shown that this occurs in animals, it had never been demonstrated conclusively in humans before. one study in 2003 showed that a female mouse's diet can change her offspring's coat-colour by altering gene activity.

The new 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.

The study showed that a mother's diet before conception had a significant effect on the properties of her future children's genes.

While a child's genes are inherited directly from its parents, the way 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, the researchers found. 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 (BMI) of mothers.

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