Mother's Diet at Time of Conception Can Permanently Influence Baby's DNA

©. Catherine Thomas

We’ve all heard how important it is to eat well during pregnancy. Growing a baby is hard and risky work, and the better a mother eats, the healthier her child will be. But have you ever thought about the importance of maternal diet right at the time of conception? A study published last week in Nature Communications shows that the state of maternal nutrition during the periconceptual period (the period of time from before conception to early pregnancy) can alter fetal DNA.

The researchers analyzed the diets of 167 women in rural Gambia, a West African nation where nutritional intake varies greatly according to the season. Half of the women conceived during the dry season, which is known as “the harvest season,” and the other half conceived during the rainy season, or “the hungry season.” According to study author Robert Waterland, “During the rainy season, villagers have a lot more farming labour to do, and they gradually run out of food collected from the previous harvest.” The researchers also analyzed the DNA of six specific genes in the infants once they were between 2 and 8 months old.

Babies conceived during the rainy season, a time of year when women in Gambia eat more leafy greens that are high in folate, showed consistently higher rates of DNA methylation, which was contrary to the researchers’ initial hypothesis. When DNA methylation occurs, gene regions are tagged by chemical compounds called methyl groups which results in the gene not being expressed, but rather ‘silenced.’ Methylation requires the presence of key nutrients such as folate, vitamins B2, B6, and B12, choline, and methionine.

DNA methylation is an example of an ‘epigenetic’ modification, which is an external modification to DNA that turns genes on and off. These modifications don’t change the DNA sequence, but determine how cells read genes. For example, the colour of a mouse’s coat is determined by its mother’s diet, which is an external environmental, and therefore epigenetic, change that affects offspring.

The study’s senior author Dr. Branwen Heddig 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.”

What does this mean for pregnant women? It’s more important than ever to eat well and be healthy if you’re considering getting pregnant. The researchers hope this will lead to further study and the development of an optimal diet for mothers-to-be that would prevent defects in the methylation process and the eventual possibility of disease.