In rural Gambia, women’s diets change dramatically between the nutrient-rich rainy season and the leaner dry season. Most of us wouldn’t be surprised if the seasonal variation in nutrition influenced the health of babies conceived and carried during periods of relative boom or bust. But would you expect the effects to run as deep as the babies’ DNA?
That’s what a team of researchers from the MRC International Nutrition Group, the London School of Hygiene and Tropical Medicine, and the Baylor College of Medicine in Houston discovered by following a population of women and their offspring in rural Gambia. Emily Willingham, writing at The Scientist neatly outlines the study’s methodology:
The team enrolled 167 women in a prospective study. Of these, 84 women conceived during the peak rainy season and 83 became pregnant during the peak dry season. The investigators then evaluated concentrations of methylation-related chemicals such as homocysteine, folate, and B vitamins in maternal blood samples correlated with conception season and methylation patterns of infant blood and hair sample DNA. They found associations between maternal biomarkers and increased or decreased methylation in infant DNA, and that all of the maternal biomarkers together explained about 10 percent of the variation in these infant DNA methylation patterns.
Methylation is one of the mechanisms that controls gene expression. In other words, it influences which genes are turned “on” or “off” at any given time. It can have potentially huge developmental effects, but the authors of the study don’t yet know what the changes they observed actually do, in functional terms.
The importance of nutrition before and during pregnancy is well-established. Consider the B vitamin, folic acid. Web MD summarizes:
Women who are pregnant or might become pregnant take folic acid to prevent miscarriage and “neural tube defects,” birth defects such as spina bifida that occur when the fetus’s spine and back don’t close during development.
The new research implies that folic acid alone may not be the only nutrient of critical importance and that the ramifications of poor nutrition may be far more subtle than obvious — birth defect like spina bifida. According to Genetic Engineering & Biotechnology News:
Andrew Prentice, Ph.D., professor of international nutrition at the London School of Hygiene and Tropical Medicine, and head of the Nutrition Theme at the MRC Unit, The Gambia, said: “Our ongoing 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. Our research is pointing toward the need for a cocktail of nutrients, which could come from the diet or from supplements.”
This project is an extension of previous research in mice that showed diet could influence the methylation process in their offspring. It comes amid the release of a variety of research that points to the potential power of trans-generational epigenetics. A landmark paper recently demonstrated that epigenetic changes (read: changes in gene expression rather than the genetic code itself) could be passed down in mice; training mice to fear a specific smell had an influence on the nervous systems of their offspring.
The history of trans-generational epigenetics, notes Willingham, reaches all the way back to the Hungerwinter Study in the 1940s.The study followed mothers who had carried their children to term during the Dutch Famine of World War II. It found that children of the Hungerwinter suffered a variety of long-term consequences, including elevated risk of diabetes and cardiovascular disease.
As studies like the mice-smell study and this human baby nutrition study in Gambia continue to accumulate, it seems that methylation and other mechanisms of gene regulation may be behind these observations. It seems commonsense that nutrition would have a lasting impact on children, but we may only be coming to grips with the full depth of that impact now.
Kenrick Vezina is Gene-ius Editor for the Genetic Literacy Project and a freelance science writer, educator, and naturalist based in the Greater Boston Area.
- “Maternal nutrition at conception modulates DNA methylation of human metastable epialleles,” Nature Communications
- “Mother’s Diet Has Life-Long Effects on Child’s Gene Function,” Genetic Engineering & Biotechnology News
- “Epigenetic Effects of Mom’s Diet,” Emily Willingham | The Scientist
- “Can we inherit fear of a smell? The latest on transgenerational epigenetics,” Tabitha M. Powledge | Genetic Literacy Project
- “Pre-pregnancy diet ‘permanently influences baby’s DNA’,” Helen Briggs | BBC News
- “Mom’s Diet Right Before Pregnancy Can Alter Baby’s Genes,” Michaeleen Doucleff | NPR