We are what we eat

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![][1] The old adage that pregnant women eat for two might be more true than ever before in the light of recent research into diet and the control of gene expression. The link between the diet of pregnant women—and, to some extent, men—during pre‐conception and the health of the fetus has been viewed mostly in terms of major risk factors such as smoking or substance abuse. However, epidemiological and molecular research is revealing a more complex and subtle picture of how a pregnant woman's eating behaviour influences the expression of her own—and possibly her fetus's—genes, and thus the long‐term health of her children. “Type II diabetes, heart disease due to obesity, insulin resistance, and hypertension are the diseases most strongly associated with maternal diet during pregnancy,” said Karen Lillycrop, who specializes in perinatal nutrition at the University of Southampton in the UK. In addition, there is growing evidence that dietary effects, which can alter the expression and control of genes, might even have been a driving force for human evolution. A recent study revealed that the greatest divergence between the genomes of humans and chimpanzees is found among genes that control metabolism and are closely associated with diet (Somel et al , 2008). The mechanisms that allow the genome to interact with environmental factors, such as diet, are epigenetic changes—a concept first proposed by the British biologist Conrad Waddington (1905–1975) in 1942 to describe the interplay between genes and the environment in determining the phenotype of an organism. Further research since Waddington's time has shown that epigenetic changes not only take place during embryonic development, but also throughout the lifetime of an organism. The same mechanisms—notably DNA methylation and histone modification—have a role in the acquisition and maintenance of epigenetic changes induced by dietary or other environmental factors. In fact, they … [1]: /embed/graphic-1.gif